LTC2261-14 LTC2260-14/LTC2259-14 14-Bit, 125/105/80Msps Ultralow Power 1.8V ADCs FEATURES DESCRIPTION n The LTC ®2261-14/LTC2260-14/LTC2259-14 are sampling 14-bit A/D converters designed for digitizing high frequency, wide dynamic range signals. They are perfect for demanding communications applications with AC performance that includes 73.4dB SNR and 85dB spurious free dynamic range (SFDR). Ultralow jitter of 0.17psRMS allows undersampling of IF frequencies with excellent noise performance. n n n n n n n n n n n n 73.4dB SNR 85dB SFDR Low Power: 127mW/106mW/89mW Single 1.8V Supply CMOS, DDR CMOS or DDR LVDS Outputs Selectable Input Ranges: 1VP-P to 2VP-P 800MHz Full-Power Bandwidth S/H Optional Data Output Randomizer Optional Clock Duty Cycle Stabilizer Shutdown and Nap Modes Serial SPI Port for Configuration Pin Compatible 14-Bit and 12-Bit Versions 40-Pin (6mm × 6mm) QFN Package DC specs include ±1LSB INL (typical), ±0.3LSB DNL (typical) and no missing codes over temperature. The transition noise is a low 1.2LSBRMS. The digital outputs can be either full rate CMOS, double data rate CMOS, or double data rate LVDS. A separate output power supply allows the CMOS output swing to range from 1.2V to 1.8V. APPLICATIONS n n n n n n The ENC+ and ENC– inputs may be driven differentially or single ended with a sine wave, PECL, LVDS, TTL or CMOS inputs. An optional clock duty cycle stabilizer allows high performance at full speed for a wide range of clock duty cycles. Communications Cellular Base Stations Software Defined Radios Portable Medical Imaging Multi-Channel Data Acquisition Nondestructive Testing L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. TYPICAL APPLICATION 2-Tone FFT, fIN = 70MHz and 75MHz 1.8V 0 1.2V TO 1.8V VDD –10 –20 OVDD ANALOG INPUT INPUT S/H – 14-BIT PIPELINED ADC CORE CORRECTION LOGIC D13 CMOS • OR • LVDS • D0 OUTPUT DRIVERS OGND CLOCK/DUTY CYCLE CONTROL AMPLITUDE (dBFS) –30 + –40 –50 –60 –70 –80 –90 –100 –110 –120 0 125MHz CLOCK GND 226114 TA01a 10 20 30 40 FREQUENCY (MHz) 50 60 226114 TA01b 226114f 1 LTC2261-14 LTC2260-14/LTC2259-14 ABSOLUTE MAXIMUM RATINGS (Notes 1, 2) Supply Voltages (VDD, OVDD) ....................... –0.3V to 2V Analog Input Voltage (AIN+, AIN–, PAR/SER, SENSE) (Note 3) ...........–0.3V to (VDD + 0.2V) Digital Input Voltage (ENC+, ENC–, CS, SDI, SCK) (Note 4) .................................... –0.3V to 3.9V SDO (Note 4) ............................................ –0.3V to 3.9V Digital Output Voltage ................ –0.3V to (OVDD + 0.3V) Operating Temperature Range: LTC2261C, LTC2260C, LTC2259C............. 0°C to 70°C LTC2261I, LTC2260I, LTC2259I ............ –40°C to 85°C Storage Temperature Range................... –65°C to 150°C PIN CONFIGURATIONS 40 39 38 37 36 35 34 33 32 31 DNC D10_11 DNC D12_13 DNC OF VCM VREF VDD D10 D11 D12 D13 DNC OF VCM VREF SENSE VDD SENSE DOUBLE DATA RATE CMOS OUTPUT MODE TOP VIEW FULL-RATE CMOS OUTPUT MODE TOP VIEW 40 39 38 37 36 35 34 33 32 31 AIN+ 1 30 D9 AIN+ 1 30 D8_9 AIN– 2 29 D8 AIN– 2 29 DNC GND 3 28 CLKOUT+ GND 3 28 CLKOUT+ REFH 4 27 CLKOUT– REFH 4 27 CLKOUT– REFH 5 26 OVDD REFH 5 25 OGND REFL 6 REFL 7 24 D7 REFL 7 PAR/SER 8 23 D6 PAR/SER 8 VDD 9 22 D5 VDD 9 VDD 10 21 D4 VDD 10 25 OGND 24 D6_7 23 DNC 22 D4_5 21 DNC D2_3 DNC D0_1 DNC SDO SDI SCK ENC+ UJ PACKAGE 40-LEAD (6mm s 6mm) PLASTIC QFN CS 11 12 13 14 15 16 17 18 19 20 D3 D2 D1 D0 SDO SDI SCK CS ENC+ ENC– 11 12 13 14 15 16 17 18 19 20 26 OVDD 41 ENC– 41 REFL 6 UJ PACKAGE 40-LEAD (6mm s 6mm) PLASTIC QFN TJMAX = 150°C, θJA = 32°C/W EXPOSED PAD (PIN 41) IS GND, MUST BE SOLDERED TO PCB TJMAX = 150°C, θJA = 32°C/W EXPOSED PAD (PIN 41) IS GND, MUST BE SOLDERED TO PCB D10_11– D10_11+ D12_13– D12_13+ OF– OF+ VCM VREF SENSE VDD DOUBLE DATA RATE LVDS OUTPUT MODE TOP VIEW 40 39 38 37 36 35 34 33 32 31 AIN+ 1 30 D8_9+ AIN– 2 29 D8_9– GND 3 28 CLKOUT+ REFH 4 27 CLKOUT– REFH 5 26 OVDD 41 REFL 6 25 OGND REFL 7 24 D6_7+ PAR/SER 8 23 D6_7– VDD 9 22 D4_5+ VDD 10 21 D4_5– D2_3+ D2_3– D0_1+ D0_1– SDO SDI SCK CS ENC– ENC+ 11 12 13 14 15 16 17 18 19 20 UJ PACKAGE 40-LEAD (6mm s 6mm) PLASTIC QFN TJMAX = 150°C, θJA = 32°C/W EXPOSED PAD (PIN 41) IS GND, MUST BE SOLDERED TO PCB 226114f 2 LTC2261-14 LTC2260-14/LTC2259-14 ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC2261CUJ-14#PBF LTC2261CUJ-14#TRPBF LTC2261UJ-14 40-Lead (6mm × 6mm) Plastic QFN 0°C to 70°C LTC2261IUJ-14#PBF LTC2261IUJ-14#TRPBF LTC2261UJ-14 40-Lead (6mm × 6mm) Plastic QFN –40°C to 85°C LTC2260CUJ-14#PBF LTC2260CUJ-14#TRPBF LTC2260UJ-14 40-Lead (6mm × 6mm) Plastic QFN 0°C to 70°C LTC2260IUJ-14#PBF LTC2260IUJ-14#TRPBF LTC2260UJ-14 40-Lead (6mm × 6mm) Plastic QFN –40°C to 85°C LTC2259CUJ-14#PBF LTC2259CUJ-14#TRPBF LTC2259UJ-14 40-Lead (6mm × 6mm) Plastic QFN 0°C to 70°C LTC2259IUJ-14#PBF LTC2259IUJ-14#TRPBF LTC2259UJ-14 40-Lead (6mm × 6mm) Plastic QFN –40°C to 85°C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ CONVERTER CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 5) LTC2261-14 PARAMETER CONDITIONS MIN l Resolution (No Missing Codes) TYP LTC2260-14 MAX 14 MIN TYP LTC2259-14 MAX 14 MIN TYP MAX 14 UNITS Bits Integral Linearity Error Differential Analog Input (Note 6) l –3.75 ±1 3.75 –3.75 ±1 3.75 –3.5 ±1 3.5 LSB Differential Linearity Error Differential Analog Input l –0.9 ±0.3 0.9 –0.9 ±0.3 0.9 –0.9 ±0.3 0.9 LSB Offset Error (Note 7) l –9 ±1.5 9 –9 ±1.5 9 –9 ±1.5 9 mV Gain Error Internal Reference External Reference l –1.5 ±1.5 ±0.4 1.5 –1.5 ±1.5 ±0.4 1.5 –1.5 ±1.5 ±0.4 1.5 %FS %FS Offset Drift ±20 ±20 ±20 μV/°C Full-Scale Drift Internal Reference External Reference ±30 ±10 ±30 ±10 ±30 ±10 ppm/°C ppm/°C Transition Noise External Reference 1.2 1.2 1.2 LSBRMS 226114f 3 LTC2261-14 LTC2260-14/LTC2259-14 ANALOG INPUT The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 5) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS VIN Analog Input Range (AIN+ – AIN–) 1.7V < VDD < 1.9V l Differential Analog Input (Note 8) l VCM – 100mV VCM VCM + 100mV V l 0.625 1.250 1.300 V 1 to 2 VP-P VIN(CM) Analog Input Common Mode (AIN+ + AIN–)/2 VSENSE External Voltage Reference Applied to SENSE External Reference Mode IINCM Analog Input Common Mode Current Per Pin, 125Msps Per Pin, 105Msps Per Pin, 80Msps IIN1 Analog Input Leakage Current 0 < AIN+, AIN– < VDD, No Encode l –1 1 μA IIN2 PAR/SER Input Leakage Current 0 < PAR/SER < VDD l –3 3 μA IIN3 SENSE Input Leakage Current 0.625 < SENSE < 1.3V l –6 6 μA tAP Sample-and-Hold Acquisition Delay Time 0 tJITTER Sample-and-Hold Acquisition Delay Jitter 0.17 CMRR Analog Input Common Mode Rejection Ratio BW-3B Full-Power Bandwidth 155 130 100 Figure 6 Test Circuit μA μA μA ns psRMS 80 dB 800 MHz DYNAMIC ACCURACY The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. AIN = –1dBFS. (Note 5) LTC2261-14 SYMBOL PARAMETER CONDITIONS SNR Signal-to-Noise Ratio 5MHz Input 70MHz Input 140MHz Input SFDR S/(N+D) MIN TYP l 71.3 Spurious Free Dynamic Range 5MHz Input 2nd or 3rd Harmonic 70MHz Input 140MHz Input l Spurious Free Dynamic Range 5MHz Input 4th Harmonic or Higher 70MHz Input 140MHz Input Signal-to-Noise Plus Distortion Ratio 5MHz Input 70MHz Input 140MHz Input MAX LTC2260-14 MIN TYP 73.4 73.2 72.7 71.3 76 88 85 82 l 85 l 70.2 MAX LTC2259-14 MIN TYP MAX UNITS 73.4 73.2 72.7 70.9 73.1 72.9 72.4 dB dB dB 76 88 85 82 79 88 85 82 dB dB dB 90 90 90 83 90 90 90 85 90 90 90 dB dB dB 73 72.6 72 70.2 73 72.6 72 70.4 72.9 72.6 72 dB dB dB INTERNAL REFERENCE CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 5) PARAMETER CONDITIONS VCM Output Voltage IOUT = 0 MIN TYP MAX 0.5 • VDD – 25mV 0.5 • VDD 0.5 • VDD + 25mV VCM Output Temperature Drift ±25 VCM Output Resistance –600μA < IOUT < 1mA VREF Output Voltage IOUT = 0 VREF Output Temperature Drift 1.250 ±25 VREF Output Resistance –400μA < IOUT < 1mA VREF Line Regulation 1.7V < VDD < 1.9V 7 0.6 V ppm/°C 4 1.225 UNITS Ω 1.275 V ppm/°C Ω mV/V 226114f 4 LTC2261-14 LTC2260-14/LTC2259-14 DIGITAL INPUTS AND OUTPUTS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 5) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS ENCODE INPUTS (ENC+, ENC– ) Differential Encode Mode (ENC– Not Tied to GND) VID Differential Input Voltage (Note 8) l 0.2 VICM Common Mode Input Voltage Internally Set Externally Set (Note 8) l 1.1 1.6 V V l 0.2 3.6 V V 1.2 VIN Input Voltage Range ENC+, ENC– to GND RIN Input Resistance (See Figure 10) 10 kΩ CIN Input Capacitance (Note 8) 3.5 pF Single-Ended Encode Mode (ENC– Tied to GND) VIH High Level Input Voltage VDD = 1.8V l VIL Low Level Input Voltage VDD = 1.8V l VIN Input Voltage Range ENC+ to GND l RIN Input Resistance (See Figure 11) 30 kΩ CIN Input Capacitance (Note 8) 3.5 pF 1.2 V 0.6 0 3.6 V V DIGITAL INPUTS (CS, SDI, SCK) VIH High Level Input Voltage VDD = 1.8V l VIL Low Level Input Voltage VDD = 1.8V l l IIN Input Current VIN = 0V to 3.6V CIN Input Capacitance (Note 8) 1.3 V –10 0.6 V 10 μA 3 pF 200 Ω SDO OUTPUT (Open-Drain Output. Requires 2k Pull-Up Resistor if SDO is Used) ROL Logic Low Output Resistance to GND VDD = 1.8V, SDO = 0V IOH Logic High Output Leakage Current SDO = 0V to 3.6V COUT Output Capacitance (Note 8) l –10 10 μA 4 pF 1.790 V DIGITAL DATA OUTPUTS (CMOS MODES: FULL DATA RATE AND DOUBLE DATA RATE) OVDD = 1.8V VOH High Level Output Voltage IO = –500μA l VOL Low Level Output Voltage IO = 500μA l 1.750 0.010 0.050 V OVDD = 1.5V VOH High Level Output Voltage IO = –500μA 1.488 V VOL Low Level Output Voltage IO = 500μA 0.010 V OVDD = 1.2V VOH High Level Output Voltage IO = –500μA 1.185 V VOL Low Level Output Voltage IO = 500μA 0.010 V DIGITAL DATA OUTPUTS (LVDS MODE) VOD Differential Output Voltage 100Ω Differential Load, 3.5mA Mode 100Ω Differential Load, 1.75mA Mode l 247 350 175 454 VOS Common Mode Output Voltage 100Ω Differential Load, 3.5mA Mode 100Ω Differential Load, 1.75mA Mode l 1.125 1.250 1.250 1.375 RTERM On-Chip Termination Resistance Termination Enabled, OVDD = 1.8V 100 mV mV V V Ω 226114f 5 LTC2261-14 LTC2260-14/LTC2259-14 POWER REQUIREMENTS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 9) LTC2261-14 SYMBOL PARAMETER CONDITIONS MIN TYP 1.8 LTC2260-14 MAX MIN TYP 1.9 1.7 1.8 1.9 1.1 LTC2259-14 MAX MIN TYP 1.9 1.7 1.8 1.9 1.1 MAX UNITS CMOS Output Modes: Full Data Rate and Double Data Rate VDD Analog Supply Voltage (Note 10) l 1.7 OVDD Output Supply Voltage (Note 10) l 1.1 IVDD Analog Supply Current DC Input Sine Wave Input l IOVDD Digital Supply Current Sine Wave Input, OVDD=1.2V 3.9 PDISS Power Dissipation l DC Input Sine Wave Input, OVDD=1.2V 127 134 70.5 71.8 83.2 58.6 59.8 69.1 49.2 50.2 3.3 150 1.9 V 1.9 V 58.1 mA mA 2.5 106 112 125 mA 89 93 105 mW mW LVDS Output Mode VDD Analog Supply Voltage (Note 10) l 1.7 OVDD Output Supply Voltage (Note 10) l 1.7 1.8 1.9 1.7 1.9 1.7 1.8 1.9 1.7 1.9 1.7 1.8 1.9 V 1.9 V IVDD Analog Supply Current Sine Wave Input l 75.4 89 63.4 74.8 53.8 63.5 mA IOVDD Digital Supply Current (0VDD = 1.8V) Sine Input, 1.75mA Mode Sine Input, 3.5mA Mode l l 20.7 40.5 26 47.8 20.7 40.5 26 47.8 20.7 40.5 26 47.8 mA mA PDISS Power Dissipation Sine Input, 1.75mA Mode Sine Input, 3.5mA Mode l l 173 209 207 246 151 187 182 221 134 170 161 201 mW mW All Output Modes PSLEEP Sleep Mode Power 0.5 0.5 0.5 mW PNAP Nap Mode Power 9 9 9 mW PDIFFCLK Power Increase with Differential Encode Mode Enabled (No increase for Nap or Sleep Modes) 10 10 10 mW TIMING CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 5) LTC2261-14 MIN TYP LTC2260-14 SYMBOL PARAMETER CONDITIONS MAX MIN fS Sampling Frequency (Note 10) l 1 125 1 tL ENC Low Time (Note 8) Duty Cycle Stabilizer Off Duty Cycle Stabilizer On l l 3.8 2.0 4 4 500 500 tH ENC High Time (Note 8) Duty Cycle Stabilizer Off Duty Cycle Stabilizer On l l 3.8 2.0 4 4 500 500 tAP Sample-and-Hold Acquisition Delay Time SYMBOL PARAMETER LTC2259-14 TYP MAX 105 1 4.52 2.00 4.76 4.76 500 500 4.52 2.00 4.76 4.76 500 500 0 MIN TYP MAX 80 MHz 5.93 2.00 6.25 6.25 500 500 ns ns 5.93 2.00 6.25 6.25 500 500 ns ns 0 CONDITIONS 0 MIN TYP UNITS ns MAX UNITS Digital Data Outputs (CMOS Modes: Full Data Rate and Double Data Rate) tD ENC to Data Delay CL = 5pF (Note 8) l 1.1 1.7 3.1 ns tC ENC to CLKOUT Delay CL = 5pF (Note 8) l 1 1.4 2.6 ns tSKEW DATA to CLKOUT Skew tD – tC (Note 8) l 0 0.3 0.6 ns Pipeline Latency Full Data Rate Mode Double Data Rate Mode 5.0 5.5 Cycles Cycles 226114f 6 LTC2261-14 LTC2260-14/LTC2259-14 TIMING CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 5) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Digital Data Outputs (LVDS Mode) tD ENC to Data Delay CL = 5pF (Note 8) l 1.1 1.8 3.2 ns tC ENC to CLKOUT Delay CL = 5pF (Note 8) l 1 1.5 2.7 ns tSKEW DATA to CLKOUT Skew tD – tC (Note 8) l 0 0.3 0.6 ns Pipeline Latency 5.5 Cycles SPI Port Timing (Note 8) l l 40 250 ns ns CS to SCK Setup Time l 5 ns tH SCK to CS Setup Time l 5 ns tDS SDI Setup Time l 5 ns tDH SDI Hold Time l 5 tDO SCK Falling to SDO Valid tSCK SCK Period tS Write Mode Readback Mode, CSDO = 20pF, RPULLUP = 2k Readback Mode, CSDO = 20pF, RPULLUP = 2k Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: All voltage values are with respect to GND with GND and OGND shorted (unless otherwise noted). Note 3: When these pin voltages are taken below GND or above VDD, they will be clamped by internal diodes. This product can handle input currents of greater than 100mA below GND or above VDD without latchup. Note 4: When these pin voltages are taken below GND they will be clamped by internal diodes. When these pin voltages are taken above VDD they will not be clamped by internal diodes. This product can handle input currents of greater than 100mA below GND without latchup. Note 5: VDD = OVDD = 1.8V, fSAMPLE = 125MHz (LTC2261), 105MHz (LTC2260), or 80MHz (LTC2259), LVDS outputs with internal ns l 125 ns termination disabled, differential ENC+/ENC– = 2VP-P sine wave, input range = 2VP-P with differential drive, unless otherwise noted. Note 6: Integral nonlinearity is defined as the deviation of a code from a best fit straight line to the transfer curve. The deviation is measured from the center of the quantization band. Note 7: Offset error is the offset voltage measured from –0.5 LSB when the output code flickers between 00 0000 0000 0000 and 11 1111 1111 1111 in 2’s complement output mode. Note 8: Guaranteed by design, not subject to test. Note 9: VDD = 1.8V, fSAMPLE = 125MHz (LTC2261), 105MHz (LTC2260), or 80MHz (LTC2259), ENC+ = single-ended 1.8V square wave, ENC– = 0V, input range = 2VP-P with differential drive, 5pF load on each digital output unless otherwise noted. Note 10: Recommended operating conditions. TIMING DIAGRAMS Full-Rate CMOS Output Mode Timing All Outputs are Single-Ended and Have CMOS Levels tAP ANALOG INPUT N+4 N+2 N N+3 tH N+1 tL ENC– ENC+ tD N–5 D0-D13, OF CLKOUT + CLKOUT – N–4 N–3 N–2 N–1 tC 226114 TD01 226114f 7 LTC2261-14 LTC2260-14/LTC2259-14 TIMING DIAGRAMS Double Data Rate CMOS Output Mode Timing All Outputs are Single-Ended and Have CMOS Levels tAP ANALOG INPUT N+4 N+2 N N+3 tH N+1 tL ENC– ENC+ tD D0_1 tD D0N-5 D1N-5 D0N-4 D1N-4 D0N-3 D1N-3 D0N-2 D1N-2 D12N-5 D13N-5 D12N-4 D13N-4 D12N-3 D13N-3 D12N-2 D13N-2 •• • D12_13 OFN-5 OF OFN-4 OFN-2 tC tC CLKOUT+ OFN-3 CLKOUT – 226114 TD02 Double Data Rate LVDS Output Mode Timing All Outputs are Differential and Have LVDS Levels tAP ANALOG INPUT N+4 N+2 N N+3 tH N+1 tL ENC– ENC+ D0_1+ D0_1– tD tD D0N-5 D1N-5 D0N-4 D1N-4 D0N-3 D1N-3 D0N-2 D1N-2 D12N-5 D13N-5 D12N-4 D13N-4 D12N-3 D13N-3 D12N-2 D13N-2 •• • D12_13+ D12_13– OF+ OF– CLKOUT+ CLKOUT – OFN-5 tC OFN-4 OFN-3 OFN-3 tC 226114 TD03 226114f 8 LTC2261-14 LTC2260-14/LTC2259-14 TIMING DIAGRAMS SPI Port Timing (Readback Mode) tDS tS tDH tSCK tH CS SCK tDO SDI A6 R/W A5 A4 A3 A2 A1 A0 SDO XX D7 HIGH IMPEDANCE XX XX D6 D5 XX XX D4 XX D3 D2 XX XX D1 D0 SPI Port Timing (Write Mode) CS SCK SDI A6 R/W A5 A4 A3 A2 A1 A0 D7 D6 D5 D4 D3 D2 D1 D0 SDO 226114 TD04 HIGH IMPEDANCE TYPICAL PERFORMANCE CHARACTERISTICS LTC2261-14: Integral Non-Linearity (INL) LTC2261-14: Differential Non-Linearity (DNL) 2.0 1.0 0 1.5 0.8 –10 –20 0.6 0.5 0 –0.5 –1.0 –30 0.4 AMPLITUDE (dBFS) DNL ERROR (LSB) 1.0 INL ERROR (LSB) LTC2261-14: 8k Point FFT, fIN = 5MHz –1dBFS, 125Msps 0.2 0 –0.2 –0.4 –2.0 –0.8 0 4096 8192 12288 OUTPUT CODE 16384 226114 G01 –1.0 –60 –70 –80 –90 –100 –0.6 –1.5 –40 –50 –110 –120 0 4096 8192 12288 OUTPUT CODE 16384 226114 G02 0 10 20 30 40 FREQUENCY (MHz) 50 60 226114 G03 226114f 9 LTC2261-14 LTC2260-14/LTC2259-14 TYPICAL PERFORMANCE CHARACTERISTICS LTC2261-14: 8k Point FFT, fIN = 70MHz –1dBFS, 125Msps LTC2261-14: 8k Point FFT, fIN = 140MHz –1dBFS, 125Msps 0 0 –10 –10 –20 –20 –20 –30 –30 –30 –40 –50 –60 –70 –80 AMPLITUDE (dBFS) 0 –10 AMPLITUDE (dBFS) AMPLITUDE (dBFS) LTC2261-14: 8k Point FFT, fIN = 30MHz –1dBFS, 125Msps –40 –50 –60 –70 –80 –70 –80 –90 –100 –90 –100 –110 –120 –110 –120 –110 –120 10 20 30 40 FREQUENCY (MHz) 50 0 60 10 20 30 40 FREQUENCY (MHz) 50 0 60 20 30 40 FREQUENCY (MHz) 10 50 226114 G05 226114 G04 LTC2261-14: 8k Point 2-Tone FFT, fIN = 70MHz, 75MHz, –1dBFS, 125Msps 226114 G06 LTC2261-14: Shorted Input Histogram 0 6000 –20 60 LTC2261-14: SNR vs Input Frequency, –1dB, 2V Range, 125Msps 74 –10 73 5000 72 –30 –40 –50 SNR (dBFS) 4000 COUNT 3000 –60 –70 –80 2000 –90 –100 1000 71 70 69 68 –110 –120 0 10 20 30 40 FREQUENCY (MHz) 50 67 0 8178 60 8180 8182 8184 OUTPUT CODE 226114 G07 66 8186 95 100 90 80 75 SFDR (dBc AND dBFS) 80 70 60 LVDS OUTPUTS 70 dBc 50 40 65 CMOS OUTPUTS 60 30 20 70 350 dBFS 90 75 100 150 200 250 300 INPUT FREQUENCY (MHz) LTC2261-14: IVDD vs Sample Rate, 5MHz Sine Wave Input, –1dB 110 80 50 226114 G09 LTC2261-14: SFDR vs Input Level, fIN = 70MHz, 2V Range, 125Msps 85 0 226114 G08 LTC2261-14: SFDR vs Input Frequency, –1dB, 2V Range, 125Msps IVDD (mA) AMPLITUDE (dBFS) –60 –90 –100 0 SFDR (dBFS) –40 –50 55 10 65 0 50 100 150 200 250 300 INPUT FREQUENCY (MHz) 350 226114 G10 0 –80 –70 –60 –50 –40 –30 –20 –10 INPUT LEVEL (dBFS) 50 0 226114 G12 0 25 50 75 100 SAMPLE RATE (Msps) 125 226114 G13 226114f 10 LTC2261-14 LTC2260-14/LTC2259-14 TYPICAL PERFORMANCE CHARACTERISTICS LTC2261-14: IOVDD vs Sample Rate, 5MHz Sine Wave Input, –1dB, 5pF on Each Data Output LTC2261-14: 128k Point Averaged FFT, fIN = 70MHz, –65dBFS, 125Msps, RAND OFF, ABP OFF LTC2261-14: SNR vs SENSE, fIN = 5MHz, –1dB 45 0 –10 –20 –30 –40 –50 –60 –70 –80 –90 –100 –110 –120 –130 74 3.5mA LVDS 40 73 35 AMPLITUDE (dBFS) 72 25 71 SNR (dBFS) 1.75mA LVDS 20 70 69 15 68 10 1.8V CMOS 5 0 67 1.2V CMOS 0 25 50 75 100 SAMPLE RATE (Msps) 66 125 0.6 0.7 0.8 0.9 1 1.1 SENSE PIN (V) 1.2 226114 G14 2.0 LVDS 1.5 CMOS 1.0 72 DDR CMOS SNR (dBFS) AMPLITUDE (dBFS) 60 LTC2260-14: Integral Non-Linearity (INL) 74 70 0.5 0 –0.5 –1.0 68 –1.5 66 0 10 20 30 40 50 FREQUENCY (MHz) 60 0 25 50 75 100 SAMPLE RATE (Msps) –2.0 125 0 –10 –10 –20 –20 –30 –30 AMPLITUDE (dBFS) 0.6 –0.2 –0.4 –0.6 –0.8 0 4096 8192 12288 OUTPUT CODE 16384 226114 G22 AMPLITUDE (dBFS) 0 0.8 0 8192 12288 OUTPUT CODE –40 –50 –60 –70 –80 –40 –50 –60 –70 –80 –90 –100 –90 –100 –110 –120 –110 –120 0 10 20 30 40 FREQUENCY (MHz) 50 226114 G23 16384 LTC2260-14: 8k Point FFT, fIN = 30MHz –1dBFS, 105Msps 1.0 0.2 4096 226114 G21 LTC2260-14: 8k Point FFT, fIN = 5MHz –1dBFS, 105Msps LTC2260-14: Differential Non-Linearity (DNL) 0.4 0 226114 G18 226114 G17 DNL ERROR (LSB) 20 30 40 50 FREQUENCY (MHz) 10 226114 G16 LTC2261-14: SNR vs Sample Rate and Digital Output Mode, 30MHz Sine Wave Input, –1dB 0 –10 –20 –30 –40 –1.0 0 226114 G15 LTC2261-14: 128k Point Averaged FFT, fIN = 70MHz, –65dBFS, 125Msps, RAND ON, ABP ON –50 –60 –70 –80 –90 –100 –110 –120 –130 1.3 INL ERROR (LSB) IOVDD (mA) 30 0 10 20 30 40 FREQUENCY (MHz) 50 226114 G24 226114f 11 LTC2261-14 LTC2260-14/LTC2259-14 TYPICAL PERFORMANCE CHARACTERISTICS LTC2260-14: 8k Point 2-Tone FFT, fIN = 70MHz, 75MHz, –1dBFS, 105Msps LTC2260-14: 8k Point FFT, fIN = 140MHz –1dBFS, 105Msps 0 0 –10 –10 –20 –20 –20 –30 –30 –30 –40 –50 –60 –70 –80 AMPLITUDE (dBFS) 0 –10 AMPLITUDE (dBFS) AMPLITUDE (dBFS) LTC2260-14: 8k Point FFT, fIN = 70MHz –1dBFS, 105Msps –40 –50 –60 –70 –80 –40 –50 –60 –70 –80 –90 –100 –90 –100 –90 –100 –110 –120 –110 –120 –110 –120 0 10 20 30 40 FREQUENCY (MHz) 50 0 10 20 30 40 FREQUENCY (MHz) 226114 G25 0 50 20 30 40 FREQUENCY (MHz) 10 226114 G27 226114 G26 LTC2260-14: SNR vs Input Frequency, –1dB, 2V Range, 105Msps LTC2260-14: Shorted Input Histogram LTC2260-14: SFDR vs Input Frequency, –1dB, 2V Range, 105Msps 95 74 6000 73 5000 50 90 72 3000 2000 71 SFDR (dBFS) COUNT SNR (dBFS) 4000 70 69 85 80 75 68 1000 70 67 8197 8199 8201 OUTPUT CODE 66 8203 65 0 50 100 150 200 250 300 INPUT FREQUENCY (MHz) LTC2260-14: SFDR vs Input Level, fIN = 70MHz, 2V Range, 105Msps 65 350 45 3.5mA LVDS 40 90 60 35 LVDS OUTPUTS 30 dBc IVDD (mA) SFDR (dBc AND dBFS) 100 150 200 250 300 INPUT FREQUENCY (MHz) 226114 G30 dBFS 80 60 50 LTC2260-14: IOVDD vs Sample Rate, 5MHz Sine Wave Input, –1dB, 5pF on Each Data Output LTC2260-14: IVDD vs Sample Rate, 5MHz Sine Wave Input, –1dB 110 70 0 226114 G29 226114 G28 100 350 50 40 IOVDD (mA) 0 8195 55 CMOS OUTPUTS 50 25 1.75mA LVDS 20 15 30 10 45 20 1.8V CMOS 5 10 0 –80 –70 –60 –50 –40 –30 –20 –10 INPUT LEVEL (dBFS) 0 226114 G32 40 0 25 50 75 SAMPLE RATE (Msps) 100 226114 G33 0 0 25 1.2V CMOS 50 75 100 SAMPLE RATE (Msps) 226114 G34 226114f 12 LTC2261-14 LTC2260-14/LTC2259-14 TYPICAL PERFORMANCE CHARACTERISTICS LTC2260-14: SNR vs SENSE, fIN = 5MHz, –1dB LTC2259-14: Integral Non-Linearity (INL) 2.0 1.0 73 1.5 0.8 72 1.0 SNR (dBFS) 70 69 0.6 0.5 0 –0.5 68 –1.0 67 –1.5 66 –2.0 0.4 DNL ERROR (LSB) INL ERROR (LSB) 74 71 0.2 0 –0.2 –0.4 –0.6 0.6 0.7 0.8 0.9 1 1.1 SENSE PIN (V) 1.2 1.3 –0.8 –1.0 0 4096 8192 12288 OUTPUT CODE 16384 0 –10 –20 –20 –20 –30 –30 –30 –70 –80 AMPLITUDE (dBFS) 0 –10 AMPLITUDE (dBFS) 0 –60 –40 –50 –60 –70 –80 –40 –60 –70 –80 –90 –100 –90 –100 –110 –120 –110 –120 –110 –120 10 20 30 FREQUENCY (MHz) 0 40 10 20 30 FREQUENCY (MHz) 0 –10 –20 –20 –30 –30 –60 –70 –80 6000 5000 –40 4000 –50 –60 3000 –70 2000 –90 –100 1000 –110 –120 –110 –120 20 30 FREQUENCY (MHz) 40 226114 G46 40 LTC2259-14: Shorted Input Histogram –80 10 20 30 FREQUENCY (MHz) 226114 G45 –90 –100 0 10 COUNT AMPLITUDE (dBFS) AMPLITUDE (dBFS) 0 –10 –40 0 LTC2259-14: 8k Point 2-Tone FFT, fIN = 70MHz, 75MHz, –1dBFS, 80Msps LTC2259-14: 8k Point FFT, fIN = 140MHz –1dBFS, 80Msps –50 40 226114 G44 226114 G43 16384 –50 –90 –100 0 8192 12288 OUTPUT CODE LTC2259-14: 8k Point FFT, fIN = 70MHz –1dBFS, 80Msps –10 –50 4096 226114 G42 LTC2259-14: 8k Point FFT, fIN = 30MHz –1dBFS, 80Msps LTC2259-14: 8k Point FFT, fIN = 5MHz –1dBFS, 80Msps –40 0 226114 G41 226114 G35 AMPLITUDE (dBFS) LTC2259-14: Differential Non-Linearity (DNL) 0 10 20 30 FREQUENCY (MHz) 40 226114 G47 0 8184 8186 8188 8190 OUTPUT CODE 8192 226114 G48 226114f 13 LTC2261-14 LTC2260-14/LTC2259-14 TYPICAL PERFORMANCE CHARACTERISTICS LTC2259-14: SNR vs Input Frequency, –1dB, 2V Range, 80Msps LTC2259-14: SFDR vs Input Frequency, –1dB, 2V Range, 80Msps LTC2259-14: SFDR vs Input Level, fIN = 70MHz, 2V Range, 80Msps 95 74 110 100 73 90 70 69 SFDR (dBc AND dBFS) SFDR (dBFS) SNR (dBFS) 72 71 85 80 75 68 80 70 dBc 60 50 40 30 20 70 67 66 dBFS 90 10 65 0 50 100 150 200 250 300 INPUT FREQUENCY (MHz) 350 0 50 100 150 200 250 300 INPUT FREQUENCY (MHz) 0 –80 –70 –60 –50 –40 –30 –20 –10 INPUT LEVEL (dBFS) 350 226114 G50 226114 G49 226114 G52 LTC2259-14: IOVDD vs Sample Rate, 5MHz Sine Wave Input, –1dB, 5pF on Each Data Output LTC2259-14: IVDD vs Sample Rate, 5MHz Sine Wave Input, –1dB 55 0 LTC2259-14: SNR vs SENSE, fIN = 5MHz, –1dB 45 74 3.5mA LVDS 40 35 LVDS OUTPUTS 50 73 72 45 CMOS OUTPUTS 25 SNR (dBFS) IOVDD (mA) IVDD (mA) 30 1.75mA LVDS 20 15 40 0 20 40 60 SAMPLE RATE (Msps) 80 0 70 69 68 10 1.2V CMOS 1.8V CMOS 5 35 71 0 20 40 60 SAMPLE RATE (Msps) 226114 G53 67 80 226114 G54 66 0.6 0.7 0.8 0.9 1 1.1 SENSE PIN (V) 1.2 1.3 226114 G55 PIN FUNCTIONS PINS THAT ARE THE SAME FOR ALL DIGITAL OUTPUT MODES AIN+ (Pin 1): Positive Differential Analog Input. AIN– (Pin 2): Negative Differential Analog Input. GND (Pin 3): ADC Power Ground. REFH (Pins 4, 5): ADC High Reference. Bypass to Pins 6, 7 with a 2.2μF ceramic capacitor and to ground with a 0.1μF ceramic capacitor. REFL (Pins 6, 7): ADC Low Reference. Bypass to Pins 4, 5 with a 2.2μF ceramic capacitor and to ground with a 0.1μF ceramic capacitor. PAR/SER (Pin 8): Programming Mode Selection Pin. Connect to ground to enable the serial programming mode. CS, SCK, SDI, SDO become a serial interface that control the A/D operating modes. Connect to VDD to enable the parallel programming mode where CS, SCK, SDI become parallel logic inputs that control a reduced set of the A/D 226114f 14 LTC2261-14 LTC2260-14/LTC2259-14 PIN FUNCTIONS operating modes. PAR/SER should be connected directly to ground or the VDD of the part and not be driven by a logic signal. VDD (Pins 9, 10, 40): 1.8V Analog Power Supply. Bypass to ground with 0.1μF ceramic capacitors. Pins 9 and 10 can share a bypass capacitor. ENC+ (Pin 11): Encode Input. Conversion starts on the rising edge. ENC – (Pin 12): Encode Complement Input. Conversion starts on the falling edge. CS (Pin 13): In serial programming mode, (PAR/SER = 0V), CS is the serial interface chip select input. When CS is low, SCK is enabled for shifting data on SDI into the mode control registers. In the parallel programming mode (PAR/SER = VDD), CS controls the clock duty cycle stabilizer. When CS is low, the clock duty cycle stabilizer is turned off. When CS is high, the clock duty cycle stabilizer is turned on. CS can be driven with 1.8V to 3.3V logic. SCK (Pin 14): In serial programming mode, (PAR/SER = 0V), SCK is the serial interface clock input. In the parallel programming mode (PAR/SER = VDD), SCK controls the digital output mode. When SCK is low, the full-rate CMOS output mode is enabled. When SCK is high, the double data rate LVDS output mode (with 3.5mA output current) is enabled. SCK can be driven with 1.8V to 3.3V logic. SDI (Pin 15): In serial programming mode, (PAR/SER = 0V), SDI is the serial interface data input. Data on SDI is clocked into the mode control registers on the rising edge of SCK. In the parallel programming mode (PAR/SER = VDD), SDI can be used to power down the part. When SDI is low, the part operates normally. When SDI is high, the part enters sleep mode. SDI can be driven with 1.8V to 3.3V logic. SDO (Pin 16): In serial programming mode, (PAR/SER = 0V), SDO is the optional serial interface data output. Data on SDO is read back from the mode control registers and can be latched on the falling edge of SCK. SDO is an open-drain NMOS output that requires an external 2k pull-up resistor to 1.8V-3.3V. If read back from the mode control registers is not needed, the pull-up resistor is not necessary and SDO can be left unconnected. In the parallel programming mode (PAR/SER = VDD), SDO is not used and should not be connected. OGND (Pin 25): Output Driver Ground. OVDD (Pin 26): Output Driver Supply. Bypass to ground with a 0.1μF ceramic capacitor. VCM (Pin 37): Common Mode Bias Output, Nominally Equal to VDD/2. VCM should be used to bias the common mode of the analog inputs. Bypass to ground with a 0.1μF ceramic capacitor. VREF (Pin 38): Reference Voltage Output. Bypass to ground with a 1μF ceramic capacitor, nominally 1.25V. SENSE (Pin 39): Reference Programming Pin. Connecting SENSE to VDD selects the internal reference and a ±1V input range. Connecting SENSE to ground selects the internal reference and a ±0.5V input range. An external reference between 0.625V and 1.3V applied to SENSE selects an input range of ±0.8 • VSENSE. FULL-RATE CMOS OUTPUT MODE All Pins Below Have CMOS Output Levels (OGND to OVDD) D0 to D13 (Pins 17-24, 29-34): Digital Outputs. D13 is the MSB. CLKOUT– (Pin 27): Inverted version of CLKOUT+. CLKOUT+ (Pin 28): Data Output Clock. The digital outputs normally transition at the same time as the falling edge of CLKOUT+. The phase of CLKOUT+ can also be delayed relative to the digital outputs by programming the mode control registers. DNC (Pin 35): Do not connect this pin. OF (Pin 36): Over/Under Flow Digital Output. OF is high when an overflow or underflow has occurred. DOUBLE DATA RATE CMOS OUTPUT MODE All Pins Below Have CMOS Output Levels (OGND to OVDD) D0_1 to D12_13 (Pins 18, 20, 22, 24, 30, 32, 34): Double Data Rate Digital Outputs. Two data bits are multiplexed onto each output pin. The even data bits (D0, D2, D4, D6, D8, D10, 226114f 15 LTC2261-14 LTC2260-14/LTC2259-14 PIN FUNCTIONS D12) appear when CLKOUT+ is low. The odd data bits (D1, D3, D5, D7, D9, D11, D13) appear when CLKOUT+ is high. Internal 100Ω Termination Resistor Between the Pins of Each LVDS Output Pair. CLKOUT– (Pin 27): Inverted version of CLKOUT+. D0_1–/D0_1+ to D12_13 –/D12_13+ (Pins 17/18, 19/20, 21/22, 23/24, 29/30, 31/32, 33/34): Double Data Rate Digital Outputs. Two data bits are multiplexed onto each differential output pair. The even data bits (D0, D2, D4, D6, D8, D10, D12) appear when CLKOUT+ is low. The odd data bits (D1, D3, D5, D7, D9, D11, D13) appear when CLKOUT+ is high. CLKOUT+ (Pin 28): Data Output Clock. The digital outputs normally transition at the same time as the falling and rising edges of CLKOUT+. The phase of CLKOUT+ can also be delayed relative to the digital outputs by programming the mode control registers. DNC (Pins 17, 19, 21, 23, 29, 31, 33, 35): Do not connect these pins. OF (Pin 36): Over/Under Flow Digital Output. OF is high when an overflow or underflow has occurred. DOUBLE DATA RATE LVDS OUTPUT MODE All Pins Below Have LVDS Output Levels. The Output Current Level is Programmable. There is an Optional CLKOUT–/CLKOUT+ (Pins 27/28): Data Output Clock. The digital outputs normally transition at the same time as the falling and rising edges of CLKOUT+. The phase of CLKOUT+ can also be delayed relative to the digital outputs by programming the mode control registers. OF–/OF+ (Pins 35/36): Over/Under Flow Digital Output. OF+ is high when an overflow or underflow has occurred. FUNCTIONAL BLOCK DIAGRAM AIN+ – AIN VCM INPUT S/H FIRST PIPELINED ADC STAGE SECOND PIPELINED ADC STAGE THIRD PIPELINED ADC STAGE FOURTH PIPELINED ADC STAGE VDD FIFTH PIPELINED ADC STAGE GND VDD/2 0.1μF VREF 1.25V REFERENCE SHIFT REGISTER AND CORRECTION 1μF RANGE SELECT SENSE REFH REF BUF REFL INTERNAL CLOCK SIGNALS OVDD OF D13 DIFF REF AMP MODE CONTROL REGISTERS CLOCK/DUTY CYCLE CONTROL • • • OUTPUT DRIVERS D0 CLKOUT + CLKOUT – REFH 0.1μF REFL OGND ENC+ ENC– 226114 F01 PAR/SER CS SCK SDI SDO 2.2μF 0.1μF 0.1μF Figure 1. Functional Block Diagram 226114f 16 LTC2261-14 LTC2260-14/LTC2259-14 APPLICATIONS INFORMATION CONVERTER OPERATION The LTC2261-14/LTC2260-14/LTC2259-14 are low power 14-bit 125Msps/105Msps/80Msps A/D converters that are powered by a single 1.8V supply. The analog inputs should be driven differentially. The encode input can be driven differentially, or single ended for lower power consumption. The digital outputs can be CMOS, double data rate CMOS (to halve the number of output lines), or double data rate LVDS (to reduce digital noise in the system.) Many additional features can be chosen by programming the mode control registers through a serial SPI port. See the Serial Programming Mode section. ANALOG INPUT The analog input is a differential CMOS sample-and-hold circuit (Figure 2). The inputs should be driven differentially around a common mode voltage set by the VCM output pin, which is nominally VDD/2. For the 2V input range, the inputs should swing from VCM – 0.5V to VCM + 0.5V. There should be 180° phase difference between the inputs. INPUT DRIVE CIRCUITS Input filtering If possible, there should be an RC lowpass filter right at the analog inputs. This lowpass filter isolates the drive circuitry from the A/D sample-and-hold switching, and also limits wideband noise from the drive circuitry. Figure 3 shows an example of an input RC filter. The RC component values should be chosen based on the application’s input frequency. Transformer Coupled Circuits Figure 3 shows the analog input being driven by an RF transformer with a center-tapped secondary. The center tap is biased with VCM, setting the A/D input at its optimal 50Ω 0.1μF LTC2261-14 VDD AIN+ 0.1μF RON 25Ω 10Ω CSAMPLE 3.5pF T1 1:1 25Ω AIN+ LTC2261-14 0.1μF 12pF 25Ω RON 25Ω 10Ω ANALOG INPUT 25Ω CPARASITIC 1.8pF VDD AIN– VCM CSAMPLE 3.5pF CPARASITIC 1.8pF 25Ω T1: MA/COM MABAES0060 RESISTORS, CAPACITORS ARE 0402 PACKAGE SIZE AIN– 226114 F03 Figure 3. Analog Input Circuit Using a Transformer. Recommended for Input Frequencies from 5MHz to VDD 1.2V 10k ENC+ ENC– 10k 1.2V 226114 F02 Figure 2. Equivalent Input Circuit 226114f 17 LTC2261-14 LTC2260-14/LTC2259-14 APPLICATIONS INFORMATION DC level. At higher input frequencies a transmission line balun transformer (Figures 4 to 6) has better balance, resulting in lower A/D distortion. Amplifier Circuits Figure 7 shows the analog input being driven by a high speed differential amplifier. The output of the amplifier is AC coupled to the A/D so the amplifier’s output common mode voltage can be optimally set to minimize distortion. At very high frequencies an RF gain block will often have lower distortion than a differential amplifier. If the gain block is single-ended, then a transformer circuit (Figures 4 to 6) should convert the signal to differential before driving the A/D. 50Ω VCM 0.1μF 0.1μF ANALOG INPUT AIN+ T2 T1 25Ω LTC2261-14 0.1μF 1.8pF 50Ω 0.1μF VCM 25Ω AIN– 0.1μF 226114 F05 0.1μF ANALOG INPUT AIN+ T2 T1 25Ω LTC2261-14 0.1μF T1: MA/COM MABA-007159-000000 T2: COILCRAFT WBC1-1LB RESISTORS, CAPACITORS ARE 0402 PACKAGE SIZE 4.7pF 0.1μF 25Ω AIN– Figure 5. Recommended Front-End Circuit for Input Frequencies from 170MHz to 270MHz 226114 F04 T1: MA/COM MABA-007159-000000 T2: MA/COM MABAES0060 RESISTORS, CAPACITORS ARE 0402 PACKAGE SIZE 50Ω Figure 4. Recommended Front-End Circuit for Input Frequencies from 70MHz to 170MHz VCM 0.1μF 0.1μF 2.7nH ANALOG INPUT AIN+ LTC2261-14 0.1μF 25Ω T1 0.1μF 25Ω 2.7nH AIN– T1: MA/COM ETC1-1-13 RESISTORS, CAPACITORS ARE 0402 PACKAGE SIZE 226114 F06 Figure 6. Recommended Front-End Circuit for Input Frequencies Above 270MHz 226114f 18 LTC2261-14 LTC2260-14/LTC2259-14 APPLICATIONS INFORMATION Reference The LTC2261-14/2260-14/2259-14 has an internal 1.25V voltage reference. For a 2V input range using the internal reference, connect SENSE to VDD. For a 1V input range using the external reference, connect SENSE to ground. For a 2V input range with an external reference, apply a 1.25V reference voltage to SENSE (Figure 9.) The VREF , REFH and REFL pins should be bypassed as shown in Figure 8. The 0.1μF capacitor between REFH and REFL should be as close to the pins as possible (not on the back side of the circuit board). LTC2261-14 VREF 1.25V The input range can be adjusted by applying a voltage to SENSE that is between 0.625V and 1.30V. The input range will then be 1.6 • VSENSE. HIGH SPEED DIFFERENTIAL 0.1μF AMPLIFIER ANALOG INPUT 200Ω 200Ω 25Ω 0.1μF AIN+ 0.625V RANGE DETECT AND CONTROL SENSE BUFFER INTERNAL ADC HIGH REFERENCE 0.1μF REFH LTC2261-14 + + – – 1.25V BANDGAP REFERENCE 1μF TIE TO VDD FOR 2V RANGE; TIE TO GND FOR 1V RANGE; RANGE = 1.6 • VSENSE FOR 0.65V < VSENSE < 1.300V VCM 5Ω 12pF 0.1μF 25Ω 2.2μF AIN– 226114 F07 0.1μF 0.8x DIFF AMP 0.1μF REFL Figure 7. Front-End Circuit Using a High Speed Differential Amplifier INTERNAL ADC LOW REFERENCE 226114 F08 Figure 8. Reference Circuit VREF 1μF LTC2261-14 1.25V EXTERNAL REFERENCE SENSE 1μF 226114 F09 Figure 9. Using an External 1.25V Reference 226114f 19 LTC2261-14 LTC2260-14/LTC2259-14 APPLICATIONS INFORMATION Encode Input The signal quality of the encode inputs strongly affects the A/D noise performance. The encode inputs should be treated as analog signals—do not route them next to digital traces on the circuit board. There are two modes of operation for the encode inputs: the differential encode mode (Figure 10) and the single-ended encode mode (Figure 11). The differential encode mode is recommended for sinusoidal, PECL or LVDS encode inputs (Figures 12, 13). The encode inputs are internally biased to 1.2V through 10k equivalent resistance. The encode inputs can be taken above VDD (up to 3.6V), and the common mode range is from 1.1V to 1.6V. In the differential encode mode, ENC– should stay at least 200mV above ground to avoid falsely triggering the single-ended encode mode. For good jitter performance ENC+ and ENC– should have fast rise and fall times. LTC2261-14 Clock Duty Cycle Stabilizer For good performance the encode signal should have a 50%(±5%) duty cycle. If the optional clock duty cycle stabilizer circuit is enabled, the encode duty cycle can vary from 30% to 70% and the duty cycle stabilizer will maintain a constant 50% internal duty cycle. If the encode signal changes frequency or is turned off, the duty cycle stabilizer circuit requires one hundred clock cycles to lock onto the input clock. The duty cycle stabilizer is enabled by mode control register A2 (serial programming mode), or by CS (parallel programming mode). 25Ω VDD DIFFERENTIAL COMPARATOR VDD The single-ended encode mode should be used with CMOS encode inputs. To select this mode, ENC – is connected to ground and ENC+ is driven with a square wave encode input. ENC+ can be taken above VDD (up to 3.6V) so 1.8V to 3.3V CMOS logic levels can be used. The ENC+ threshold is 0.9V. For good jitter performance ENC+ should have fast rise and fall times. 0.1μF ENC+ T1 1:4 100Ω D1 LTC2261-14 100Ω ENC– 15k ENC+ 0.1μF 226114 F12 T1: COILCRAFT WBC4 - 1WL D1: AVAGO HSMS - 2822 RESISTORS, CAPACITORS ARE 0402 PACKAGE SIZE ENC– 30k 226114 F10 Figure 12. Sinusoidal Encode Drive Figure 10. Equivalent Encode Input Circuit for Differential Encode Mode 0.1μF PECL OR LVDS CLOCK LTC2261-14 1.8V TO 3.3V 0V ENC+ ENC– ENC+ LTC2261-14 0.1μF ENC– 30k CMOS LOGIC BUFFER 226114 F11 226114 F13 Figure 13. PECL or LVDS Encode Drive Figure 11. Equivalent Encode Input Circuit for Single-Ended Encode Mode 226114f 20 LTC2261-14 LTC2260-14/LTC2259-14 APPLICATIONS INFORMATION For applications where the sample rate needs to be changed quickly, the clock duty cycle stabilizer can be disabled. If the duty cycle stabilizer is disabled, care should be taken to make the sampling clock have a 50%(±5%) duty cycle. The duty cycle stabilizer should not be used below 5Msps. When using Double Data Rate CMOS at high sample rates the SNR will degrade slightly (see Typical Performance Characteristics section). DDR CMOS is not recommended for sample frequencies above 100MHz. Double Data Rate LVDS Mode DIGITAL OUTPUTS Digital Output Modes The LTC2261-14/LTC2260-14/LTC2259-14 can operate in three digital output modes: full rate CMOS, double data rate CMOS (to halve the number of output lines), or double data rate LVDS (to reduce digital noise in the system). The output mode is set by mode control register A3 (serial programming mode), or by SCK (parallel programming mode). Note that double data rate CMOS cannot be selected in the parallel programming mode. Full-Rate CMOS Mode In full-rate CMOS mode the 14 digital outputs (D0-D13), overflow (OF), and the data output clocks (CLKOUT+, CLKOUT–) have CMOS output levels. The outputs are powered by OVDD and OGND which are isolated from the A/D core power and ground. OVDD can range from 1.1V to 1.9V, allowing 1.2V through 1.8V CMOS logic outputs. For good performance, the digital outputs should drive minimal capacitive loads. If the load capacitance is larger than 10pF a digital buffer should be used. Double Data Rate CMOS Mode In double data rate CMOS mode, two data bits are multiplexed and output on each data pin. This reduces the number of data lines by seven, simplifying board routing and reducing the number of input pins needed to receive the data. The 7 digital outputs (D0_1, D2_3, D4_5, D6_7, D8_9, D10_11, D12_13), overflow (OF), and the data output clocks (CLKOUT+, CLKOUT–) have CMOS output levels. The outputs are powered by OVDD and OGND which are isolated from the A/D core power and ground. OVDD can range from 1.1V to 1.9V, allowing 1.2V through 1.8V CMOS logic outputs. For good performance the digital outputs should drive minimal capacitive loads. If the load capacitance is larger than 10pF a digital buffer should be used. In double data rate LVDS mode, two data bits are multiplexed and output on each differential output pair. There are 7 LVDS output pairs (D0_1+/D0_1– through D12_13+/D12_13–) for the digital output data. Overflow (OF+/OF –) and the data output clock (CLKOUT+/CLKOUT–) each have an LVDS output pair. By default the outputs are standard LVDS levels: 3.5mA output current and a 1.25V output common mode voltage. An external 100Ω differential termination resistor is required for each LVDS output pair. The termination resistors should be located as close as possible to the LVDS receiver. The outputs are powered by OVDD and OGND which are isolated from the A/D core power and ground. In LVDS mode, OVDD must be 1.8V. Programmable LVDS Output Current In LVDS mode, the default output driver current is 3.5mA. This current can be adjusted by serially programming mode control register A3. Available current levels are 1.75mA, 2.1mA, 2.5mA, 3mA, 3.5mA, 4mA and 4.5mA. Optional LVDS Driver Internal Termination In most cases using just an external 100Ω termination resistor will give excellent LVDS signal integrity. In addition, an optional internal 100Ω termination resistor can be enabled by serially programming mode control register A3. The internal termination helps absorb any reflections caused by imperfect termination at the receiver. When the internal termination is enabled, the output driver current is increased by 1.6x to maintain about the same output voltage swing. Overflow Bit The overflow output bit (OF) outputs a logic high when the analog input is either overranged or underranged. The overflow bit has the same pipeline latency as the data bits. 226114f 21 LTC2261-14 LTC2260-14/LTC2259-14 APPLICATIONS INFORMATION Phase Shifting the Output Clock DATA FORMAT In full-rate CMOS mode the data output bits normally change at the same time as the falling edge of CLKOUT+, so the rising edge of CLKOUT+ can be used to latch the output data. In double data rate CMOS and LVDS modes the data output bits normally change at the same time as the falling and rising edges of CLKOUT+. To allow adequate setup-and-hold time when latching the data, the CLKOUT+ signal may need to be phase shifted relative to the data output bits. Most FPGAs have this feature; this is generally the best place to adjust the timing. Table 1 shows the relationship between the analog input voltage, the digital data output bits and the overflow bit. By default the output data format is offset binary. The 2’s complement format can be selected by serially programming mode control register A4. The LTC2261-14/LTC2260-14/LTC2259-14 can also phase shift the CLKOUT+/CLKOUT– signals by serially programming mode control register A2. The output clock can be shifted by 0°, 45°, 90° or 135°. To use the phase shifting feature the clock duty cycle stabilizer must be turned on. Another control register bit can invert the polarity of CLKOUT+ and CLKOUT–, independently of the phase shift. The combination of these two features enables phase shifts of 45° up to 315° (Figure 14). Table 1. Output Codes vs Input Voltage AIN+ – AIN– (2V Range) OF D13-D0 (OFFSET BINARY) D13-D0 (2’s COMPLEMENT) >1.000000V 1 11 1111 1111 1111 01 1111 1111 1111 +0.999878V 0 11 1111 1111 1111 01 1111 1111 1111 +0.999756V 0 11 1111 1111 1110 01 1111 1111 1110 +0.000122V 0 10 0000 0000 0001 00 0000 0000 0001 +0.000000V 0 10 0000 0000 0000 00 0000 0000 0000 –0.000122V 0 01 1111 1111 1111 11 1111 1111 1111 –0.000244V 0 01 1111 1111 1110 11 1111 1111 1110 –0.999878V 0 00 0000 0000 0001 10 0000 0000 0001 –1.000000V 0 00 0000 0000 0000 10 0000 0000 0000 ≤–1.000000V 1 00 0000 0000 0000 10 0000 0000 0000 ENC+ D0-D13, OF MODE CONTROL BITS PHASE SHIFT CLKINV CLKPHASE1 CLKPHASE0 0° 0 0 0 45° 0 0 1 90° 0 1 0 135° 0 1 1 180° 1 0 0 225° 1 0 1 270° 1 1 0 315° 1 1 1 CLKOUT+ 226114 F14 Figure 14. Phase Shifting CLKOUT 226114f 22 LTC2261-14 LTC2260-14/LTC2259-14 APPLICATIONS INFORMATION Digital Output Randomizer Alternate Bit Polarity Interference from the A/D digital outputs is sometimes unavoidable. Digital interference may be from capacitive or inductive coupling or coupling through the ground plane. Even a tiny coupling factor can cause unwanted tones in the ADC output spectrum. By randomizing the digital output before it is transmitted off chip, these unwanted tones can be randomized which reduces the unwanted tone amplitude. Another feature that reduces digital feedback on the circuit board is the alternate bit polarity mode. When this mode is enabled, all of the odd bits (D1, D3, D5, D7, D9, D11, D13) are inverted before the output buffers. The even bits (D0, D2, D4, D6, D8, D10, D12), OF and CLKOUT are not affected. This can reduce digital currents in the circuit board ground plane and reduce digital noise, particularly for very small analog input signals. The digital output is “randomized” by applying an exclusive-OR logic operation between the LSB and all other data output bits. To decode, the reverse operation is applied—an exclusive-OR operation is applied between the LSB and all other bits. The LSB, OF and CLKOUT outputs are not affected. The output randomizer is enabled by serially programming mode control register A4. When there is a very small signal at the input of the A/D that is centered around midscale, the digital outputs toggle between mostly 1s and mostly 0s. This simultaneous switching of most of the bits will cause large currents in the ground plane. By inverting every other bit, the alternate bit polarity mode makes half of the bits transition high while half of the bits transition low. To first order, this cancels current flow in the ground plane, reducing the digital noise. CLKOUT CLKOUT PC BOARD OF OF D13 D13/D0 D12 D2 RANDOMIZER ON D1 CLKOUT FPGA OF D13/D0 D12/D0 D13 • • • D12/D0 D2/D0 D1/D0 LTC2261-14 D12 D2/D0 • • • D2 D1/D0 D0 D1 D0 116114 F15 D0 D0 Figure 15. Functional Equivalent of Digital Output Randomizer 116114 F16 Figure 16. Unrandomizing a Randomized Digital Output Signal 226114f 23 LTC2261-14 LTC2260-14/LTC2259-14 APPLICATIONS INFORMATION The digital output is decoded at the receiver by inverting the odd bits (D1, D3, D5, D7, D9, D11, D13.) The alternate bit polarity mode is independent of the digital output randomizer—either, both or neither function can be on at the same time. When alternate bit polarity mode is on, the data format is offset binary and the 2’s complement control bit has no effect. The alternate bit polarity mode is enabled by serially programming mode control register A4. Digital Output Test Patterns To allow in-circuit testing of the digital interface to the A/D, there are several test modes that force the A/D data outputs (OF, D13-D0) to known values: REFH, and REFL. For the suggested values in Figure 8, the A/D will stabilize after 2ms. In nap mode the A/D core is powered down while the internal reference circuits stay active, allowing faster wake-up than from sleep mode. Recovering from nap mode requires at least 100 clock cycles. If the application demands very accurate DC settling then an additional 50μs should be allowed so the on-chip references can settle from the slight temperature shift caused by the change in supply current as the A/D leaves nap mode. Nap mode is enabled by mode control register A1 in the serial programming mode. All 1s: All outputs are 1 DEVICE PROGRAMMING MODES All 0s: All outputs are 0 The operating modes of the LTC2261-14 can be programmed by either a parallel interface or a simple serial interface. The serial interface has more flexibility and can program all available modes. The parallel interface is more limited and can only program some of the more commonly used modes. Alternating: Outputs change from all 1s to all 0s on alternating samples Checkerboard: Outputs change from 101010101010101 to 010101010101010 on alternating samples The digital output test patterns are enabled by serially programming mode control register A4. When enabled, the test patterns override all other formatting modes: 2’s complement, randomizer, alternate-bit-polarity. Output Disable The digital outputs may be disabled by serially programming mode control register A3. All digital outputs including OF and CLKOUT are disabled. The high impedance disabled state is intended for long periods of inactivity—it is too slow to multiplex a data bus between multiple converters at full speed. Sleep and Nap Modes The A/D may be placed in sleep or nap modes to conserve power. In sleep mode the entire A/D converter is powered down, resulting in 0.5mW power consumption. Sleep mode is enabled by mode control register A1 (serial programming mode), or by SDI (parallel programming mode). The amount of time required to recover from sleep mode depends on the size of the bypass capacitors on VREF , Parallel Programming Mode To use the parallel programming mode, PAR/SER should be tied to VDD. The CS, SCK and SDI pins are binary logic inputs that set certain operating modes. These pins can be tied to VDD or ground, or driven by 1.8V, 2.5V or 3.3V CMOS logic. Table 2 shows the modes set by CS, SCK and SDI. Table 2. Parallel Programming Mode Control Bits (PAR/SER = VDD) PIN DESCRIPTION CS Clock Duty Cycle Stabilizer Control Bit 0 = Clock Duty Cycle Stabilizer Off 1 = Clock Duty Cycle Stabilizer On SCK Digital Output Mode Control Bit 0 = Full-Rate CMOS Output Mode 1 = Double Data Rate LVDS Output Mode (3.5mA LVDS Current, Internal Termination Off) SDI Power Down Control Bit 0 = Normal Operation 1 = Sleep Mode 226114f 24 LTC2261-14 LTC2260-14/LTC2259-14 APPLICATIONS INFORMATION Serial Programming Mode To use the serial programming mode, PAR/SER should be tied to ground. The CS, SCK, SDI and SDO pins become a serial interface that program the A/D mode control registers. Data is written to a register with a 16-bit serial word. Data can also be read back from a register to verify its contents. Serial data transfer starts when CS is taken low. The data on the SDI pin is latched at the first 16 rising edges of SCK. Any SCK rising edges after the first 16 are ignored. The data transfer ends when CS is taken high again. The first bit of the 16-bit input word is the R/W bit. The next seven bits are the address of the register (A6:A0). The final eight bits are the register data (D7:D0). If the R/W bit is low, the serial data (D7:D0) will be written to the register set by the address bits (A6:A0). If the R/W bit is high, data in the register set by the address bits (A6:A0) will be read back on the SDO pin (see the timing diagrams). During a read back command the register is not updated and data on SDI is ignored. The SDO pin is an open-drain output that pulls to ground with a 200Ω impedance. If register data is read back through SDO, an external 2k pull-up resistor is required. If serial data is only written and read back is not needed, then SDO can be left floating and no pull-up resistor is needed. Table 3 shows a map of the mode control registers. Software Reset If serial programming is used, the mode control registers should be programmed as soon as possible after the power supplies turn on and are stable. The first serial command must be a software reset which will reset all register data bits to logic 0. To perform a software reset, bit D7 in the reset register is written with a logic 1. After the reset is complete, bit D7 is automatically set back to zero. Table 3. Serial Programming Mode Register Map REGISTER A0: RESET REGISTER (ADDRESS 00h) D7 D6 RESET Bit 7 X RESET D5 D4 D3 D2 D1 D0 X X X X X X Software Reset Bit 0 = Not Used 1 = Software Reset. All Mode Control Registers are Reset to 00h. This Bit is Automatically Set Back to Zero After the Reset is Complete Bits 6-0 Unused, Don’t Care Bits. REGISTER A1: POWER-DOWN REGISTER (ADDRESS 01h) D7 X D6 D5 D4 D3 D2 D1 D0 X X X X X PWROFF1 PWROFF0 Bits 7-2 Unused, Don’t Care Bits. Bits 1-0 PWROFF1:PWROFF0 00 = Normal Operation 01 = Nap Mode 10 = Not Used 11 = Sleep Mode Power Down Control Bits 226114f 25 LTC2261-14 LTC2260-14/LTC2259-14 APPLICATIONS INFORMATION REGISTER A2: TIMING REGISTER (ADDRESS 02h) D7 X D6 D5 D4 D3 D2 D1 D0 X X X CLKINV CLKPHASE1 CLKPHASE0 DCS Bits 7-4 Unused, Don’t Care Bits. Bit 3 CLKINV Output Clock Invert Bit 0 = Normal CLKOUT Polarity (As Shown in the Timing Diagrams) 1 = Inverted CLKOUT Polarity Bits 2-1 CLKPHASE1:CLKPHASE0 Output Clock Phase Delay Bits 00 = No CLKOUT Delay (As Shown in the Timing Diagrams) 01 = CLKOUT+/CLKOUT– Delayed by 45° (Clock Period • 1/8) 10 = CLKOUT+/CLKOUT– Delayed by 90° (Clock Period • 1/4) 11 = CLKOUT+/CLKOUT– Delayed by 135° (Clock Period • 3/8) Note: If the CLKOUT Phase Delay Feature is Used, the Clock Duty Cycle Stabilizer Must Also be Turned On Bit 0 DCS Clock Duty Cycle Stabilizer Bit 0 = Clock Duty Cycle Stabilizer Off 1 = Clock Duty Cycle Stabilizer On REGISTER A3: OUTPUT MODE REGISTER (ADDRESS 03h) D7 D6 D5 D4 D3 D2 D1 D0 X ILVDS2 ILVDS1 ILVDS0 TERMON OUTOFF OUTMODE1 OUTMODE0 Bit 7 Unused, Don’t Care Bit. Bits 6-4 ILVDS2:ILVDS0 LVDS Output Current Bits 000 = 3.5mA LVDS Output Driver Current 001 = 4.0mA LVDS Output Driver Current 010 = 4.5mA LVDS Output Driver Current 011 = Not Used 100 = 3.0mA LVDS Output Driver Current 101 = 2.5mA LVDS Output Driver Current 110 = 2.1mA LVDS Output Driver Current 111 = 1.75mA LVDS Output Driver Current Bit 3 TERMON LVDS Internal Termination Bit 0 = Internal Termination Off 1 = Internal Termination On. LVDS Output Driver Current is 1.6× the Current Set by ILVDS2:ILVDS0 Bit 2 OUTOFF Output Disable Bit 0 = Digital Outputs are Enabled 1 = Digital Outputs are Disabled and Have High Output Impedance Bits 1-0 OUTMODE1:OUTMODE0 Digital Output Mode Control Bits 00 = Full-Rate CMOS Output Mode 01 = Double Data Rate LVDS Output Mode 10 = Double Data Rate CMOS Output Mode 11 = Not Used 226114f 26 LTC2261-14 LTC2260-14/LTC2259-14 APPLICATIONS INFORMATION REGISTER A4: DATA FORMAT REGISTER (ADDRESS 04h) D7 X D6 D5 D4 D3 D2 D1 D0 X OUTTEST2 OUTTEST1 OUTTEST0 ABP RAND TWOSCOMP Bit 7-6 Unused, Don’t Care Bits. Bits 5-3 OUTTEST2:OUTTEST0 Digital Output Test Pattern Bits 000 = Digital Output Test Patterns Off 001 = All Digital Outputs = 0 011 = All Digital Outputs = 1 101 = Checkerboard Output Pattern. OF, D13-D0 Alternate Between 101 0101 1010 0101 and 010 1010 0101 1010 111 = Alternating Output Pattern. OF, D13-D0 Alternate Between 000 0000 0000 0000 and 111 1111 1111 1111 Note: Other Bit Combinations are not Used Bit 2 ABP Alternate Bit Polarity Mode Control Bit 0 = Alternate Bit Polarity Mode Off 1 = Alternate Bit Polarity Mode On Bit 1 RAND Data Output Randomizer Mode Control Bit 0 = Data Output Randomizer Mode Off 1 = Data Output Randomizer Mode On Bit 0 TWOSCOMP Two’s Complement Mode Control Bit 0 = Offset Binary Data Format 1 = Two’s Complement Data Format Note: ABP = 1 Forces the Output Format to be Offset Binary GROUNDING AND BYPASSING The LTC2261-14 requires a printed circuit board with a clean unbroken ground plane. A multilayer board with an internal ground plane is recommended. Layout for the printed circuit board should ensure that digital and analog signal lines are separated as much as possible. In particular, care should be taken not to run any digital track alongside an analog signal track or underneath the ADC. High quality ceramic bypass capacitors should be used at the VDD, OVDD, VCM, VREF, REFH and REFL pins. Bypass capacitors must be located as close to the pins as possible. Of particular importance is the 0.1μF capacitor between REFH and REFL. This capacitor should be on the same side of the circuit board as the A/D, and as close to the device as possible (1.5mm or less). Size 0402 ceramic capacitors are recommended. The larger 2.2μF capacitor between REFH and REFL can be somewhat further away. The VCM capacitor should be located as close to the pin as possible. To make space for this the capacitor on VREF can be further away or on the back of the PC board. The traces connecting the pins and bypass capacitors must be kept short and should be made as wide as possible. The analog inputs, encode signals, and digital outputs should not be routed next to each other. Ground fill and grounded vias should be used as barriers to isolate these signals from each other. HEAT TRANSFER Most of the heat generated by the LTC2261-14 is transferred from the die through the bottom-side exposed pad and package leads onto the printed circuit board. For good electrical and thermal performance, the exposed pad must be soldered to a large grounded pad on the PC board. 226114f 27 LTC2261-14 LTC2260-14/LTC2259-14 TYPICAL APPLICATIONS LTC2261 Schematic T2 MABAES0060 • R9 10Ω • SENSE R39 33.2Ω 1% ANALOG INPUT R10 10Ω R40 33.2Ω 1% C23 1μF R14 1k C51 4.7pF C17 1μF R16 100Ω R15 100Ω C12 0.1μF C13 1μF C19 0.1μF 40 39 38 37 VDD SENSE VREF VCM R27 10Ω 1 R28 10Ω 2 3 4 C15 0.1μF 5 C20 2.2μF 6 7 C21 0.1μF PAR/SER 8 9 10 C18 0.1μF 35 OF– 34 33 32 DIGITAL OUTPUTS 31 D13 D12 D11 D10 30 AIN+ D9 AIN– D8 GND CLKOUT+ 28 CLKOUT– 27 REFH U2 REFH LTC2261CUJ OVDD REFL OGND REFL D7 PAR/SER D6 VDD D5 VDD D4 GND 41 ENCODE CLOCK 36 OF+ ENC+ ENC– 11 12 CS 13 SCK SDI SDO 14 15 16 D0 17 D1 18 D2 19 D3 20 29 26 25 0VDD C37 0.1μF 24 23 22 21 DIGITAL OUTPUTS R13 100Ω 226114 TA02 SPI BUS 226114f 28 LTC2261-14 LTC2260-14/LTC2259-14 TYPICAL APPLICATIONS Top Side Silkscreen Top 226114 TA04 226114 TA03 Inner Layer 2 GND Inner Layer 3 226114 TA04 226114 TA06 226114f 29 LTC2261-14 LTC2260-14/LTC2259-14 TYPICAL APPLICATIONS Inner Layer 4 Inner Layer 5 Power 226114 TA08 226114 TA07 Bottom Side 226114 TA09 226114f 30 LTC2261-14 LTC2260-14/LTC2259-14 PACKAGE DESCRIPTION UJ Package 40-Lead Plastic QFN (6mm × 6mm) (Reference LTC DWG # 05-08-1728 Rev Ø) 0.70 ±0.05 6.50 ±0.05 5.10 ±0.05 4.42 ±0.05 4.50 ±0.05 (4 SIDES) 4.42 ±0.05 PACKAGE OUTLINE 0.25 ±0.05 0.50 BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 6.00 ± 0.10 (4 SIDES) 0.75 ± 0.05 R = 0.10 TYP R = 0.115 TYP 39 40 0.40 ± 0.10 PIN 1 TOP MARK (SEE NOTE 6) 1 2 PIN 1 NOTCH R = 0.45 OR 0.35 s 45° CHAMFER 4.50 REF (4-SIDES) 4.42 ±0.10 4.42 ±0.10 (UJ40) QFN REV Ø 0406 0.200 REF 0.00 – 0.05 NOTE: 1. DRAWING IS A JEDEC PACKAGE OUTLINE VARIATION OF (WJJD-2) 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.20mm ON ANY SIDE, IF PRESENT 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE 0.25 ± 0.05 0.50 BSC BOTTOM VIEW—EXPOSED PAD 226114f Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 31 LTC2261-14 LTC2260-14/LTC2259-14 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC1993-2 High Speed Differential Op Amp 800MHz BW, 70dBc Distortion at 70MHz, 6dB Gain LTC1994 Low Noise, Low Distortion Fully Differential Input/ Output Amplifier/Driver Low Distortion: –94dBc at 1MHz LTC2215 16-Bit, 65Msps, Low Noise ADC 700mW, 81.5dB SNR, 100dB SFDR, 64-Pin QFN LTC2216 16-Bit, 80Msps, Low Noise ADC 970mW, 81.3dB SNR, 100dB SFDR, 64-Pin QFN LTC2217 16-Bit, 105Msps, Low Noise ADC 1190mW, 81.2dB SNR, 100dB SFDR, 64-Pin QFN LTC2202 16-Bit, 10Msps, 3.3V ADC, Lowest Noise 140mW, 81.6dB SNR, 100dB SFDR, 48-Pin QFN LTC2203 16-Bit, 25Msps, 3.3V ADC, Lowest Noise 220mW, 81.6dB SNR, 100dB SFDR, 48-Pin QFN LTC2204 16-Bit, 40Msps, 3.3V ADC 480mW, 79dB SNR, 100dB SFDR, 48-Pin QFN LTC2205 16-Bit, 65Msps, 3.3V ADC 590mW, 79dB SNR, 100dB SFDR, 48-Pin QFN LTC2206 16-Bit, 80Msps, 3.3V ADC 725mW, 77.9dB SNR, 100dB SFDR, 48-Pin QFN LTC2207 16-Bit, 105Msps, 3.3V ADC 900mW, 77.9dB SNR, 100dB SFDR, 48-Pin QFN LTC2208 16-Bit, 130Msps, 3.3V ADC, LVDS Outputs 1250mW, 77.7dB SNR, 100dB SFDR, 64-Pin QFN LTC2209 16-Bit, 160Msps, 3.3V ADC, LVDS Outputs 1450mW, 77.1dB SNR, 100dB SFDR, 64-Pin QFN LTC2220 12-Bit, 170Msps ADC 890mW, 67.5dB SNR, 9mm × 9mm QFN Package LTC2220-1 12-Bit, 185Msps, 3.3V ADC, LVDS Outputs 910mW, 67.7dB SNR, 80dB SFDR, 64-Pin QFN LTC2224 12-Bit, 135Msps, 3.3V ADC, High IF Sampling 630mW, 67.6dB SNR, 84dB SFDR, 48-Pin QFN LTC2249 14-Bit, 80Msps ADC 230mW, 73dB SNR, 5mm × 5mm QFN Package LTC2250 10-Bit, 105Msps ADC 320mW, 61.6dB SNR, 5mm × 5mm QFN Package LTC2251 10-Bit, 125Msps ADC 395mW, 61.6dB SNR, 5mm × 5mm QFN Package LTC2252 12-Bit, 105Msps ADC 320mW, 70.2dB SNR, 5mm × 5mm QFN Package LTC2253 12-Bit, 125Msps ADC 395mW, 70.2dB SNR, 5mm × 5mm QFN Package LTC2254 14-Bit, 105Msps ADC 320mW, 72.5dB SNR, 5mm × 5mm QFN Package LTC2255 14-Bit, 125Msps, 3V ADC, Lowest Power 395mW, 72.5dB SNR, 88dB SFDR, 32-Pin QFN LTC2259-12/ LTC2260-12/ LTC2261-12 12-Bit, 80/105/125Msps 1.8V ADCs, Ultralow Power 87mW/103mW/124mW, 70.8dB SNR, 85dB SFDR, DDR LVDS/DDR CMOS/ CMOS Outputs, 6mm × 6mm QFN Package LTC2284 14-Bit, Dual, 105Msps, 3V ADC, Low Crosstalk 540mW, 72.4dB SNR, 88dB SFDR, 64-Pin QFN LTC2299 Dual 14-Bit, 80Msps ADC 230mW, 71.6dB SNR, 5mm x 5mm QFN Package LTC5517 40MHz to 900MHz Direct Conversion Quadrature Demodulator High IIP3: 21dBm at 800MHz, Integrated LO Quadrature Generator LTC5527 400MHz to 3.7GHz High Linearity Downconverting Mixer 24.5dBm IIP3 at 900MHz, 23.5dBm IIP3 at 3.5GHz, NF = 12.5dB, 50Ω Single-Ended RF and LO Ports LTC5557 400MHz to 3.8GHz High Linearity Downconverting Mixer 23.7dBm IIP3 at 2.6GHz, 23.5dBm IIP3 at 3.5GHz, NF = 13.2dB, 3.3V Supply Operation, Integrated Transformer LTC5575 800MHz to 2.7GHz Direct Conversion Quadrature Demodulator High IIP3: 28dBm at 900MHz, Integrated LO Quadrature Generator Integrated RF and LO Transformer LTC6400-20 1.8GHz Low Noise, Low Distortion Differential ADC Driver for 300MHz IF Fixed Gain 10V/V, 2.1nV√Hz Total Input Noise, 3mm × 3mm QFN-16 Package LTC6604-2.5/ LTC6604 -5/ LTC6604-10/ LTC6604-15 Dual Matched 2.5MHz, 5MHz, 10MHz, 15MHz Filter with ADC Driver Dual Matched 4th Order LP Filters with Differential Drivers. Low Noise, Low Distortion Amplifiers 226114f 32 Linear Technology Corporation LT 1208 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2008