KIT ATION EVALU E L B AVAILA 19-3591; Rev 0; 2/05 16-Bit, 250Msps, High-Dynamic-Performance, Dual DAC with LVDS Inputs ♦ 250Msps Output Update Rate ♦ Noise Spectral Density = -164dBFS/Hz at fOUT = 16MHz ♦ Excellent SFDR and IMD SFDR = 76dBc at fOUT = 16MHz (to Nyquist) SFDR = 71dBc at fOUT = 80MHz (to Nyquist) IMD = -90dBc at fOUT = 10MHz IMD = -72dBc at fOUT = 80MHz ♦ ACLR = 75dB at fOUT = 61MHz ♦ 2mA to 20mA Full-Scale Output Current ♦ LVDS-Compatible Digital and Clock Inputs ♦ On-Chip +1.20V Bandgap Reference ♦ Low 296mW Power Dissipation ♦ Compact 68 QFN-EP Package (10mm x 10mm) ♦ Evaluation Kit Available (MAX5878EVKIT) Ordering Information PART TEMP RANGE PINPACKAGE MAX5878EGK -40°C to +85°C 68 QFN-EP** 250Msps LVDS MAX5877* 14 250Msps LVDS MAX5878 16 250Msps LVDS B11P B12N B11N B10P B10N B9P B9N B8P B8N DVDD1.8 B7P B7N B6P B6N B5P B5N 47 B14P B1P 6 46 B15N B1N 7 45 B15P B0P 8 44 SELIQN B0N 9 43 SELIQP GND 10 42 XORP DVDD3.3 11 41 XORN GND 12 40 PD GND 13 39 TORB AVDD3.3 14 38 CLKP GND 15 37 CLKN REFIO 16 36 GND FSADJ 17 35 AVCLK MAX5878 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 AVDD1.8 12 5 GND MAX5876* B14N B2N AVDD3.3 CMOS 48 AVDD3.3 CMOS 200Msps 4 GND 200Msps 16 B13P B2P OUTIP 14 MAX5875 49 OUTIN MAX5874 3 GND CMOS B13N B3N GND 200Msps B12P 50 OUTQP 12 51 OUTQN LOGIC INPUTS 57 56 55 54 53 52 2 GND UPDATE RATE 63 62 61 60 59 58 B3P AVDD3.3 MAX5873 RESOLUTION (BITS) 67 66 65 64 1 AVDD3.3 PART 68 B4N GND Selector Guide B4P TOP VIEW AVDD1.8 *Future product—contact factory for availability. G6800-4 Pin Configuration Applications Base Stations: Single/Multicarrier UMTS, CDMA, GSM Communications: Fixed Broadband Wireless Access, Point-to-Point Microwave Direct Digital Synthesis (DDS) Cable Modem Termination Systems (CMTS) Automated Test Equipment (ATE) Instrumentation PKG CODE **EP = Exposed pad. DACREF The MAX5878 is an advanced 16-bit, 250Msps, dual digital-to-analog converter (DAC). This DAC meets the demanding performance requirements of signal synthesis applications found in wireless base stations and other communications applications. Operating from +3.3V and +1.8V supplies, this dual DAC offers exceptional dynamic performance such as 76dBc spurious-free dynamic range (SFDR) at fOUT = 16MHz and supports update rates of 250Msps, with a power dissipation of only 296mW. The MAX5878 utilizes a current-steering architecture that supports a 2mA to 20mA full-scale output current range, and allows a 0.1VP-P to 1VP-P differential output voltage swing. The device features an integrated +1.2V bandgap reference and control amplifier to ensure high-accuracy and low-noise performance. A separate reference input (REFIO) allows for the use of an external reference source for optimum flexibility and improved gain accuracy. The clock inputs of the MAX5878 accept both LVDS and LVPECL-compatible voltage levels. The device features an interleaved data input that allows a single LVDS bus to support both DACs. The MAX5878 is available in a 68-pin QFN package with an exposed paddle (EP) and is specified for the extended temperature range (-40°C to +85°C). Refer to the MAX5876* and MAX5877* data sheets for pin-compatible 12-bit and 14-bit versions of the MAX5878, respectively. Refer to the MAX5875 data sheet for a CMOS-compatible version of the MAX5878. Features QFN ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX5878 General Description MAX5878 16-Bit, 250Msps, High-Dynamic-Performance, Dual DAC with LVDS Inputs ABSOLUTE MAXIMUM RATINGS AVDD1.8, DVDD1.8 to GND, DACREF...................-0.3V to +2.16V AVDD3.3, DVDD3.3, AVCLK to GND, DACREF ........-0.3V to +3.9V REFIO, FSADJ to GND, DACREF..................................-0.3V to (AVDD3.3 + 0.3V) OUTIP, OUTIN, OUTQP, OUTQN to GND, DACREF..................-1V to (AVDD3.3 + 0.3V) CLKP, CLKN to GND, DACREF.............-0.3V to (AVCLK + 0.3V) B15P/B15N–B0P/B0N, XORN, XORP, SELIQN, SELIQP to GND, DACREF ..................-0.3V to (DVDD1.8 + 0.3V) TORB, PD to GND, DACREF ..............-0.3V to (DVDD3.3 + 0.3V) Continuous Power Dissipation (TA = +70°C) 68-Pin QFN-EP (derate 41.7mW/°C above +70°C) (Note 1) ............3333.3mW Thermal Resistance θJA (Note 1)...................................+24°C/W Operating Temperature Range ......................... -40°C to +85°C Junction Temperature .................................................... +150°C Storage Temperature Range ........................... -60°C to +150°C Lead Temperature (soldering, 10s) ............................... +300°C Note 1: Thermal resistors based on a multilayer board with 4 x 4 via array in exposed paddle area. Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (AVDD3.3 = DVDD3.3 = AVCLK = +3.3V, AVDD1.8 = DVDD1.8 = +1.8V, GND = 0, fCLK = 2 x fDAC, external reference VREFIO = +1.25V, output load 50Ω double-terminated, transformer-coupled output, IOUTFS = 20mA, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS STATIC PERFORMANCE Resolution 16 Bits Integral Nonlinearity INL Measured differentially ±3 LSB Differential Nonlinearity DNL Measured differentially ±2 LSB Offset Error OS -0.015 Full-Scale Gain Error GEFS Gain-Drift Tempco Full-Scale Output Current ±0.001 +0.015 ±10 Offset-Drift Tempco IOUTFS Output Compliance External reference -4.1 -0.6 Internal reference ±100 External reference ±50 (Note 3) 2 Single-ended +4.1 %FS ppm/°C 20 -0.5 %FS ppm/°C +1.1 mA V Output Resistance ROUT 1 MΩ Output Capacitance COUT 5 pF DYNAMIC PERFORMANCE Clock Frequency fCLK 2 500 MHz Output Update Rate fDAC 1 250 Msps Noise Spectral Density 2 fDAC = 150MHz fOUT = 16MHz, -12dBFS -164 fDAC = 250MHz fOUT = 80MHz, -12dBFS -161 _______________________________________________________________________________________ dBFS/ Hz 16-Bit, 250Msps, High-Dynamic-Performance, Dual DAC with LVDS Inputs (AVDD3.3 = DVDD3.3 = AVCLK = +3.3V, AVDD1.8 = DVDD1.8 = +1.8V, GND = 0, fCLK = 2 x fDAC, external reference VREFIO = +1.25V, output load 50Ω double-terminated, transformer-coupled output, IOUTFS = 20mA, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 2) PARAMETER SYMBOL CONDITIONS fDAC = 100MHz Spurious-Free Dynamic Range to Nyquist SFDR fDAC = 200MHz fDAC = 250MHz Spurious-Free Dynamic Range, 25MHz Bandwidth Two-Tone IMD SFDR MIN TYP fOUT = 1MHz, 0dBFS 94 fOUT = 1MHz, -6dBFS 87 fOUT = 1MHz, -12dBFS 81 fOUT = 10MHz, -12dBFS 81 fOUT = 30MHz, -12dBFS 79 fOUT = 10MHz, -12dBFS 75 fOUT = 16MHz, -12dBFS, TA ≥ +25oC 69 76 fOUT = 16MHz, -12dBFS 67 76 fOUT = 50MHz, -12dBFS 73 fOUT = 80MHz, -12dBFS 71 fOUT = 10MHz, -12dBFS 74 fOUT = 50MHz, -12dBFS 75 fOUT = 80MHz, -12dBFS 71 fOUT = 100MHz, -12dBFS 69 fDAC = 150MHz fOUT = 16MHz, -12dBFS 78 fDAC = 100MHz fOUT1 = 9MHz, -7dBFS; fOUT2 = 10MHz, -7dBFS -90 fDAC = 200MHz fOUT1 = 79MHz, -7dBFS; fOUT2 = 80MHz, -7dBFS -72 TTIMD MAX UNITS dBc dBc dBc Four-Tone IMD, 1MHz Frequency Spacing, GSM Model FTIMD fDAC = 150MHz fOUT = 16MHz, -12dBFS -80 dBc Adjacent Channel Leakage Power Ratio 3.84MHz Bandwidth, W-CDMA Model ACLR fDAC = 184.32MHz fOUT = 61.44MHz 75 dB 240 MHz Output Bandwidth BW-1dB (Note 4) INTER-DAC CHARACTERISTICS ∆Gain Gain Matching Gain-Matching Tempco Phase-Matching Tempco fOUT = DC -0.22 ∆Gain/°C +0.01 +0.22 dB ±20 ppm/°C fOUT = 60MHz ±0.25 ∆Phase/°C fOUT = 60MHz ±0.002 Degrees Degrees/ °C dB ∆Phase Phase Matching ±0.2 fOUT = DC - 80MHz Channel-to-Channel Crosstalk fCLK = 400MHz, fOUT = 50MHz, 0dBFS 86 REFERENCE Internal Reference Voltage Range VREFIO 1.14 1.2 1.26 V _______________________________________________________________________________________ 3 MAX5878 ELECTRICAL CHARACTERISTICS (continued) MAX5878 16-Bit, 250Msps, High-Dynamic-Performance, Dual DAC with LVDS Inputs ELECTRICAL CHARACTERISTICS (continued) (AVDD3.3 = DVDD3.3 = AVCLK = +3.3V, AVDD1.8 = DVDD1.8 = +1.8V, GND = 0, fCLK = 2 x fDAC, external reference VREFIO = +1.25V, output load 50Ω double-terminated, transformer-coupled output, IOUTFS = 20mA, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 2) PARAMETER Reference Input Compliance Range SYMBOL CONDITIONS VREFIOCR MIN TYP 0.125 MAX UNITS 1.260 V Reference Input Resistance RREFIO 10 kΩ Reference Voltage Drift TCOREF ±25 ppm/°C ANALOG OUTPUT TIMING (See Figure 4) Output Fall Time tFALL 90% to 10% (Note 5) 0.7 ns Output Rise Time tRISE 10% to 90% (Note 5) 0.7 ns Excluding data latency (Note 5) Output Propagation Delay tPD Glitch Impulse Output Noise nOUT 1.1 ns Measured differentially 1 pV•s IOUTFS = 2mA 30 IOUTFS = 20mA 30 pA/√Hz TIMING CHARACTERISTICS Data to Clock Setup Time tSETUP Referenced to rising edge of clock (Note 6) -1.2 Data to Clock Hold Time tHOLD Referenced to rising edge of clock (Note 6) 2.0 Data Latency ns ns Latency to I output 9 Latency to Q output 8 Clock Cycles Minimum Clock Pulse-Width High tCH CLKP, CLKN 0.9 ns Minimum Clock Pulse-Width Low tCL CLKP, CLKN 0.9 ns LVDS LOGIC INPUTS (B15P/B15N–B0P/B0N, XORN, XORP, SELIQN, SELIQP) Differential Input-Logic High VIH Differential Input-Logic Low VIL Common-Mode Voltage Range 100 -100 VCMR Differential Input Resistance RIN Input Capacitance CIN mV 1.125 (Note 7) mV 1.375 V 110 Ω 2.5 pF CMOS LOGIC INPUTS (PD, TORB) Input-Logic High VIH Input-Logic Low VIL Input Leakage Current IIN PD, TORB Internal Pulldown Resistance Input Capacitance 0.7 x DVDD3.3 -20 VPD = VTORB = 3.3V CIN V 1 0.3 x DVDD3.3 V +20 µA 1.5 MΩ 2.5 pF CLOCK INPUTS (CLKP, CLKN) Differential Input Voltage Swing 4 Sine wave >1.5 Square wave >0.5 _______________________________________________________________________________________ VP-P 16-Bit, 250Msps, High-Dynamic-Performance, Dual DAC with LVDS Inputs (AVDD3.3 = DVDD3.3 = AVCLK = +3.3V, AVDD1.8 = DVDD1.8 = +1.8V, GND = 0, fCLK = 2 x fDAC, external reference VREFIO = +1.25V, output load 50Ω double-terminated, transformer-coupled output, IOUTFS = 20mA, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 2) PARAMETER Differential Input Slew Rate External Common-Mode Voltage Range SYMBOL SRCLK CONDITIONS MIN (Note 8) VCOM TYP MAX UNITS >100 V/µs AVCLK / 2 ±0.3 V Input Resistance RCLK 5 kΩ Input Capacitance CCLK 2.5 pF POWER SUPPLIES Analog Supply Voltage Range Digital Supply Voltage Range Analog Supply Current AVDD3.3 3.135 3.3 3.465 AVDD1.8 1.710 1.8 1.890 DVDD3.3 3.135 3.3 3.465 DVDD1.8 1.710 1.8 1.890 fDAC = 250Msps, fOUT = 16MHz 52 56 Power-down 1 fDAC = 250Msps, fOUT = 16MHz 32 Power-down 1 IAVDD3.3 IAVDD1.8 Digital Supply Current IDVDD3.3 IDVDD1.8 Power Dissipation PDISS Power-Supply Rejection Ratio PSRR Note 2: Note 3: Note 4: Note 5: Note 6: Note 7: Note 8: Note 9: fDAC = 250Msps, fOUT = 16MHz 0.2 Power-down 1 fDAC = 250Msps, fOUT = 16MHz 36 Power-down 4 fDAC = 250Msps, fOUT = 16MHz 296 Power-down 16 AVDD3.3 = AVCLK = DVDD3.3 = +3.3V ±5% (Notes 8, 9) -0.1 V V mA µA 36 mA 1 mA 40 mA µA µA µA 324 mW µW +0.1 %FS/V Specifications at TA ≥ +25°C are guaranteed by production testing. Specifications at TA < +25°C are guaranteed by design. Nominal full-scale current IOUTFS = 32 x IREF. This parameter does not include update-rate depending effects of sin(x)/x filtering inherent in the MAX5878. Parameter measured single-ended into a 50Ω termination resistor. Not production tested. Guaranteed by design. No termination resistance between XORP and XORN. A differential clock input slew rate of >100V/µs is required to achieve the specified dynamic performance. Parameter defined as the change in midscale output caused by a ±5% variation in the nominal supply voltage. _______________________________________________________________________________________ 5 MAX5878 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (AVDD3.3 = DVDD3.3 = AVCLK = +3.3V, AVDD1.8 = DVDD1.8 = +1.8V, external reference, VREFIO = +1.25V, RL = 50Ω double-terminated, IOUTFS = 20mA, TA = +25°C, unless otherwise noted.) 80 -12dBFS -12dBFS SFDR (dBc) 40 20 -6dBFS 80 0dBFS 0dBFS 60 100 40 20 0 0 10 15 20 25 10 20 30 40 50 0 15 30 fOUT (MHz) SINGLE-TONE SFDR vs. OUTPUT FREQUENCY (fCLK = 200Msps) 80 100 -6dBFS 80 SFDR (dBc) -12dBFS 40 20 60 75 60 TWO-TONE IMD vs. OUTPUT FREQUENCY (1MHz CARRIER SPACING, fCLK = 100Msps) 0dBFS 0dBFS 45 fOUT (MHz) SINGLE-TONE SFDR vs. OUTPUT FREQUENCY (fCLK = 250Msps) MAX5878 toc04 -6dBFS 60 40 0 0 fOUT (MHz) 100 -12dBFS -60 -12dBFS 40 MAX5878 toc06 5 -70 TWO-TONE IMD (dBc) 0 60 20 MAX5878 toc05 SFDR (dBc) 0dBFS -6dBFS SFDR (dBc) 80 SINGLE-TONE SFDR vs. OUTPUT FREQUENCY (fCLK = 150Msps) MAX5878 toc02 -6dBFS 60 100 MAX5878 toc01 100 SINGLE-TONE SFDR vs. OUTPUT FREQUENCY (fCLK = 100Msps) MAX5878 toc03 SINGLE-TONE SFDR vs. OUTPUT FREQUENCY (fCLK = 50Msps) SFDR (dBc) MAX5878 16-Bit, 250Msps, High-Dynamic-Performance, Dual DAC with LVDS Inputs -6dBFS -80 -90 -100 20 -12dBFS 0 20 40 60 fOUT (MHz) 6 -110 0 0 80 100 0 25 50 75 fOUT (MHz) 100 125 5 10 15 20 25 fOUT (MHz) _______________________________________________________________________________________ 30 35 40 16-Bit, 250Msps, High-Dynamic-Performance, Dual DAC with LVDS Inputs fT1 fT2 -40 -60 2 x fT1 - fT2 2 x fT2 - fT1 -80 100 -60 -70 -6dBFS AOUT = -6dBFS MAX5878 toc09 -50 TWO-TONE IMD (dBc) OUTPUT POWER (dBFS) -20 -40 20mA 80 SFDR (dBc) fT1 = 28.9795MHz fT2 = 30.0049MHz MAX5878 toc08 BW = 12MHz MAX5878 toc07 0 SFDR vs. FULL-SCALE OUTPUT CURRENT (fCLK = 200MHz) TWO-TONE IMD vs. OUTPUT FREQUENCY (1MHz CARRIER SPACING, fCLK = 200Msps) TWO-TONE INTERMODULATION DISTORTION (fCLK = 100Msps) 10mA 5mA 60 40 -80 20 -90 -12dBFS 0 -100 -100 26 28 30 32 34 0 36 10 20 40 50 60 70 0 80 SFDR vs. TEMPERATURE (fCLK = 250Msps) 40 60 100 80 fOUT (MHz) DIFFERENTIAL NONLINEARITY vs. DIGITAL INPUT CODE INTEGRAL NONLINEARITY vs. DIGITAL INPUT CODE 4 MAX5878 toc11 3 MAX5878 toc10 AOUT = -6dBFS TA = +25°C 2 3 80 2 TA = -40°C 75 TA = +85°C DNL (LSB) INL (LSB) 1 SFDR (dBc) 20 fOUT (MHz) fOUT (MHz) 85 30 MAX5878 toc12 24 0 1 0 -1 -1 70 -2 -2 65 -3 -4 -3 0 25 50 75 fOUT (MHz) 100 125 0 16,384 32,768 49,152 DIGITAL INPUT CODE 65,536 0 16,384 32,768 49,152 65,536 DIGITAL INPUT CODE _______________________________________________________________________________________ 7 MAX5878 Typical Operating Characteristics (continued) (AVDD3.3 = DVDD3.3 = AVCLK = +3.3V, AVDD1.8 = DVDD1.8 = +1.8V, external reference, VREFIO = +1.25V, RL = 50Ω double-terminated, IOUTFS = 20mA, TA = +25°C, unless otherwise noted.) Typical Operating Characteristics (continued) (AVDD3.3 = DVDD3.3 = AVCLK = +3.3V, AVDD1.8 = DVDD1.8 = +1.8V, external reference, VREFIO = +1.25V, RL = 50Ω double-terminated, IOUTFS = 20mA, TA = +25°C, unless otherwise noted.) 260 240 220 0 220 215 180 50 100 150 200 250 fT1 = 29.9433MHz fT2 = 30.8266MHz fT3 = 31.9087MHz fT4 = 32.9123MHz -60 -100 210 3.135 3.465 3.3 26 28 30 -20 -30 ANALOG OUTPUT POWER (dBm) MAX5878 toc16 fCLK = 184.32MHz fCARRIER = 30.72MHz ACLR = +80dB 34 ACLR FOR W-CDMA MODULATION TWO CARRIER ACLR ACLR FOR W-CDMA MODULATION, SINGLE CARRIER ACLR -20 -30 -40 -50 -60 -70 -80 -90 -100 -110 -120 -130 32 fOUT (MHz) SUPPLY VOLTAGE (V) fCLK (Msps) ANALOG OUTPUT POWER (dBm) -40 -40 MAX5878 toc17 0 fT4 -80 INTERNAL REFERENCE 200 fT2 fT3 fT1 -20 EXTERNAL REFERENCE 225 BW = 12MHz MAX5878 toc15 AOUT = 0dBFS OUTPUT POWER (dBFS) 280 230 MAX5878 toc14 AOUT = 0dBFS POWER DISSIPATION (mW) MAX5878 toc13 300 FOUR-TONE POWER RATIO PLOT (fCLK = 150MHz) POWER DISSIPATION vs. SUPPLY VOLTAGE (fCLK = 100Msps, fOUT = 10MHz) POWER DISSIPATION vs. CLOCK FREQUENCY (fOUT = 10MHz) POWER DISSIPATION (mW) fCLK = 245.76Msps fCENTER = 30.72MHz ACLR = +78dB -50 -60 -70 -80 -90 -100 -110 -120 DC 92.16MHz 3.05MHz/div 9.2MHz/div ACLR FOR W-CDMA MODULATION TWO CARRIER ACLR -40 ACLR (dB) -50 -60 -70 -80 82.3 ALTERNATE 81.4 80.7 81 80.4 80 79.0 79.0 79 -90 -100 78 -110 77 -120 -130 -140 76 1 3.05MHz/div 8 82 ADJACENT 83.0 82.7 83 2 3 NUMBER OF CHANNELS _______________________________________________________________________________________ 4 MAX5878 toc19 fCLK = 184.32Msps fCENTER = 30.72MHz ACLR = +77dB W-CDMA BASEBAND ACLR 84 MAX5878 toc18 -30 ANALOG OUTPUT POWER (dBm) MAX5878 16-Bit, 250Msps, High-Dynamic-Performance, Dual DAC with LVDS Inputs 36 38 16-Bit, 250Msps, High-Dynamic-Performance, Dual DAC with LVDS Inputs PIN NAME 1 B4N Complementary Data Bit 4 FUNCTION 2 B3P Data Bit 3 3 B3N Complementary Data Bit 3 4 B2P Data Bit 2 5 B2N Complementary Data Bit 2 6 B1P Data Bit 1 7 B1N Complementary Data Bit 1 8 B0P Data Bit 0 (LSB) 9 B0N Complementary Data Bit 0 (LSB) 10, 12, 13, 15, 20, 23, 26, 27, 30, 33, 36 GND Ground 11 DVDD3.3 Digital Supply Voltage. Accepts a 3.135V to 3.465V supply voltage range. Bypass with a 0.1µF capacitor to GND. 14, 21, 22, 31, 32 AVDD3.3 Analog Supply Voltage. Accepts a 3.135V to 3.465V supply voltage range. Bypass each pin with a 0.1µF capacitor to GND. 16 REFIO Reference I/O. Output of the internal 1.2V precision bandgap reference. Bypass with a 1µF capacitor to GND. REFIO can be driven with an external reference source. See Table 1. 17 FSADJ Full-Scale Adjust Input. This input sets the full-scale output current of the DAC. For a 20mA fullscale output current, connect a 2kΩ resistor between FSADJ and DACREF. See Table 1. 18 DACREF Current-Set Resistor Return Path. Internally connected to GND. Do not use as an external ground connection. 19, 34 AVDD1.8 Analog Supply Voltage. Accepts a 1.71V to 1.89V supply voltage range. Bypass each pin with a 0.1µF capacitor to GND. 24 OUTQN Complementary Q-DAC Output. Negative terminal for current output. 25 OUTQP Q-DAC Output. Positive terminal for current output. 28 OUTIN Complementary I-DAC Output. Negative terminal for current output. 29 OUTIP I-DAC Output. Positive terminal for current output. 35 AVCLK Clock Supply Voltage. Accepts a 3.135V to 3.465V supply voltage range. Bypass with a 0.1µF capacitor to GND. 37 CLKN Complementary Converter Clock Input. Negative input terminal for differential converter clock. Internally biased to AVCLK / 2. 38 CLKP Converter Clock Input. Positive input terminal for differential converter clock. Internally biased to AVCLK / 2. 39 TORB Two’s-Complement/Binary Select Input. Set TORB to a CMOS-logic-high level to indicate a two’scomplement input format. Set TORB to a CMOS-logic-low level to indicate a binary input format. TORB has an internal pulldown resistor. _______________________________________________________________________________________ 9 MAX5878 Pin Description 16-Bit, 250Msps, High-Dynamic-Performance, Dual DAC with LVDS Inputs MAX5878 Pin Description (continued) PIN NAME 40 PD 41 XORN Complementary LVDS DAC Exclusive-OR Select Input. Set XORN high and XORP low to allow the data stream to pass unchanged to the DAC input. Set XORN low and XORP high to invert the DAC input data. If unused, connect XORN to DVDD1.8. 42 XORP LVDS DAC Exclusive-OR Select Input. Set XORN high and XORP low to allow the data stream to pass unchanged to the DAC input. Set XORN low and XORP high to invert the DAC input data. If unused, connect XORP to GND. 43 SELIQP LVDS DAC Select Input. Set SELIQN low and SELIQP high to direct data to the I-DAC outputs. Set SELIQP low and SELIQN high to direct data to the Q-DAC outputs. 44 SELIQN Complementary LVDS DAC Select Input. Set SELIQN low and SELIQP high to direct data to the I-DAC outputs. Set SELIQP low and SELIQN high to direct data to the Q-DAC outputs. Power-Down Input. Set PD to a CMOS-logic-high level to force the DAC into power-down mode. Set PD to a CMOS-logic-low level for normal operation. PD has an internal pulldown resistor. 45 B15P 46 B15N Complementary Data Bit 15 (MSB) 47 B14P Data Bit 14 48 B14N Complementary Data Bit 14 49 B13P Data Bit 13 50 B13N Complementary Data Bit 13 51 B12P Data Bit 12 52 B12N Complementary Data Bit 12 53 B11P Data Bit 11 54 B11N Complementary Data Bit 11 55 B10P Data Bit 10 56 B10N Complementary Data Bit 10 Data Bit 15 (MSB) 57 B9P 58 B9N Complementary Data Bit 9 59 B8P Data Bit 8 60 B8N 61 10 FUNCTION DVDD1.8 Data Bit 9 Complementary Data Bit 8 Digital Supply Voltage. Accepts a 1.71V to 1.89V supply voltage range. Bypass with a 0.1µF capacitor to GND. 62 B7P 63 B7N Data Bit 7 Complementary Data Bit 7 64 B6P Data Bit 6 65 B6N Complementary Data Bit 6 66 B5P Data Bit 5 67 B5N Complementary Data Bit 5 68 B4P — EP Data Bit 4 Exposed Pad. Must be connected to GND through a low-impedance path. ______________________________________________________________________________________ 16-Bit, 250Msps, High-Dynamic-Performance, Dual DAC with LVDS Inputs Architecture The MAX5878 high-performance, 16-bit, dual currentsteering DAC (Figure 1) operates with DAC update rates up to 250Msps. The converter consists of input registers and a demultiplexer for single-port operation, followed by a current-steering array. During operation, the input data registers demultiplex the single-port data bus. The current-steering array generates differential full-scale currents in the 2mA to 20mA range. An internal current-switching network, in combination with external 50Ω termination resistors, converts the differential output currents into dual differential output voltages with a 0.1V to 1V peak-to-peak output voltage range. An integrated DVDD1.8 DVDD3.3 +1.2V bandgap reference, control amplifier, and userselectable external resistor determine the data converter’s full-scale output range. Reference Architecture and Operation The MAX5878 supports operation with the internal +1.2V bandgap reference or an external reference voltage source. REFIO serves as the input for an external, low-impedance reference source. REFIO also serves as a reference output when the DAC operates in internal reference mode. For stable operation with the internal reference, decouple REFIO to GND with a 1µF capacitor. Due to its limited output drive capability, buffer REFIO with an external amplifier when driving large external loads. AVDD1.8 AVDD3.3 OUTIP TORB LATCH SELIQP XOR/ DECODE LATCH LATCH DAC OUTIN SELIQN LVDS RECEIVER DATA15– DATA0 LATCH XORP OUTQP XORN LATCH XOR/ DECODE LATCH LATCH DAC OUTQN AVCLK CLKP CLKN DACREF CLK INTERFACE +1.2V REFERENCE REFIO FSADJ MAX5878 POWER-DOWN BLOCK PD GND Figure 1. MAX5878 High-Performance, 16-Bit, Dual Current-Steering DAC ______________________________________________________________________________________ 11 MAX5878 Detailed Description MAX5878 16-Bit, 250Msps, High-Dynamic-Performance, Dual DAC with LVDS Inputs The MAX5878’s reference circuit (Figure 2) employs a control amplifier to regulate the full-scale current IOUTFS for the differential current outputs of the DAC. Calculate the full-scale output current as follows: IOUTFS = 32 × VREFIO 1 × 1 − 16 RSET 2 where I OUTFS is the full-scale output current of the DAC. R SET (located between FSADJ and DACREF) determines the amplifier’s full-scale output current for the DAC. See Table 1 for a matrix of different IOUTFS and RSET selections. Clock Inputs (CLKP, CLKN) The MAX5878 features flexible differential clock inputs (CLKP, CLKN) operating from a separate supply (AVCLK) to achieve optimum jitter performance. Drive the differential clock inputs from a single-ended or a differential clock source. For single-ended operation, drive CLKP with a logic source and bypass CLKN to GND with a 0.1µF capacitor. CLKP and CLKN are internally biased to AVCLK / 2. This facilitates the AC-coupling of clock sources directly to the device without external resistors to define the DC level. The dynamic input resistance from CLKP and CLKN to ground is 5kΩ. Analog Outputs (OUTIP, OUTIN, OUTQP, OUTQN) Each MAX5878 DAC outputs two complementary currents (OUTIP/N, OUTQP/N) that operate in a singleended or differential configuration. A load resistor converts these two output currents into complementary single-ended output voltages. A transformer or a differential amplifier configuration converts the differential voltage existing between OUTIP (OUTQP) and OUTIN (OUTQN) to a single-ended voltage. If not using a transformer, the recommended termination from the output is a 25Ω termination resistor to ground and a 50Ω resistor between the outputs. To generate a single-ended output, select OUTIP (or OUTQP) as the output and connect OUTIN (or OUTQN) to GND. SFDR degrades with single-ended operation or increased output swing. Figure 3 displays a simplified diagram of the internal output structure of the MAX5878. +1.2V REFERENCE Table 1. IOUTFS and RSET Selection Matrix Based on a Typical +1.200V Reference Voltage RSET (Ω) FULL-SCALE CURRENT IOUTFS (mA) CALCULATED 1% EIA STD 2 19.2k 19.1k 5 7.68k 7.5k 10 3.84k 3.83k 15 2.56k 2.55k 20 1.92k 1.91k AVDD CURRENT SOURCES 10kΩ CURRENT SWITCHES REFIO 1µF OUTIP FSADJ CURRENT-SOURCE ARRAY DAC IREF RSET OUTIN IOUT DACREF IREF = VREFIO / RSET OUTIN OUTIP GND Figure 2. Reference Architecture, Internal Reference Configuration 12 Figure 3. Simplified Analog Output Structure ______________________________________________________________________________________ IOUT 16-Bit, 250Msps, High-Dynamic-Performance, Dual DAC with LVDS Inputs MAX5878 CLKP-CLKN I0 DATAIN Q0 I1 Q1 I2 Q2 I3 Q3 SELIQP SELIQN tS tH I0 - 5 OUTI OUTQ I0 - 4 I0 - 3 I0 - 2 I0 - 6 Q0 - 6 Q0 - 5 Q0 - 4 tPD Q0 - 3 Q0 - 2 Figure 4. Timing Diagram Data Timing Relationship Figure 4 displays the timing relationship between digital LVDS data, clock, and output signals. The MAX5878 features a 2.0ns hold, a -1.2ns setup, and a 1.1ns propagation delay time. A nine (eight)-clock-cycle latency exists between CLKP/CLKN and OUTIP/OUTIN (OUTQP/OUTQN). LVDS-Compatible Digital Inputs (B15P/B15N–B0P/B0N, XORP, XORN, SELIQP, SELIQN) The MAX5878 latches B15P/N–B0P/N, XORP/N, and SELIQP/N data on the rising edge of the clock. A logichigh signal on SELIQP and a logic-low signal on SELIQN directs data onto the I-DAC inputs. A logic-low signal on SELIQP and a logic-high signal on SELIQN directs data onto the Q-DAC inputs. The MAX5878 features LVDS receivers on the bus input interface with internal 110Ω termination resistors. See Figure 5. XORP and XORN are not internally terminated. These LVDS inputs (B15P/N–B0P/N) allow for a low differential voltage swing with low constant power consumption. A 1.25V common-mode level and 250mV differential input swing can be applied to the B15P/N–B0P/N, XORP/N, and SELIQP/N inputs. The MAX5878 includes LVDS-compatible exclusive-OR inputs (XORP, XORN). Input data (all bits) is compared with the bits applied to XORP and XORN through exclusive-OR gates. Setting XORP high and XORN low inverts the input data. Setting XORP low and XORN high leaves the input data noninverted. By applying a previously encoded pseudo-random bit stream to the data input and applying decoding to XORP/XORN, the digital input data can be decorrelated from the DAC output, allowing for the troubleshooting of possible spurious or harmonic distortion degradation due to digital feedthrough on the PC board. If XOR functionality is not required, connect XORP to GND and XORN to DVDD1.8. ______________________________________________________________________________________ 13 MAX5878 16-Bit, 250Msps, High-Dynamic-Performance, Dual DAC with LVDS Inputs Table 2. DAC Output Code Table DIGITAL INPUT CODE OUT_P OUT_N 1000 0000 0000 0000 0 IOUTFS 0111 1111 1111 1111 0000 0000 0000 0000 IOUTFS / 2 IOUTFS / 2 1111 1111 1111 1111 0111 1111 1111 1111 IOUTFS 0 OFFSET BINARY TWO’S COMPLEMENT 0000 0000 0000 0000 Applications Information CMOS-Compatible Digital Inputs Input Data Format Select (TORB) The TORB input selects between two’s-complement or offset binary digital input data. Set TORB to a CMOSlogic-high level to indicate a two’s-complement input format. Set TORB to a CMOS-logic-low level to indicate a binary input format. Power-Down Operation (PD) The MAX5878 also features an active-high power-down mode that reduces the DAC’s digital current consumption from 36.2mA to less than 5µA and the analog current consumption from 84mA to less than 2µA. Set PD high to power down the MAX5878. Set PD low for normal operation. When powered down, the MAX5878 reduces the overall power consumption to less than 16µW. The MAX5878 requires 10ms to wake up from power-down and enter a fully operational state. The PD integrated pulldown resistor activates the MAX5878 if PD is left floating. CLK Interface The MAX5878 features a flexible differential clock input (CLKP, CLKN) with a separate supply (AV CLK ) to achieve optimum jitter performance. Use an ultra-low jitter clock to achieve the required noise density. Clock jitter must be less than 0.5psRMS for meeting the specified noise density. For that reason, the CLKP/CLKN input source must be designed carefully. The differential clock (CLKN and CLKP) input can be driven from a single-ended or a differential clock source. Differential clock drive is required to achieve the best dynamic performance from the DAC. For single-ended operation, drive CLKP with a low noise source and bypass CLKN to GND with a 0.1µF capacitor. Figure 6 shows a convenient and quick way to apply a differential signal created from a single-ended source (e.g., HP 8662A signal generator) and a wideband transformer. Alternatively, these inputs can be driven from a CMOS-compatible clock source; however, it is recommended to use sinewave or AC-coupled differential ECL/PECL or LVDS drive for best dynamic performance. WIDEBAND RF TRANSFORMER PERFORMS SINGLE-ENDED-TODIFFERENTIAL CONVERSION 0.1µF CLKP 25Ω B15P–B0P, SELIQP D Q TO DECODE LOGIC 110Ω B15N–B0N, SELIQN D SINGLE-ENDED CLOCK SOURCE (e.g., HP 8662A) TO DAC 1:1 25Ω 0.1µF Q CLKN MAX5878 CLOCK GND Figure 5. Simplified LVDS-Compatible Digital Input Structure 14 Figure 6. Differential Clock-Signal Generation ______________________________________________________________________________________ 16-Bit, 250Msps, High-Dynamic-Performance, Dual DAC with LVDS Inputs Grounding, Bypassing, and PowerSupply Considerations Use a pair of transformers (Figure 7) or a differential amplifier configuration to convert the differential voltage existing between OUTIP/OUTQP and OUTIN/OUTQN to a single-ended voltage. Optimize the dynamic performance by using a differential transformer-coupled output and limit the output power to <0dBm full scale. Pay close attention to the transformer core saturation characteristics when selecting a transformer for the MAX5878. Transformer core saturation can introduce strong 2nd-order harmonic distortion especially at low output frequencies and high signal amplitudes. For best results, center tap the transformer to ground. When not using a transformer, terminate each DAC output to ground with a 25Ω resistor. Additionally, place a 50Ω resistor between the outputs (Figure 8). Grounding and power-supply decoupling can strongly influence the MAX5878 performance. Unwanted digital crosstalk couples through the input, reference, power supply, and ground connections, and affects dynamic performance. High-speed, high-frequency applications require closely followed proper grounding and powersupply decoupling. These techniques reduce EMI and internal crosstalk that can significantly affect the MAX5878 dynamic performance. Use a multilayer printed circuit (PC) board with separate ground and power-supply planes. Run high-speed signals on lines directly above the ground plane. Keep digital signals as far away from sensitive analog inputs and outputs, reference input sense lines, commonmode input, and clock inputs as practical. Use a symmetric design of clock input and the analog output lines to minimize 2nd-order harmonic distortion components, thus optimizing the DAC’s dynamic performance. Keep digital signal paths short and run lengths matched to avoid propagation delay and data skew mismatches. For a single-ended unipolar output, select OUTIP (OUTQP) as the output and ground OUTIN (OUTQN) to GND. Driving the MAX5878 single-ended is not recommended since additional noise and distortion will be added. The distortion performance of the DAC depends on the load impedance. The MAX5878 is optimized for 50Ω differential double termination. It can be used with a transformer output as shown in Figure 7 or just one 25Ω resistor from each output to ground and one 50Ω resistor between the outputs (Figure 8). This produces a fullscale output power of up to -2dBm, depending on the output current setting. Higher termination impedance can be used at the cost of degraded distortion performance and increased output noise voltage. The MAX5878 requires five separate power-supply inputs for analog (AV DD1.8 and AV DD3.3 ), digital (DVDD1.8 and DVDD3.3), and clock (AVCLK) circuitry. All power-supply pins must be connected to their proper supply. Decouple each AVDD, DVDD, and AVCLK input pin with a separate 0.1µF capacitor as close to the device as possible with the shortest possible connection to the ground plane (Figure 9). Minimize the analog and digital load capacitances for optimized operation. Decouple all three power-supply voltages at the point they enter the PC board with tantalum or electrolytic 50Ω T2, 1:1 OUTIP/OUTQP DATA15–DATA0 100Ω MAX5878 16 VOUT, SINGLE-ENDED T1, 1:1 OUTIN/OUTQN 50Ω GND WIDEBAND RF TRANSFORMER T2 PERFORMS THE DIFFERENTIAL-TO-SINGLE-ENDED CONVERSION Figure 7. Differential-to-Single-Ended Conversion Using a Wideband RF Transformer ______________________________________________________________________________________ 15 MAX5878 Differential-to-Single-Ended Conversion Using a Wideband RF Transformer MAX5878 16-Bit, 250Msps, High-Dynamic-Performance, Dual DAC with LVDS Inputs capacitors. Ferrite beads with additional decoupling capacitors forming a pi-network could also improve performance. The analog and digital power-supply inputs AV DD3.3, AVCLK, and DVDD3.3 allow a +3.135V to +3.465V supply voltage range. The analog and digital power-supply inputs AVDD1.8 and DVDD1.8 allow a +1.71V to +1.89V supply voltage range. The MAX5878 is packaged in a 68-pin QFN-EP package, providing greater design flexibility, increased thermal efficiency, and optimized DAC AC performance. The EP enables the use of necessary grounding techniques to ensure highest performance operation. Thermal efficiency is not the key factor, since the MAX5878 features low-power operation. The exposed pad ensures a solid ground connection between the DAC and the PC board’s ground layer. The data converter die attaches to an EP lead frame with the back of this frame exposed at the package bottom surface, facing the PC board side of the package. This allows for a solid attachment of the package to the PC board with standard infrared reflow (IR) soldering techniques. A specially created land pattern on the PC board, matching the size of the EP (6mm x 6mm), ensures the proper attachment and grounding of the DAC. Designing vias into the land area and implementing large ground planes in the PC board design allow for the highest performance operation of the DAC. Use an array of at least 4 x 4 vias (≤0.3mm diameter per via hole and 1.2mm pitch between via holes) for this 68-pin QFN-EP package. Connect the MAX5878 exposed paddle to GND. Vias connect the land pattern to internal or external copper planes. Use as many vias as possible to the ground plane to minimize inductance. Static Performance Parameter Definitions Integral Nonlinearity (INL) Integral nonlinearity is the deviation of the values on an actual transfer function from either a best straight-line fit (closest approximation to the actual transfer curve) or a line drawn between the end points of the transfer function, once offset and gain errors have been nullified. For a DAC, the deviations are measured at every individual step. Differential Nonlinearity (DNL) Differential nonlinearity is the difference between an actual step height and the ideal value of 1 LSB. A DNL error specification of less than 1 LSB guarantees a monotonic transfer function. Offset Error The offset error is the difference between the ideal and the actual offset current. For a DAC, the offset point is the average value at the output for the two midscale digital input codes with respect to the full scale of the DAC. This error affects all codes by the same amount. Gain Error A gain error is the difference between the ideal and the actual full-scale output voltage on the transfer curve, after nullifying the offset error. This error alters the slope of the transfer function and corresponds to the same percentage error in each step. BYPASSING—DAC LEVEL AVDD1.8 AVDD3.3 0.1µF AVCLK 0.1µF OUTIP/OUTQP DATA15–DATA0 MAX5878 25Ω OUTIP/OUTQP DATA15–DATA0 OUTP 16 OUTIN/OUTQN 50Ω MAX5878 16 0.1µF 0.1µF 0.1µF OUTN OUTIN/OUTQN 25Ω GND DVDD1.8 DVDD3.3 *BYPASS EACH POWER-SUPPLY PIN INDIVIDUALLY. Figure 8. Differential Output Configuration 16 Figure 9. Recommended Power-Supply Decoupling and Bypassing Circuitry ______________________________________________________________________________________ 16-Bit, 250Msps, High-Dynamic-Performance, Dual DAC with LVDS Inputs Signal-to-Noise Ratio (SNR) For a waveform perfectly reconstructed from digital samples, the theoretical maximum SNR is the ratio of the fullscale analog output (RMS value) to the RMS quantization error (residual error). The ideal, theoretical minimum can be derived from the DAC’s resolution (N bits): SNRdB = 6.02dB x N + 1.76dB However, noise sources such as thermal noise, reference noise, clock jitter, etc., affect the ideal reading; therefore, SNR is computed by taking the ratio of the RMS signal to the RMS noise, which includes all spectral components minus the fundamental, the first four harmonics, and the DC offset. Noise Spectral Density The DAC output noise floor is the sum of the quantization noise and the output amplifier noise (thermal and shot noise). Noise spectral density is the noise power in 1Hz bandwidth, specified in dBFS/Hz. Spurious-Free Dynamic Range (SFDR) SFDR is the ratio of RMS amplitude of the carrier frequency (maximum signal components) to the RMS value of their next-largest distortion component. SFDR is usually measured in dBc and with respect to the carrier frequency amplitude or in dBFS with respect to the DAC’s full-scale range. Depending on its test condition, SFDR is observed within a predefined window or to Nyquist. quencies that digital filtering easily removes. Therefore, they are not as critical as 3rd-order IMDs. The two-tone IMD performance of the MAX5878 is tested with the two individual output tone levels set to at least -6dBFS and the four-tone performance was tested according to the GSM model at an output frequency of 16MHz and amplitude of -12dBFS. Adjacent Channel Leakage Power Ratio (ACLR) Commonly used in combination with wideband codedivision multiple-access (W-CDMA), ACLR reflects the leakage power ratio in dB between the measured power within a channel relative to its adjacent channel. ACLR provides a quantifiable method of determining out-of-band spectral energy and its influence on an adjacent channel when a bandwidth-limited RF signal passes through a nonlinear device. Settling Time The settling time is the amount of time required from the start of a transition until the DAC output settles its new output value to within the converter’s specified accuracy. Glitch Impulse A glitch is generated when a DAC switches between two codes. The largest glitch is usually generated around the midscale transition, when the input pattern transitions from 011...111 to 100...000. The glitch impulse is found by integrating the voltage of the glitch at the midscale transition over time. The glitch impulse is usually specified in pV•s. Two-/Four-Tone Intermodulation Distortion (IMD) The two-tone IMD is the ratio expressed in dBc (or dBFS) of the worst 3rd-order (or higher) IMD product(s) to either output tone; 2nd-order IMD products usually fall at fre- ______________________________________________________________________________________ 17 MAX5878 Dynamic Performance Parameter Definitions Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.) 68L QFN.EPS MAX5878 16-Bit, 250Msps, High-Dynamic-Performance, Dual DAC with LVDS Inputs PACKAGE OUTLINE, 68L QFN, 10x10x0.9 MM 1 C 21-0122 2 PACKAGE OUTLINE, 68L QFN, 10x10x0.9 MM 1 C 21-0122 2 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 18 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.