CLC5955 11-bit, 55MSPS Broadband Monolithic A/D Converter April 2002 N CLC5955 11-bit, 55MSPS Broadband Monolithic A/D Converter General Description Features The CLC5955 is a monolithic 11-bit, 55MSPS analog-to-digital converter. The device has been optimized for use in IF-sampled digital receivers and other applications where high resolution, high sampling rate, wide dynamic range, low power dissipation, and compact size are required. The CLC5955 features differential analog inputs, low jitter differential universal clock inputs, a low distortion track-and-hold with 0-300MHz input bandwidth, a bandgap voltage reference, data valid clock output, TTL compatible CMOS (3.3V or 2.5V) programmable output logic, and a proprietary multistage quantizer. The CLC5955 is fabricated on the ABIC-V 0.8 micron BiCMOS process. • 55MSPS • Wide dynamic range SFDR: 74dBc SFDR w/dither: 85dBFS SNR: 64dB • IF sampling capability • Input bandwidth = 0-300MHz • Low power dissipation: 640mW • Very small package: 48-pin TSSOP • Single +5V supply • Data valid clock output • Programmable output levels: 3.3V or 2.5V The CLC5955 features a 74dBc spurious free dynamic range (SFDR) and a 64dB signal to noise ratio (SNR). The wideband track-and-hold allows sampling of IF signals to greater than 250MHz. The part produces two-tone, dithered, SFDR of 83dBFS at 75MHz input frequency. The differential analog input provides excellent common mode rejection, while the differential universal clock inputs minimize jitter. The 48-pin TSSOP package provides an extremely small footprint for applications where space is a critical consideration. The CLC5955 operates from a single +5V power supply. Operation over the industrial temperature range of -40°C to +85°C is guaranteed. National Semiconductor tests each part to verify compliance with the guaranteed specifications. Applications • • • • • • • • Cellular base-stations Digital communications Infrared/CCD imaging IF sampling Electro-optics Instrumentation Medical imaging High definition video N ME79TG CLC5955 CLC5957 N MTD ADC Block Diagram Actual Size First IF Receiver DAV Clock In IF Input AIn Q T/H Q Q IF Saw CLC5955 11-bit 55MSPS ADC ~ ~ BPF (150MHz typ.) Q CLC5903 DVGA (∆G = 42dB) Noise BPF 11 Dig. Tuner/ Filter AGC 20 DAV 3-bit (Gain Control) 11 Bit Align/Error Correct Decimation/filter = 190/0.8 Output BW = 50M/190 X 0.8 = 210KHz ADC Out Receiver SINAD vs. Input Amplitude Single Tone Output Spectrum w/Dither 90 0 Output Level (dBFS) SINAD dBc (BW = 216KHz) Fin = 25.3MHZ Fsample = 66MHz -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 60 50 40 30 20 10 0 0 4 8 12 16 20 24 Frequency (MHz) © 2002 National Semiconductor Corporation Printed in the U.S.A. 80 70 28 32 -125 -100 -75 -50 -25 0 Input (dBFS) http://www.national.com CLC5955 Electrical Characteristics (Vcc= +5V, 55MSPS; unless specified) (Tmin = -40°C, Tmax = +85°C) PARAMETERS RESOLUTION DIFF. INPUT VOLTAGE RANGE MAXIMUM CONVERSION RATE SNR SFDR CONDITIONS TEMP fin = 25MHz, Ain = -1dBFS fin = 25MHz, Ain = -1dBFS DYNAMIC PERFORMANCE large-signal bandwidth overvoltage recovery time effective aperture delay (Ta) aperture jitter Ain = -3dBFS Ain = 1.5FS (0.01%) 55 60 65 11 2.048 75 64 74 Bits V MSPS dBFS dBc 300 12 -0.41 0.3 MHz ns ns ps(rms) 65 64 63 64 64 dBFS dBFS dBFS dBFS dBFS 74 74 72 69 65 dBc dBc dBc dBc dBc +25°C +25°C 68 58 dBFS dBFS +25°C 85 dBFS +25°C 83 dBFS Full Full Full Full +25°C ±0.8 ±2.0 0 1.2 2.37 LSB LSB mV %FS V Full Full Full +25°C +25°C Full Full Full Full Full ANALOG INPUTS analog differential input voltage range analog input resistance (single ended) analog input resistance (differential) analog input capacitance (single-ended) 57 59 -30 2.2 Full Full Full Full ENCODE INPUTS (Universal) VIH VIL differential input swing DIGITAL OUTPUTS output voltage OUTLEV = 1 (open) OUTLEV = 0 (GND) TYP Full Full Full Full Full fin = 5MHz, Ain = -1dBFS fin = 5MHz, Ain = -1dBFS logic LOW logic HIGH logic HIGH POWER REQUIREMENTS +5V supply current Power dissipation VCC power supply rejection ratio UNITS MIN +25°C +25°C +25°C +25°C NOISE AND DISTORTION signal-to-noise ratio (w/o 50 harmonics) fin = 5.0MHz Ain = -1dBFS Ain = -1dBFS fin = 25MHz fin = 75MHz Ain = -3dBFS fin = 150MHz Ain = -15dBFS fin = 250MHz Ain = -15dBFS spurious-free dynamic range fin = 5.0MHz Ain = -1dBFS Ain = -1dBFS fin = 25MHz fin = 75MHz Ain = -3dBFS fin = 150MHz Ain = -15dBFS fin = 250MHz Ain = -15dBFS intermodulation distortion fin1 = 149.84MHz, fin2 = 149.7MHz Ain = -10dBFS fin1 = 249.86MHz, fin2 = 249.69MHz Ain = -10dBFS dithered performance spurious-free dynamic range Ain = -6dBFS fin = 19MHz intermodulation distortion Ain = -12dBFS fin1 = 74MHz, fin2 = 75MHz DC ACCURACY AND PERFORMANCE differential non-linearity integral non-linearity offset error gain error Vref RATINGS 0 0.2 +25°C +25°C +25°C 3.2 2.4 Full Full +25°C MAX 30 2.6 2.048 500 1000 2 +25°C +25°C +25°C NOTES 2 1 1 1 1 1 1 1 1 Vpp Ω Ω pF 5 V V V 3, 4 3, 4 3, 4 0.01 3.5 2.7 0.4 3.8 3.0 V V V 1 1 1 128 640 64 150 750 mA mW dB 1 1 Min/max ratings are based on product characterization and simulation. Individual parameters are tested as noted. Outgoing quality levels are determined from tested parameters. http://www.national.com 2 CLC5955 CLC5955 Electrical Characteristics (Vcc= +5V, 55MSPS; unless specified) (Tmin = -40°C, Tmax = +85°C) PARAMETERS CONDITIONS TIMING (CL =7pF DATA; 10pF DAV) max conversion rate (ENCODE) min conversion rate (ENCODE) pulse width high (ENCODE) 50% threshold pulse width low (ENCODE) 50% threshold ENCODE falling edge to DATA not valid ENCODE falling edge to DATA guaranteed valid rising ENCODE to rising DAV delay 50% threshold DATA setup time before rising DAV DATA hold time after rising DAV pipeline latency SYMB TEMP Full +25°C Full Full Full Full Full Full Full Full tP tM tDNV tDGV tDAV tS tH RATINGS MIN TYP 55 75 10 UNITS 9.1 9.1 8.3 8.3 tM-2.4 tP-1.6 NOTES MAX 17.8 12.6 3.0 2 MSPS MSPS ns ns ns ns ns ns ns clk cycle 1 3 3 3 3 3 3 3 Min/max ratings are based on product characterization and simulation. Individual parameters are tested as noted. Outgoing quality levels are determined from tested parameters. Notes 1) These parameters guaranteed by test. 2) Typical specifications are based on the mean test values of deliverable converters from the first three diffusion lots. 3) Values guaranteed based on characterization and simulation. 4) See page 8, Figure 3 for ENCODE Inputs circuit. Absolute Maximum Ratings positive supply voltage (Vcc) differential voltage between any two grounds analog input voltage range digital input voltage range output short circuit duration (one-pin to ground) junction temperature storage temperature range lead solder duration (+300°C) ESD tolerance human body model machine model Recommended Operating Conditions -0.5V to +6V <100mV GND to Vcc -0.5V to +Vcc infinite 175°C -65°C to 150°C 10sec positive supply voltage (Vcc) analog input voltage range operating temperature range +5V ±5% 2.048Vpp diff. -40°C to +85°C Package Thermal Resistance Package θJA θJC 48-pin TSSOP 56°C/W 16°C/W Reliability Information 2000V 200V Transistor count 5000 Note: Absolute maximum ratings are limiting values, to be applied individually, and beyond which the serviceability of the circuit may be impaired. Functional operability under any of these conditions is not necessarily implied. Exposure to maximum ratings for extended periods may affect device reliability. Ordering Information Model CLC5955MTDX CLC5955 Temperature Range -40°C to +85°C 3 Description 48-pin TSSOP (TNR 1000 pc reel) http://www.national.com N+1 N+2 N ANALOG INPUT Ta = -410ps ENCODE CLOCK N N+1 N+2 DAV CLOCK DATA OUTPUT N-3 N-2 N-1 CLC5955 Aperture Delay Diagram tM tP ENCODE tDNV Data [10…0] tDGV DATA VALID DATA VALID CLC5955 ENCODE to Data Timing Diagram tM tP ENCODE tDAV DAV CLC5955 ENCODE to DAV Timing Diagram DAV tS Data [10…0] tH DATA VALID CLC5955 DAV to Data Timing Diagram http://www.national.com 4 CLC5955 CLC5955 Typical Performance Characteristics (Vcc = +5V) SNR and SFDR vs. Input Frequency SNR and SFDR vs. Input Frequency 85 SNR (dBFS) and SFDR (dBc) SNR (dBFS) and SFDR (dBc) 85 80 75 70 SFDR 65 SNR 60 55 50 Fs = 66MSPS Ain = -3dBFS 45 40 80 75 70 SFDR 65 SNR 60 55 50 Fs = 52MSPS Ain = -3dBFS 45 40 0 100 300 200 0 100 Input Frequency (MHz) SNR and SFDR vs. Input Frequency SNR and SFDR vs. Sample Rate 90 SNR (dBc) and SFDR (dBc) SNR (dBFS) and SFDR (dBc) 85 80 75 70 SFDR SNR 65 60 55 50 Fs = 40.96MSPS Ain = -3dBFS 45 40 Fin = 24.5MHz 85 SFDR 80 75 70 SNR 65 60 55 50 0 100 40 300 200 50 Single Tone Output Spectrum 80 70 Single Tone Output Spectrum (w/Dither) 0 0 Fs = 66MSPS Ain = -1dBFS Fin = 24.5MHz -20 -30 -40 -50 -60 -70 -80 -20 -30 -40 -50 -60 -80 -90 -100 -100 5 10 15 20 25 30 Dither Signal = 500kHz @ - 28dBFS -70 -90 0 Fs = 66MSPS Ain = - 6dBFS Fin = 24.5MHz -10 Output Level (dBFS) -10 Output Level (dBFS) 60 Sample Rate (MSPS) Input Frequency (MHz) 35 0 5 10 Frequency (MHz) 15 20 25 30 35 Frequency (MHz) Differential Non-Linearity Integral Non-Linearity 2.0 4.0 Fs = 66MSPS Fin = 5MHz Fs = 66MSPS Fin = 5MHz 3.0 1.0 2.0 INL (LSBs) DNL (LSBs) 300 200 Input Frequency (MHz) 0 -1.0 1.0 0 -1.0 -2.0 -3.0 -2.0 -4.0 0 512 1024 1536 2048 0 Output Code CLC5955 512 1024 1536 2048 Output Code 5 http://www.national.com CLC5955 Typical Performance Characteristics (Vcc = +5V) SNR (dBc), SFDR (dBc), & THD (dBFS) SNR (dBc), SFDR (dBc), & THD (dBFS) SNR and SFDR vs. Input Amplitude (w/o Dither) 90 80 THD 70 60 50 SFDR 40 30 SNR Fin = 20MHz Fs = 66MSPS 20 10 -50 -40 -30 -20 SNR and SFDR vs. Input Amplitude (w/Dither) 90 THD 80 70 60 50 Fin = 20MHz Fs = 66MSPS 20 10 -50 -40 SNR (dBc), SFDR (dBc), & THD (dBFS) SNR (dBc), SFDR (dBc), & THD (dBFS) SNR and SFDR vs. Input Amplitude (w/o Dither) 90 80 THD 70 60 SNR SFDR 40 30 Fin = 75MHz Fs = 66MSPS 20 10 -50 -40 -30 -20 0 -10 SNR (dBc), SFDR (dBc), & THD (dBFS) 0 80 THD 70 60 50 SFDR SNR 40 30 Fin = 150MHz Fs = 66MSPS 20 10 -50 -40 -30 -20 -10 0 Input Amplitude (dBFS) Two Tone Output Spectrum (w/Dither) 90 0 80 -10 Output Level (dBFS) THD 70 SFDR 60 50 SNR 40 30 Fin = 250MHz Fs = 66MSPS Fs = 66MSPS F1 = 74.5MHz F2 = 75.5MHz -20 -30 -40 -50 -60 Dither Signal = 300KHz @ -28dBFS -70 -80 -90 10 -100 -50 -40 -30 -20 0 -10 0 5 Input Amplitude (dBFS) 10 15 20 25 30 Frequency (MHz) Two Tone Output Spectrum (w/Dither) Two Tone Output Spectrum (w/Dither) 0 0 Fs = 66MSPS F1 = 149.5MHz F2 = 150.5MHz -20 -30 -40 -50 -60 Dither Signal = 300KHz @ -28dBFS -70 -80 -20 -30 -40 -50 -60 -80 -90 -100 -100 5 10 15 20 25 Dither Signal = 500KHz @ -28dBFS -70 -90 0 Fs = 66MSPS F1 = 249.5MHz F2 = 251.5MHz -10 Output Level (dBFS) -10 Output Level (dBFS) -10 SNR and SFDR vs. Input Amplitude (w/o Dither) SNR and SFDR vs. Input Amplitude (w/o Dither) 0 30 Frequency (MHz) http://www.national.com -20 90 Input Amplitude (dBFS) 20 -30 Input Amplitude (dBFS) Input Amplitude (dBFS) 50 SNR 30 0 -10 SFDR 40 5 10 15 20 25 30 Frequency (MHz) 6 CLC5955 Physical Dimensions Symbol Min Max A – 1.10 A1 0.05 0.15 A2 0.80 1.05 b 0.17 0.27 b1 0.17 0.23 c 0.09 0.20 c1 0.09 0.16 D 12.40 12.60 E E1 e L L1 R1 Notes 2 8.1 BSC 6.00 6.20 2 0.50 BSC 0.50 0.75 1.00 REF 0.127 Notes: 1. All dimensions are in millimeters. 2. Dimensions D and E1 do not include mold protrusion. Allowable protrusion is 0.20mm per side. CLC5955 Pin Definitions GND 1 48 GND GND 2 47 GND GND 3 46 +DVCC GND 4 45 D10 (MSB) +AVCC 5 44 D9 +AVCC 6 43 D8 +AVCC 7 42 D7 GND 8 41 D6 ENCODE 9 40 D5 ENCODE 10 39 D4 GND 11 38 +DVCC GND 12 37 +DVCC AIN 13 36 GND AIN 14 35 GND GND 15 34 D3 +AVCC 16 33 D2 +AVCC 17 32 D1 +AVCC 18 31 D0 (LSB) GND 19 30 OGND GND 20 29 NC VCM 21 28 OUTLEV +AVCC 22 27 DAV GND 23 26 GND GND 24 25 GND CLC5955 CLC5955 AIN, AIN (Pins 13, 14) Differential input with a common mode voltage of +2.4V. The ADC full scale input is 1.024Vpp on each of the complimentary input signals. ENCODE, ENCODE (Pins 9, 10) Differential clock where ENCODE initiates a new data conversion cycle on each rising edge. Logic for these inputs are 50% duty cycle universal differential signal (>200mV). The clock input is internally biased to VCC/2 with a termination impedance of 2.5kΩ. D0-D10 (Pins 31-34, 39-45) Digital data outputs are CMOS and TTL compatible. D0 is the LSB and D10 is the MSB. MSB is inverted. Output coding is two’s complement. Current limited to source/sink 2.5mA typical. DAV (Pin 27) Data Valid Clock. Data is valid on rising edge. Current limited to source/sink 5mA typical. OUTLEV (Pin 28) Output Logic 3.3V or 2.5V option. Open = 3.3V, GND = 2.5V. VCM (Pin 21) Internal common mode voltage reference. Nominally +2.4V. Can be used for the input common mode voltage. This voltage is derived from an internal bandgap reference. VCM should be buffered when driving any external load. Failure to buffer this signal can cause errors in the internal bias currents. GND (Pins 1-4, 8, 11, 12, 15, 19, 20, 23-26, 35, 36, 47, 48) circuit ground. +AVCC (Pins 5-7, 16-18, 22,) +5V power supply for the analog section. Bypass to ground with a 0.1µF capacitor. +DVCC (Pins 37, 38, 46) +5V power supply for the digital section. Bypass to ground with a 0.1µF capacitor. NC (Pin 29) No connect. May be left open or grounded. OGND (Pin 30) Option ground. May be tied to GND or left floating. 7 http://www.national.com CLC5955 Applications Analog Inputs and Bias Figure 1 depicts the analog input and bias scheme. Each of the differential analog inputs are internally biased to a nominal voltage of 2.40 volts DC through a 500Ω resistor to a low impedance buffer. This enables a simple interface to a broadband RF transformer with a centertapped output winding that is decoupled to the analog ground. If the application requires the inputs to be DC coupled, the Vcm output can be used to establish the proper common -mode input voltage for the ADC. The Vcm voltage reference is generated from an internal bandgap source that is very accurate and stable. ENCODE Clock Inputs The CLC5955’s differential input clock scheme is compatible with all commonly used clock sources. Although small differential and single-ended signals are adequate, for best aperture jitter performance a low noise differential clock with a high slew rate is preferred. As depicted in Figure 3, both ENCODE clock inputs are internally biased to VCC/2 though a pair of 5KΩ resistors. The clock input buffer operates with any common-mode voltage between the supply and ground. VCCA ADC Bias Mirror Ain 5kΩ 5kΩ 5kΩ To T/H and ADC 500µΑ Ain 500Ω ENC 500Ω + 1.23V Bandgap Reference 5kΩ ENC 2KΩ 2.4V – Vcm BJT Current Mirror GNDA Figure 1: CLC5955 Bias Scheme Figure 3: CLC5955 ENCODE Clock Inputs The Vcm output may also be used to power down the ADC. When the Vcm pin is pulled above 3.5V, the internal bias mirror is disabled and the total current is reduced to less than 10mA. Figure 2 depicts how this function can be used. The diode is necessary to prevent the logic gate from altering the ADC bias value. The internal bias resistors simplify the clock interface to another center-tapped transformer as depicted in Figure 4. A low phase noise, RF synthesizer of moderate amplitude (1 - 4Vpp) can drive the ADC through this interface. ENC ~ ENC CLC5955 CLC5955 5V CMOS "1" = on "0" = off Vref Figure 4: Transformer Coupled Clock Scheme Figure 2: Power Shutdown Scheme http://www.national.com 8 CLC5955 Figures 5 shows the clock interface scheme for square wave clock sources. To ease user interface to subsequent digital circuitry, the CLC5955 has a data valid clock output (DAV). In order to match delays over IC processing variables, this digital output also uses the same output buffer as the data bits. The DAV clock output is simply a delayed version of the ENCODE input clock. Since the ADC output data change is slaved to the falling edge of the ENCODE clock, the rising DAV clock edge occurs near the center of the data valid window (or eye) regardless of the sampling frequency. ENC 0.01µF ENC 0.01µF CLC5955 Minimum Conversion Rate This ADC is optimized for high-speed operation. The internal bipolar track and hold circuits will cause droop errors at low sample rates. The point at which these errors cause a degradation of performance is listed on the specifications page as the minimum conversion rate. If a lower sample rate is desired, the ADC should be clocked at a higher rate, and the output data should be decimated. For example, to obtain a 10MSPS output, the ADC should be clocked at 20MHz, and every other output sample should be used. No significant power savings occurs at lower sample rates, since most of the power is used in analog circuits rather than digital circuits. Figure 5: TTL, 3V or 5V CMOS Clock Scheme VCCD .4Vref + - Controlled Current Output Buffer CML to CMOS Digital Signal + - 50Ω Digital Output 10kΩ Output Level GNDD Open = 3.3Vhi GND = 2.5Vhi Figure 6: CLC5955 Digital Outputs Digital Outputs and Level Select Figure 6 depicts the digital output buffer and bias used in the CLC5955. Although each of the eleven output bits uses a controlled current buffer to limit supply transients, it is recommended that parasitic loading of the outputs is minimized. Because these output transients are harmonically related to the analog input signal, excessive loading will degrade ADC performance at some frequencies. The logic high level is slaved to the internal 2.4 voltage reference. The OUTLEV control pin selects either a 3.3V or 2.5V logic high level. An internal pullup resistor selects the 3.3 volt level as the default when the OUTLEV pin is left open. Grounding the OUTLEV pin selects the 2.5V logic high level. CLC5955 9 http://www.national.com CLC5955 11-bit, 55MSPS Broadband Monolithic A/D Converter This is to make the last page rotate correctly! LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, a) are intended for surgical implant into the body, or b) support or sustain life, and whose failure to perform, when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. N National Semiconductor Corporation National Semiconductor Europe Tel: 1(800) 272-9959 Fax: 1(800) 737-7018 E-mail: [email protected] www.national.com Fax: +49 (0) 1 80-530 85 86 E-mail: europe.support.nsc.com Deutsch Tel: +49 (0) 1 69 9508 6208 English Tel: +44 (0) 870 24 0 2171 Francais Tel: +33 (0) 1 41 91 8790 National Semiconductor Asia Pacific Customer Response Group Tel: 65-2544466 Fax: 65-2504466 E-mail: [email protected] National Semiconductor Japan Ltd. Tel: 81-3-5639-7560 Fax: 81-3-5639-7507 National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications. http://www.national.com 10