19-1170; Rev 0; 12/96 KIT ATION EVALU E L B A IL AVA 8-Bit, 750Msps Flash ADC ____________________________Features The MAX1151 is a parallel flash analog-to-digital converter (ADC) capable of digitizing full-scale (0V to -2V) inputs into 8-bit digital words at an update rate of 750Msps. The ECL-compatible outputs are demuxed into two separate output banks, each with differential data-ready outputs to ease the task of data capture. The MAX1151’s wide input bandwidth and low capacitance eliminate the need for external track/hold amplifiers for most applications. A proprietary decoding scheme reduces metastable errors to 1LSB. This device operates from a single -5.2V supply, with a nominal power dissipation of 5.5W. ♦ ♦ ♦ ♦ ♦ 1:2 Demuxed ECL-Compatible Outputs Wide Input Bandwidth: 900MHz Low Input Capacitance: 15pF Metastable Errors Reduced to 1LSB Single -5.2V Supply ________________________Applications Digital Oscilloscopes Data Acquisition Transient-Capture Applications ______________Ordering Information PART TEMP. RANGE PIN-PACKAGE MAX1151AIZS -20°C to +85°C 80 MQUAD MAX1151BIZS -20°C to +85°C 80 MQUAD Radar, EW, ECM Direct RF/IF Downconversion Pin Configuration appears on last page. _________________________________________________________Functional Diagram CLK NCLK CLOCK BUFFER DEMUX CLOCK BUFFER ANALOG VRT INPUT MAX1151 PREAMP COMPARATOR 255 152 64 D4 D2B D1B D0B D8A D7A • D3 • • 63 D5A D2 • • • 2 DRB (DATA READY) D8B (OVR) D7B (MSB) • D6 D5 NDRB (NOT DATA READY) • 1:2 DEMULTIPLEXER 127 256-BIT TO 8-BIT DECODER WITH METASTABLE ERROR CORRECTION VRM D7B • • D5B D7 (MSB) 151 128 D8B D8 (OVR) D2A D1 D6B ECL OUTPUT BUFFERS AND LATCHES 254 D5B BANK B D4B D3B D2B D1B D0B (LSB) NDRA (NOT DATA READY) DRA (DATA READY) D8A (OVR) D7A (MSB) D6A D5A BANK A D4A D3A D2A D1A D0A (LSB) D1A 1 D0 (LSB) D0A VFB ________________________________________________________________ Maxim Integrated Products For the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800 1 MAX1151 _______________General Description MAX1151 8-Bit, 750Msps Flash ADC ABSOLUTE MAXIMUM RATINGS Supply Voltages Negative Supply Voltage (VEE to GND) .............-7.0V to +0.5V Ground Voltage Differential .................................-0.5V to +0.5V Input Voltages Analog Input Voltage .............................................+0.5V to VEE Reference Input Voltage ........................................+0.5V to VEE Digital Input Voltage ..............................................+0.5V to VEE Reference Current (VRT to VRB)........................................35mA Digital Output Current ...........................................0mA to -28mA Operating Temperature Range ...........................-20°C to +85°C Case Temperature ...........................................................+125°C Junction Temperature ......................................................+150°C Lead Temperature (soldering, 10sec). ............................+300°C Storage Temperature Range .............................-65°C to +150°C 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 (VEE = -5.2V, VRB = -2.00V, VRM = -1.00V, VRT = 0.00V, fCLK = 750MHz, duty cycle = 50%, typical thermal impedance (θJC) = 4°C/W, Tj = TC = TA = +25°C.) (Note 1) PARAMETER CONDITIONS TEST LEVEL MIN Resolution MAX1151A TYP MAX MIN 8 MAX1151B TYP MAX 8 UNITS Bits DC ACCURACY Integral Nonlinearity fCLK = 100kHz I -1.0 1.0 -1.5 1.5 LSB Differential Nonlinearity fCLK = 100kHz I -0.85 0.95 -0.95 1.5 LSB No Missing Codes Guaranteed Guaranteed ANALOG INPUT Input Voltage Range Input Bias Current I VIN = 0V Input Resistance Input Capacitance Input Bandwidth VRB VRT I 0.75 VRB 2.0 0.75 VRT V 2.0 mA V 15 15 kΩ Over full input range V 15 15 pF Small signal V 900 900 Large signal V 500 500 Offset Error VRT IV -30 Offset Error VRB IV -30 Input Slew Rate V 30 -30 30 -30 5 MHz 30 30 mV mV 5 V/ns 80 Ω 30 MHz REFERENCE INPUT Ladder Resistance I Reference Bandwidth V 60 80 60 30 TIMING CHARACTERISTICS Maximum Sample Rate I Aperture Jitter V 750 750 2 MHz 2 Acquisition Time V CLK to DATA READY Delay IV 0.9 1.4 1.9 0.9 1.4 1.9 ns Clock to Data Delay IV 1.25 1.75 2.25 1.25 1.75 2.25 ns 2 250 ps 250 _______________________________________________________________________________________ ps 8-Bit, 750Msps Flash ADC (VEE = -5.2V, VRB = -2.00V, VRM = -1.00V, VRT = 0.00V, fCLK = 750MHz, duty cycle = 50%, typical thermal impedance (θJC) = 4°C/W, Tj = TC = TA = +25°C.) (Note 1) TEST LEVEL MIN fIN = 50MHz I 46 44 fIN = 250MHz I 44 42 fIN = 50MHz I -45 -43 fIN = 250MHz I -37 -35 Signal-to-Noise and Distortion fIN = 50MHz I 43 41 fIN = 250MHz I 36 34 Spurious-Free Dynamic Range fIN = 50MHz I 48 44 fIN = 250MHz I 40 36 Input High Voltage (CLK, NCLK) I -1.1 Input Low Voltage (CLK, NCLK) I Clock Pulse Width High (tPWH) I 0.67 0.5 0.67 0.5 ns Clock Pulse Width Low (tPWL) I 0.67 0.5 0.67 0.5 ns Clock Synchronous Input Currents V 2 µA -0.9 V PARAMETER CONDITIONS MAX1151A TYP MAX MIN MAX1151B TYP MAX UNITS DYNAMIC PERFORMANCE Signal-to-Noise Ratio (without harmonics) Total Harmonic Distortion dB dBc dB dB DIGITAL INPUTS -0.7 -1.8 -1.1 -1.5 -0.7 -1.8 2 V -1.5 V DIGITAL OUTPUTS Logic "1" Voltage I -1.1 -0.9 -1.1 Logic "0" Voltage I -1.8 POWER-SUPPLY REQUIREMENTS V 2.4 Supply Voltage (VEE) IV -5.2 -5.45 -5.2 -5.45 V Supply Current (IEE) I 1.05 1.2 1.05 1.2 A Power Dissipation I 5.5 6.25 5.5 6.25 W -4.95 -1.5 -1.8 -1.5 V 2.4 -4.95 Note 1: All parameters having min/max specifications are guaranteed. The Test Level column indicates the specific device testing actually performed during production and Quality Assurance inspection. Unless otherwise noted, all tests are pulsed tests; therefore, Tj = TC = TA. TEST LEVEL I TEST PROCEDURE 100% production tested at the specified temperature. II 100% production tested at TA = +25°C, and sample tested at the specified temperatures. III QA sample tested only at the specified temperatures. IV Parameter is guaranteed (but not tested) by design and characterization data. V Parameter is a typical value for information purposes only. VI 100% production tested at TA = +25°C. Parameter is guaranteed over specified temperature range. _______________________________________________________________________________________ 3 MAX1151 ELECTRICAL CHARACTERISTICS (continued) MAX1151 8-Bit, 750Msps Flash ADC ______________________________________________________________Pin Description PIN NAME 1, 2, 3 D2B, D3B, D4B Data Output Bank, Bits 2, 3, and 4 4, 5, 19, 20, 22, 23, 27, 28, 38, 39, 40, 46, 47, 49, 60, 67, 79 VEE Negative Supply, nominally -5.2V 6 D5B Data Output Bank B, Bit 5 7, 9, 11, 54, 56, 58, 69, 71, 73, 75, 77 DGND Digital Ground 8 D6B Data Output Bank B, Bit 6 10 D7B Data Output Bank B, Bit 7 (MSB) 12 D8B Data Output Bank B, Bit 8 (OVR) No Connection. Not internally connected. 13, 14, 31, 34, 41, 63, 64 N.C. 15-18, 25, 26, 29, 30, 36, 37, 44, 45, 51, 52 AGND Analog Ground 21 VRBF Reference-Voltage Force Bottom Reference-Voltage Sense Bottom 24 VRBS 32, 33 VIN Analog Input Voltage. Can be either voltage or sense. 35 VRM Reference-Voltage Middle, nominally -1V 42 VRTF Reference-Voltage Force Top 43 VRTS Reference-Voltage Sense Top 48 NCLK Inverse Clock Input 50 CLK Clock Input 53 DRA Data Ready Bank A 55 NDRA Not Data Ready Bank A 57 D0A 59, 61, 62, 65, 66, 68 D1A–D6A 70 D7A Data Output Bank A, Bit 7 (MSB) 72 D8A Data Output Bank A, Bit 8 (OVR) 74 NDRB 76 DRB Data Ready Bank B 78 D0B Data Output Bank B, Bit 0 (LSB) 80 D1B Data Output Bank B, Bit 1 _______________Detailed Description The MAX1151 is one of the fastest monolithic, 8-bit, parallel, flash analog-to-digital converters (ADCs) available today. The nominal conversion rate is 750Msps, and the analog bandwidth is in excess of 900MHz. A major advance over previous flash converters is the inclusion of 255 input preamplifiers between the reference ladder and input comparators (see Functional Diagram). This not only reduces clock transient kickback to the input and reference ladder but also reduces the effect of the input 4 FUNCTION Data Output Bank A, Bit 0 (LSB) Data Output Bank A, Bits 1–6 Not Data Ready Bank B signal’s dynamic state on the input comparators’ latching characteristics. The preamplifiers act as buffers to stabilize the input capacitance so that it remains constant over different input voltage and frequency ranges, making the part easier to drive than previous flash converters. The preamplifiers also add a gain of +2 to the input signal, so that each comparator has a wider overdrive or threshold range to trip into or out of the active state. This gain reduces metastable states that can cause errors at the output. _______________________________________________________________________________________ 8-Bit, 750Msps Flash ADC Typical Interface Circuit The circuit of Figure 1 shows a method of achieving the least error by correcting for integral linearity, inputinduced distortion, and power-supply/ground noise. This is achieved with the use of external reference-ladder tap connections, an input buffer, and supply decoupling. Contact the factory for the MAX1150/MAX1151 evaluation kit manual, which contains more details on interfacing the MAX1151. The function of each pin and external connections to other components are described in the following sections. VEE, AGND, DGND V EE is the supply pin with AGND as ground for the device. The power-supply pins should be bypassed as close to the device as possible with at least a 0.01µF ceramic capacitor. A 1µF tantalum can also be used for low-frequency suppression. DGND is the ground for the ECL outputs, and should be referenced to the output pulldown voltage and appropriately bypassed, as shown in Figure 1. VIN (Analog Input) There are two analog input pins that are tied to the same point internally. Either one may be used as an analog input sense, while the other is used for input force. This is convenient for testing the source signal to see if there is sufficient drive capability. The pins can also be tied together and driven by the same source. The MAX1151 is superior to similar devices due to a preamplifier stage before the comparators. This makes the device easier to drive because it has constant capacitance and induces less slew-rate distortion. CLK, NCLK (Clock Inputs) The clock inputs are designed to be driven differentially with ECL levels. The duty cycle of the clock should be kept at 50%, to avoid causing larger second harmonics. If this is not important to the intended application, duty cycles other than 50% may be used. D0 to D8, DR, NDR (A and B) The digital outputs can drive 50Ω to ECL levels when pulled down to -2V. When pulled down to -5.2V, the outputs can drive 130Ω to 1kΩ loads. All digital outputs are gray code, with the coding as shown in Table 1. Table 1. Output Coding VIN (V) D8 D7 . . . D0 0 1 -0.5 0 -1.0 0 -1.5 0 -2.0 0 10000000 10000001 10000011 • • • 10100001 10100000 11100000 • • • 11000001 11000000 01000000 • • • 01100001 01100000 00100000 • • • 00000011 00000001 00000000 MAX1151 The MAX1151 has true differential analog and digital data paths from the preamplifiers to the output buffers (current-mode logic) for reducing potential missing codes while rejecting common-mode noise. Signature errors are also reduced by careful layout of the analog circuitry. The device’s output drive capability can provide full ECL swings into 50Ω loads. VRBF, VRBS, VRTF, VRTS, VRM (Reference Inputs) There are two reference inputs and one external reference voltage tap. These are -2V (VRB force and sense), mid-tap (VRM), and AGND (VRT force and sense). The reference pins and tap can be driven by op amps (as shown in Figure 1), or VRM can be bypassed for limited temperature operation. These voltage inputs can be bypassed to AGND for further noise suppression, if desired. Thermal Management The typical thermal impedance (θCA) for the MQUAD package has been measured at θCA = 17°C/W, in still air with no heatsink. To ensure rated performance, we highly recommend using this device with a heatsink that can provide adequate air flow. We have found that a Thermalloy 17846 heatsink with a minimum air flow of 1 meter/second (200 linear feet per minute) provides adequate thermal performance under laboratory tests. Application-specific conditions should be taken into account to ensure that the device is properly heat sinked. _______________________________________________________________________________________ 5 MAX1151 8-Bit, 750Msps Flash ADC VIN VIN NDRB (NOT DATA READY) DRB (DATA READY) VIN D7B (MSB) D6B D5B VRTF R VRTS D4B D3B D2B D1B D0B (LSB) MAX1151 22Ω NDRA (NOT DATA READY) DRA (DATA READY) VRM U1 BANK B D8B (OVR) 50Ω D8A (OVR) ** D6A D5A R D4A D3A D2A VRBS 1N2907 -2.0V REFERENCE 22Ω U1 VRBF D1A D0A (LSB) ** -5.2V * * * * * * * * * * * CLK CLOCK IN U2 * * * * * * * * * * * NCLK 50Ω 50Ω 0.1µF VEE -2V PULL-DOWN (ANALOG) -2.0V PULL-DOWN (DIGITAL) DGND AGND L = Ferrite bead, DIGIKEY P98208BK or equivalent L ** * = 50Ω resistor * * = 10µF tantalum capacitor and 0.1µF chip capacitor -5.2V U1 = OP220 or equivalent with low offset/noise R = 1kΩ; 0.1% matched = AGND = DGND U2 = Motorola ECLinPS Lite, MC10EL16, differential receiver with 250ps (typ) propagation delay Figure 1. Typical Interface Circuit 6 _______________________________________________________________________________________ BANK A D7A (MSB) 8-Bit, 500Msps Flash ADC INPUT CIRCUIT N VIN N+6 N+4 1.3ns N+2 N+7 N+3 CLK NCLK DRA NDRA 1.4ns TYP DATA BANK A N-2 N N+2 N+ 4 1.75ns TYP DRB NDRB 1.4ns TYP DATA BANK B N+1 N-1 N+3 1.75ns TYP Figure 2. Timing Diagram OUTPUT CIRCUIT CLOCK INPUT AGND AGND AGND VIN N+5 N+1 DGND VR CLK NCLK DATA OUT VEE VEE Figure 3. Subcircuit Schematics _______________________________________________________________________________________ 7 MAX1151 Operation The MAX1151 has 255 preamplifier/comparator pairs; each is supplied with the voltage from VRT to VRB, divided equally by the resistive ladder as shown in the Functional Diagram. This voltage is applied to the positive input of each preamplifier/comparator pair. An analog input voltage applied at VIN is connected to the negative inputs of each preamplifier/comparator pair. The comparators are then clocked through each one’s individual clock buffer. When the CLK pin is in the low state, the master or input stage of the comparators compares the analog input voltage to the respective reference voltage. When CLK changes from low to high, the comparators are latched to the state prior to the clock transition and output logic codes in sequence from the top comparators, closest to VRT (0V), down to the point where the magnitude of the input signal changes sign (thermometer code). The output of each comparator is then registered into four 64-to-6 bit decoders when CLK is changed from high to low. At the output of the decoders is a set of four 7-bit latches that are enabled (track) when the clock changes from high to low. From here, the output of the latches is coded into six LSBs from four columns, and four columns are coded into two MSBs. Finally, eight ECL output latches and buffers are used to drive the external loads. The conversion takes one clock cycle from the input to the data outputs. 65 D4A 66 D5A 68 D6A 67 VEE 69 DGND 70 D7A 71 DGND 72 D8A 73 DGND 74 NDRB 75 DGND 76 DRB 77 DGND 78 D0B TOP VIEW 79 VEE 80 D1B ____________________________________________________________Pin Configuration D2B 1 64 N.C. D3B 2 63 N.C. D4B 3 62 D3A VEE 4 61 D2A VEE 5 60 VEE D5B 6 59 D1A DGND 7 58 DGND D6B 8 57 D0A DGND 9 56 DGND D7B 10 55 NDRA DGND 11 54 DGND D8B 12 53 DRA 52 AGND N.C. 14 51 AGND AGND 15 50 CLK AGND 16 49 VEE AGND 17 48 NCLK AGND 18 47 VEE VEE 19 46 VEE VEE 20 45 AGND VRBF 21 44 AGND VEE 22 43 VRTS VEE 23 42 VRTF VRBS 24 41 N.C. VEE 40 VEE 39 VEE 38 AGND 37 AGND 36 VRM 35 N.C. 34 VIN 33 N.C. 31 AGND 30 AGND 29 VEE 28 VEE 27 AGND 26 VIN 32 MAX1151 N.C. 13 AGND 25 MAX1151 8-Bit, 750Msps Flash ADC MQUAD 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. 8 ___________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600 © 1996 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.