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19-0586; Rev 0; 10/06 KIT ATION EVALU BLE AVAILA Ultrasound Variable-Gain Amplifier General Description Features 8-Channel Configuration High Integration for Ultrasound Imaging Applications Pin Compatible with the MAX2038 Ultrasound VGA Plus CW Doppler Beamformer Maximum Gain, Gain Range, and Output-Referred Noise Optimized for Interfacing with 12-Bit ADCs Maximum Gain of 29.5dB Total Gain Range of 42dB H 22nV/Hz Ultra-Low Output-Referred Noise at 5MHz Pin-for-Pin 10-Bit Compatibility Supported By MAX2035/MAX2036 0.25dB Absolute Gain Error Switchable Output VGA Clamp Eliminating ADC Overdrive Fully Differential VGA Outputs for Direct ADC Drive Variable Gain Range Achieves 42dB Dynamic Range -70dBc HD2 at VOUT = 1.5VP-P and fIN = 5MHz Two-Tone Ultrasound-Specific* IMD3 of -52dBc at VOUT = 1.5VP-P and fIN = 5MHz 120mW Consumption Per Channel *See the Ultrasound-Specific IMD3 Specification in the Applications Information section. MAX2037 The MAX2037 8-channel variable-gain amplifier (VGA) is designed for high linearity, high dynamic range, and low-noise performance targeting ultrasound imaging and Doppler applications. Each amplifier features differential inputs and outputs and a total gain range of typically 42dB. In addition, the VGAs offer very low output-referred noise performance suitable for interfacing with 12-bit ADCs. The MAX2037 VGA is optimized for less than 0.25dB absolute gain error to ensure minimal channel-to-channel ultrasound beamforming focus error. The device's differential outputs are designed to directly drive ultrasound ADCs through an external passive anti-aliasing filter. A switchable clamp is also provided at each amplifier's outputs to limit the output signals, thereby preventing ADC overdrive or saturation. Dynamic performance of the device is optimized to reduce distortion to support second-harmonic imaging. The device achieves a second-harmonic distortion specification of -70dBc at VOUT = 1.5VP-P and fIN = 5MHz, and an ultrasound-specific* two-tone third-order intermodulation distortion specification of -52dBc at VOUT = 1.5VP-P and fIN = 5MHz. The MAX2037 operates from a +5.0V power supply, consuming only 120mW/channel. The device is available in a 100-pin TQFP package with an exposed paddle. Electrical performance is guaranteed over a 0C to +70C temperature range. Applications Ultrasound Imaging Sonar Functional Diagram VCC VREF Ordering Information PART MAX2037CCQ-D TEMP RANGE 0C to +70C 0C to +70C 0C to +70C PIN-PACKAGE PKG CODE MAX2037 VG_CTL+ VG_CTLVG_IN1+ VGA VG_IN1* * * ** ** ** -12.5dB TO +29.5dB VG_CLAMP_MODE 50 VG_OUT1+ VG_OUT1* * * 100 TQFP-EP C100E-3 (14mm x 14mm) 100 TQFP-EP C100E-3 (14mm x 14mm) 100 TQFP-EP C100E-3 (14mm x 14mm) 100 TQFP-EP C100E-3 (14mm x 14mm) MAX2037CCQ-TD MAX2037CCQ+D 50 * * * VG_IN8+ VGA VG_IN8- 50 VG_OUT8+ VG_OUT8- 50 BIAS CIRCUITRY MAX2037CCQ+TD 0C to +70C EP = Exposed paddle. PD GND EXT_RES +Denotes lead-free package. T = Tape-and-reel package. D = Dry packing. 1 ________________________________________________________________ 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. Ultrasound Variable-Gain Amplifier MAX2037 ABSOLUTE MAXIMUM RATINGS VCC, VREF to GND .................................................-0.3V to +5.5V Any Other Pins to GND...............................-0.3V to (VCC + 0.3V) VGA Differential Input Voltage (VGIN_+ - VGIN_-)...........8.0VP-P Analog Gain-Control Input Differential Voltage (VG_CTL+ - VG_CTL-)...................................................8.0VP-P Continuous Power Dissipation (TA = +70C) 100-Pin TQFP (derated 45.5mW/C above +70C).........................3636.4mW Operating Temperature Range...............................0C to +70C Junction Temperature ......................................................+150C JC ...................................................................................+2C/W JA .................................................................................+22C/W Storage Temperature Range .............................-40C to +150C Lead Temperature (soldering, 10s) .................................+300C 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. DC ELECTRICAL CHARACTERISTICS (Figure 2, VCC = VREF = 4.75V to 5.25V, TA = 0C to +70C, GND = 0V, PD = 0, no RF signals applied, capacitance to GND at each of the VGA differential outputs is 60pF, differential capacitance across the VGA outputs is 10pF, RL = 1k. Typical values are at VCC = VREF = 5V, TA = +25C, unless otherwise noted.) (Note 1) PARAMETER Supply Voltage Range VCC External Reference Voltage Range Total Power Supply Current VCC Supply Current VREF Current Current Consumption per Amplifier Channel Differential Analog Control Voltage Range Differential Analog Control Common-Mode Voltage Analog Control Input Source/Sink Current LOGIC INPUTS CMOS Input High Voltage CMOS Input Low Voltage VIH VIL 2.0 0.8 V V VCM IVCC IREF Refers to VCC supply current Minimum gain Maximum gain 2.85 SYMBOL VCC VREF (Note 2) Refers to VCC supply current plus VREF current PD = 0 PD =1 CONDTIONS MIN 4.75 4.75 TYP 5 5 204 27 192 12 24 +2 -2 3.0 4.5 3.15 5 MAX 5.25 5.25 231 33 216 15 27 UNITS V V mA mA mA mA VP-P V mA 2 _______________________________________________________________________________________ Ultrasound Variable-Gain Amplifier AC ELECTRICAL CHARACTERISTICS (Figure 2, VCC = VREF = 4.75V to 5.25V, VCM = 2.85V to 3.15V, TA = 0C to +70C, GND = 0V, PD = 0, VG_CLAMP_MODE = 1, fRF = 5MHz, capacitance to GND at each of the VGA differential outputs is 60pF, differential capacitance across the VGA outputs is 10pF, RL = 1k. Typical values are at VCC = VREF = 5V, TA = +25C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL CONDITIONS Differential output capacitance is 10pF, capacitance to GND at each single-ended output is 60pF, RL = 1k No capacitive load RL = 1k Small Signal Bandwidth Differential Input Resistance Input Effective Capacitance Differential Output Resistance Maximum Gain Minimum Gain Gain Range Absolute Gain Error VGA Gain Response Time Input-Referred Noise TA = +25C, full gain range 0% to 100% 40dB gain change to within 1dB final value VG_CTL set for maximum gain, no input signal No input signal Output-Referred Noise VG_CTL set for +10dB of gain VOUT = 1.5VP-P, 1kHz offset f-1.3dB RIN CIN ROUT fRF = 10MHz, each input to ground VOUT = 1.5mVP-P, 3dB bandwidth, gain = 10dB 170 MIN TYP MAX UNITS MAX2037 Full-Scale Bandwidth f-1.3dB VOUT = 1.5VP-P, 1.3dB bandwidth, gain = 10dB 18 MHz 29 30 200 15 100 +29.5 -12.5 42 0.25 1 2 22 55 nV/Hz 1.0 230 MHz pF dB dB dB dB s nV/Hz VG_CLAMP_MODE = 1, VG_CTL set for +10dB of gain, fRF = 5MHz, VOUT = 1.5VP-P Second Harmonic HD2 VG_CLAMP_MODE = 1, VG_CTL set for +10dB of gain, fRF = 10MHz, VOUT = 1.5VP-P Third-Order Intermodulation Distortion IMD3 VG_CLT set for +10dB of gain, fRF1 = 5MHz, fRF2 = 5.01MHz, VOUT = 1.5VP-P (Note 3) -55 -70 dBc -65 -40 -52 dB _______________________________________________________________________________________ 3 Ultrasound Variable-Gain Amplifier MAX2037 AC ELECTRICAL CHARACTERISTICS (continued) (Figure 2, VCC = VREF = 4.75V to 5.25V, VCM = 2.85V to 3.15V, TA = 0C to +70C, GND = 0V, PD = 0, VG_CLAMP_MODE = 1, fRF = 5MHz, capacitance to GND at each of the VGA differential outputs is 60pF, differential capacitance across the VGA outputs is 10pF, RL = 1k. Typical values are at VCC = VREF = 5V, TA = +25C, unless otherwise noted.) (Note 1) PARAMETER Channel-to-Channel Crosstalk Maximum Output Voltage at Clamp ON SYMBOL CONDITIONS VOUT = 1VP-P differential, fRF = 10MHz, VG_CTL set for +10dB of gain VG_CLAMP_MODE = 0, VG_CTL set for +20dB of gain, 350mVP-P differential input VG_CLAMP_MODE = 1, VG_CTL set for +20dB of gain, 350mVP-P differential input MIN TYP -80 MAX UNITS dB VP-P differential 2.4 Maximum Output Voltage at Clamp OFF 2.8 VP-P differential Note 1: Specifications at TA = +25C and TA = +70C are guaranteed by production test. Specifications at TA = 0C are guaranteed by design and characterization. Note 2: Noise performance of the device is dependent on the noise contribution from the supply to VREF. Use a low noise supply for VREF. VCC and VREF can be connected together to share the same supply voltage if the supply for VCC exhibits low noise. Note 3: See the Ultrasound-Specific IMD3 Specification in the Applications Information section. Typical Operating Characteristics (Figure 2, VCC = VREF = 4.75V to 5.25V, GND = 0V, PD = 0, VG_CLAMP_MODE = 1, fRF = 5MHz, capacitance to GND at each of the VGA differential outputs is 60pF, differential capacitance across the VGA outputs is 10pF, RL = 1k, TA = 0C to +70C. Typical values are at VCC = VREF = 5V, TA = +25C, unless otherwise noted.) OVERDRIVE PHASE DELAY vs. FREQUENCY 4.5 OVERDRIVE PHASE DELAY (ns) 4.0 3.5 PSMR (dBc) 3.0 2.5 2.0 1.5 1.0 0.5 0 0 2.5 5.0 7.5 10.0 12.5 15.0 17.5 20.0 FREQUENCY (MHz) -100 0 25 50 75 100 125 150 175 200 FREQUENCY (kHz) VIN1 = 35mVP-P DIFFERENTIAL VIN2 = 87.5mVP-P DIFFERENTIAL GAIN = 20dB MAX2037toc01 POWER SUPPLY MODULATION RATIO MAX2037 toc02 TWO-TONE ULTRASOUND-SPECIFIC IMD3 vs. GAIN VOUT = 1VP-P DIFFERENTIAL -10 -20 MAX2037toc03 5.0 -40 -50 -60 VOUT = 1.5VP-P DIFFERENTIAL VMOD = 50mVP-P, fCARRIER = 5MHz, GAIN = 10dB 0 IMD3 (dBc) -30 f = 10MHz -40 -50 -60 f = 5MHz f = 2MHz -15 -5 5 15 25 35 -70 -80 -90 -70 -80 GAIN (dB) 4 _______________________________________________________________________________________ Ultrasound Variable-Gain Amplifier Typical Operating Characteristics (continued) (Figure 2, VCC = VREF = 4.75V to 5.25V, GND = 0V, PD = 0, VG_CLAMP_MODE = 1, fRF = 5MHz, capacitance to GND at each of the VGA differential outputs is 60pF, differential capacitance across the VGA outputs is 10pF, RL = 1k, TA = 0C to +70C. Typical values are at VCC = VREF = 5V, TA = +25C, unless otherwise noted.) SECOND HARMONIC DISTORTION vs. GAIN MAX2037toc04 MAX2037 THIRD HARMONIC DISTORTION vs. GAIN -10 -20 -30 HD3 (dBc) f = 12MHz f = 5MHz VOUT = 1VP-P DIFFERENTIAL MAX2037toc05 0 -10 -20 -30 HD2 (dBc) -40 -50 -60 -70 -80 -90 -100 -15 -5 5 15 25 f = 5MHz f = 2MHz f = 12MHz VOUT = 1VP-P DIFFERENTIAL 0 -40 -50 -60 -70 -80 -90 -100 f = 2MHz 35 -15 -5 5 15 25 35 GAIN (dB) GAIN (dB) OVERLOAD RECOVERY TIME MAX2037toc06 OVERLOAD RECOVERY TIME MAX2037toc07 f = 5MHz DIFFERENTIAL OUTPUT 1.0V/div f = 5MHz DIFFERENTIAL OUTPUT 2.0V/div DIFFERENTIAL INPUT 1.0V/div OUTPUT 1VP-P TO OVERLOAD AND BACK TO 1VP-P OUTPUT 100mVP-P TO OVERLOAD AND BACK TO 100mVP-P DIFFERENTIAL INPUT 2.0V/div 400ns/div 400ns/div CHANNEL-TO-CHANNEL CROSSTALK vs. GAIN MAX2037toc08 CHANNEL-TO-CHANNEL CROSSTALK vs. FREQUENCY -40 -50 CROSSTALK (dB) -60 -70 -80 -90 -100 -110 1 10 FREQUENCY (MHz) 100 VOUT = 1VP-P DIFFERENTIAL GAIN = 10dB, ADJACENT CHANNELS MAX2037toc10 -60 -65 -70 CROSSTALK (dB) -75 -80 -85 -90 -95 -100 -15 -5 5 15 25 VOUT = 1.5VP-P DIFFERENTIAL f = 10MHz, ADJACENT CHANNELS -30 35 GAIN (dB) _______________________________________________________________________________________ 5 Ultrasound Variable-Gain Amplifier MAX2037 Typical Operating Characteristics (continued) (Figure 2, VCC = VREF = 4.75V to 5.25V, GND = 0V, PD = 0, VG_CLAMP_MODE = 1, fRF = 5MHz, capacitance to GND at each of the VGA differential outputs is 60pF, differential capacitance across the VGA outputs is 10pF, RL = 1k, TA = 0C to +70C. Typical values are at VCC = VREF = 5V, TA = +25C, unless otherwise noted.) OUTPUT-REFERRED NOISE VOLTAGE vs. GAIN MAX2037toc11 GAIN vs. DIFFERENTIAL ANALOG CONTROL VOLTAGE (VG_CTL) MAX2037toc12 LARGE-SIGNAL BANDWIDTH vs. FREQUENCY 35 30 VOUT = 1.5VP-P DIFFERENTIAL VG_CTL = -2VP-P DIFFERENTIAL MAX2037toc13a OUTPUT-REFERRED NOISE VOLTAGE (nV/Hz) 50 f = 5MHz 40 35 f = 5MHz 25 15 GAIN (dB) 5 -5 40 GAIN (dB) 30 25 20 15 10 20 10 -15 -25 -15 -5 5 15 25 35 -2.5 -1.5 -0.5 0.5 1.5 2.5 GAIN (dB) VG_CTL (VP-P DIFFERENTIAL) 5 0 0.1 1 10 FREQUENCY (MHz) 100 1000 0 LARGE-SIGNAL BANDWIDTH vs. FREQUENCY MAX2037toc13b LARGE-SIGNAL BANDWIDTH vs. FREQUENCY MAX2037toc13c LARGE-SIGNAL BANDWIDTH vs. FREQUENCY 5 0 GAIN (dB) -5 -10 -15 -20 -25 -30 VOUT = 1.5VP-P DIFFERENTIAL VG_CTL = +1.5VP-P MAX2037toc13d 30 25 20 GAIN (dB) 20 15 10 GAIN (dB) 5 0 -5 -10 -15 -20 0.1 10 VOUT = 1.5VP-P DIFFERENTIAL VG_CTL = -1VP-P DIFFERENTIAL VOUT = 1.5VP-P DIFFERENTIAL VG_CTL = +0.6VP-P DIFFERENTIAL 15 10 5 0 -5 -10 0.1 1 10 FREQUENCY (MHz) 100 1000 1 10 FREQUENCY (MHz) 100 1000 0.1 1 10 FREQUENCY (MHz) 100 1000 LARGE-SIGNAL BANDWIDTH vs. FREQUENCY MAX2037toc13e LARGE-SIGNAL BANDWIDTH vs. FREQUENCY MAX2037toc13f HARMONIC DISTORTION vs. DIFFERENTIAL OUTPUT VOLTAGE -10 HARMONIC DISTORTION (dBc) -20 -30 -40 -50 -60 -70 -80 -90 -100 SECOND HARMONIC THIRD HARMONIC VOUT = 1VP-P DIFFERENTIAL f = 5MHz, GAIN = 10dB MAX2037toc14 5 0 -5 GAIN (dB) VOUT = 1VP-P DIFFERENTIAL VG_CTL = +1.7VP-P DIFFERENTIAL 0 -5 -10 GAIN (dB) -15 -20 -25 -30 -35 -40 0 VOUT = 0.5VP-P DIFFERENTIAL VG_CTL = +2VP-P DIFFERENTIAL -10 -15 -20 -25 -30 -35 0.1 1 10 FREQUENCY (MHz) 100 1000 0.1 1 10 FREQUENCY (MHz) 100 1000 0 0.5 1.0 1.5 2.0 2.5 3.0 DIFFERENTIAL OUTPUT VOLTAGE (VP-P) 6 _______________________________________________________________________________________ Ultrasound Variable-Gain Amplifier Typical Operating Characteristics (continued) (Figure 2, VCC = VREF = 4.75V to 5.25V, GND = 0V, PD = 0, VG_CLAMP_MODE = 1, fRF = 5MHz, capacitance to GND at each of the VGA differential outputs is 60pF, differential capacitance across the VGA outputs is 10pF, RL = 1k, TA = 0C to +70C. Typical values are at VCC = VREF = 5V, TA = +25C, unless otherwise noted.) HARMONIC DISTORTION vs. DIFFERENTIAL OUTPUT LOAD RESISTANCE MAX2037toc15 MAX2037 HARMONIC DISTORTION vs. DIFFERENTIAL OUTPUT LOAD CAPACITANCE MAX2037toc16 HARMONIC DISTORTION vs. FREQUENCY -10 HARMONIC DISTORTION (dBc) -20 -30 -40 -50 -60 -70 -80 -90 -100 SECOND HARMONIC THIRD HARMONIC VOUT = 1VP-P DIFFERENTIAL GAIN = 10dB MAX2037toc17 -40 -45 HARMONIC DISTORTION (dBc) -50 -55 -60 -65 -70 -75 -80 -85 -90 -95 -100 200 500 800 1100 1400 1700 SECOND HARMONIC VOUT = 1VP-P DIFFERENTIAL f = 5MHz, GAIN = 10dB THIRD HARMONIC -40 -45 HARMONIC DISTORTION (dBc) -50 -55 -60 -65 -70 -75 -80 -85 -90 -95 -100 SECOND HARMONIC VOUT = 1VP-P DIFFERENTIAL f = 5MHz, GAIN = 10dB THIRD HARMONIC 0 2000 5 25 45 65 85 105 0 10 20 30 40 50 DIFFERENTIAL OUTPUT LOAD () DIFFERENTIAL OUTPUT LOAD (pF) FREQUENCY (MHz) TWO-TONE ULTRASOUND-SPECIFIC IMD3 vs. FREQUENCY MAX2037toc18 GAIN ERROR HISTOGRAM 45 40 35 % OF UNITS 30 25 20 15 10 SAMPLE SIZE = 202 UNITS, fIN_ = 5MHz, GAIN = 10dB MAX2037 toc19 0 -10 -20 IMD3 (dBc) -30 -40 -50 -60 -70 0 5 10 15 20 VOUT = 1VP-P DIFFERENTIAL GAIN = 10dB 50 5 25 -0.40 -0.35 -0.30 -0.25 -0.20 -0.15 -0.10 -0.05 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 GAIN ERROR (dB) 0 FREQUENCY (MHz) OUTPUT COMMON-MODE OFFSET VOLTAGE vs. GAIN 15 OFFSET VOLTAGE (mV) 10 5 0 -5 -10 -15 -20 -15 -5 5 15 25 35 GAIN (dB) 100 80 60 0.1 MAX2037toc20 DIFFERENTIAL OUTPUT IMPEDANCE MAGNITUDE vs. FREQUENCY 180 160 MAX203toc21 20 200 |ZOUT| 140 120 1 10 100 FREQUENCY (MHz) _______________________________________________________________________________________ 7 Ultrasound Variable-Gain Amplifier MAX2037 Pin Description PIN 1, 2, 5, 6, 7, 10, 11, 12, 19, 20, 21, 24, 25, 26, 29, 30, 31, 34, 35, 36, 41, 43, 44, 45, 47, 48, 51, 55, 58, 59, 64, 65, 66, 69, 73, 76, 79, 80, 81, 83, 84, 85, 88-92, 96, 97, 98 3 4 8 9 13 14 15 16, 39, 42, 46, 54, 72, 82, 87 17 18 22 23 27 28 32 33 NAME FUNCTION GND Ground VGIN3VGIN3+ VGIN4VGIN4+ EXT_C1 EXT_C2 EXT_C3 VCC VGIN5VGIN5+ VGIN6VGIN6+ VGIN7VGIN7+ VGIN8VGIN8+ VGA Channel 3 Inverting Differential Input VGA Channel 3 Noninverting Differential Input VGA Channel 4 Inverting Differential Input VGA Channel 4 Noninverting Differential Input External Compensation. Connect a 4.7F capacitor to ground. External Compensation. Connect a 4.7F capacitor to ground. External Compensation. Connect a 4.7F capacitor to ground. 5V Power Supply. Bypass each VCC supply to ground with 0.1F capacitors as close to the pins as possible. VGA Channel 5 Inverting Differential Input VGA Channel 5 Noninverting Differential Input VGA Channel 6 Inverting Differential Input VGA Channel 6 Noninverting Differential Input VGA Channel 7 Inverting Differential Input VGA Channel 7 Noninverting Differential Input VGA Channel 8 Inverting Differential Input VGA Channel 8 Noninverting Differential Input 5V Reference Supply. Bypass to GND with a 0.1F capacitor as close to the pins as possible. Note that noise performance of the device is dependent on the noise contribution from the supply to VREF. Use a low noise supply for VREF. VCC and VREF can be connected together to share the same supply voltage if the supply for VCC exhibits low noise. External Resistor. Connect a 7.5k resistor to ground. Power-Down Switch. Drive PD high to set the device in power-down mode. Drive PD low for normal operation. VGA Channel 8 Noninverting Differential Output VGA Channel 8 Inverting Differential Output VGA Channel 7 Noninverting Differential Output VGA Channel 7 Inverting Differential Output VGA Channel 6 Noninverting Differential Output VGA Channel 6 Inverting Differential Output VGA Channel 5 Noninverting Differential Output 37, 93 VREF 38 40 49 50 52 53 56 57 60 EXT_RES PD VGOUT8+ VGOUT8VGOUT7+ VGOUT7VGOUT6+ VGOUT6VGOUT5+ 8 _______________________________________________________________________________________ Ultrasound Variable-Gain Amplifier Pin Description (continued) PIN 61 62 63 67 68 70 71 74 75 77 78 86 94 95 99 100 -- NAME VGOUT5VG_CTLVG_CTL+ VGOUT4+ VGOUT4VGOUT3+ VGOUT3VGOUT2+ VGOUT2VGOUT1+ VGOUT1VG_CLAMP_MODE VGIN1VGIN1+ VGIN2VGIN2+ EP FUNCTION VGA Channel 5 Inverting Differential Output VGA Analog Gain-Control Inverting Input VGA Analog Gain-Control Noninverting Input VGA Channel 4 Noninverting Differential Output VGA Channel 4 Inverting Differential Output VGA Channel 3 Noninverting Differential Output VGA Channel 3 Inverting Differential Output VGA Channel 2 Noninverting Differential Output VGA Channel 2 Inverting Differential Output VGA Channel 1 Noninverting Differential Output VGA Channel 1 Inverting Differential Output VGA Clamp Mode Enable. Drive VG_CLAMP_MODE low to enable VGA clamping. VGA output will be clamped at typically 2.4VP-P differential. Drive VG_CLAMP_MODE high to disable VGA clamp mode. VGA Channel 1 Inverting Differential Input VGA Channel 1 Noninverting Differential Input VGA Channel 2 Inverting Differential Input VGA Channel 2 Noninverting Differential Input Exposed paddle. Solder the exposed paddle to the ground plane using multiple vias. MAX2037 Detailed Description The MAX2037's VGAs are optimized for high linearity, high dynamic range, and low output noise performance, making this component ideal for ultrasoundimaging applications. The VGA paths also exhibit a channel-to-channel crosstalk of -80dB at 10MHz and an absolute gain error of less than 0.25dB for minimal channel-to-channel focusing error in an ultrasound system. Each VGA path includes circuitry for adjusting analog gain, an output buffer with differential output ports (VGOUT_+, VGOUT_-) for driving ADCs, and differential input ports (VGIN_+, VGIN_-) that are ideal for directly interfacing to the MAX2034 quad LNA. See the Functional Diagram for details. The VGA has an adjustable gain range from -12.5dB to +29.5dB, achieving a total dynamic range of typically 42dB. The VGA gain can be adjusted with the differential gain-control input VG_CTL+ and VG_CTL-. Set the differential gain-control input voltage at -2V for maximum gain and +2V for minimum gain. The differential analog control common-mode voltage is typically 3.0V. VGA Clamp A clamp is provided to limit the VGA output signals to avoid overdriving the ADC or to prevent ADC saturation. Set VG_CLAMP_MODE low to clamp the VGA differential outputs at 2.4VP-P. Set the VG_CLAMP_MODE high to disable the clamp. Power Down The device can also be powered down with PD. Set PD to logic-high for power-down mode. In power-down mode, the device draws a total supply current of 27mA. Set PD to a logic-low for normal operation Overload Recovery The device is also optimized for quick overload recovery for operation under the large input signal conditions that are typically found in ultrasound input buffer imaging applications. See the Typical Operating Characteristics for an illustration of the rapid recovery time from a transmit-related overload. _______________________________________________________________________________________ 9 Ultrasound Variable-Gain Amplifier MAX2037 Applications Information External Compensation External compensation is required for bypassing internal biasing circuitry. Connect, as close as possible, individual 4.7F capacitors from each pin EXT_C1, EXT_C2, and EXT_C3 (pin 13, 14, 15) to ground. Board Layout The pin configuration of the MAX2037 is optimized to facilitate a very compact physical layout of the device and its associated discrete components. A typical application for this device might incorporate several devices in close proximity to handle multiple channels of signal processing. The exposed paddle (EP) of the MAX2037's TQFP-EP package provides a low thermal-resistance path to the die. It is important that the PC board on which the MAX2037 is mounted be designed to conduct heat from the EP. In addition, provide the EP with a lowinductance path to electrical ground. The EP MUST be soldered to a ground plane on the PCB, either directly or through an array of plated via holes. External Bias Resistor An external resistor at EXT_RES is required to set the bias for the internal biasing circuitry. Connect, as close as possible, a 7.5k resistor from EXT_RES (pin 38) to ground. Analog Input and Output Coupling In typical applications, the MAX2037 is being driven from a low-noise amplifier (such as the MAX2034) and is typically driving a discrete differential anti-alias filter into an ADC (such as the MAX1436 octal ADC). The differential input impedance of the MAX2037 is typically 200. The differential outputs are capable of driving a differential load resistance of 1000. The output impedance is 100 differential. The differential outputs have a common-mode bias of approximately 3.0V. ACcouple these differential outputs if the next stage has a different common-mode input range. -25dB ULTRASOUND IMD3 Ultrasound-Specific IMD3 Specification Unlike typical communications specs, the two input tones are not equal in magnitude for the ultrasoundspecific IMD3 two-tone specification. In this measurement, f 1 represents reflections from tissue and f 2 represents reflections from blood. The latter reflections are typically 25dB lower in magnitude, and hence the measurement is defined with one input tone 25dB lower than the other. The IMD3 product of interest (f1 - (f2 - f1)) presents itself as an undesired Doppler error signal in ultrasound applications. See Figure 1. f1 - (f2 - f1) f1 f2 f2 + (f2 - f1) Figure 1. Ultrasound IMD3 Measurement Technique 10 ______________________________________________________________________________________ Ultrasound Variable-Gain Amplifier MAX2037 ZIN CONTROL D2, D1, D0 SINGLE CHANNEL MAX2034 SINGLE CHANNEL +V VG_CTL+ VG_CTL18nF 100nF 100nF VGIN_+ VGIN_100nF VGA 50 50 100nF VG_OUT_+ VG_OUT_100nF TO A SINGLE CHANNEL OF MAX2037 VIN MAX1436 ADC 100nF -V Figure 2. Typical Per-Channel Ultrasound-Imaging Application Pin Configuration TOP VIEW GND VGIN1+ VGIN1VREF VGIN2+ VGIN2GND GND VG_CLAMP_MODE GND GND 100 99 98 88 GND VCC 77 97 96 95 94 93 92 91 90 89 87 86 85 84 83 82 81 80 79 78 GND GND VGIN3VGIN3+ GND GND GND VGIN4VGIN4+ GND GND GND EXT_C1 EXT_C2 EXT_C3 VCC VGIN5VGIN5+ GND GND GND VGIN6VGIN6+ GND GND 76 GND GND GND VGOUT1VGOUT1+ GND GND GND GND GND GND VCC 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 75 74 73 72 71 70 69 68 67 66 65 64 63 62 61 60 59 58 57 56 55 54 53 52 51 VGOUT2VGOUT2+ GND VCC VGOUT3VGOUT3+ GND VGOUT4VGOUT4+ GND GND GND VG_CTL+ VG_CTLVGOUT5VGOUT5+ GND GND VGOUT6VGOUT6+ GND VCC VGOUT7VGOUT7+ GND MAX2037 26 27 28 30 32 33 34 35 44 29 31 36 37 38 39 40 41 42 43 45 46 47 48 49 VGIN7+ GND GND GND VGIN8VGIN8+ GND VGIN7- EXT_RES VCC TQFP ______________________________________________________________________________________ GND GND VGOUT8+ VGOUT8- GND GND GND VREF GND VCC GND GND GND VCC PD 50 11 Ultrasound Variable-Gain Amplifier MAX2037 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.) PACKAGE OUTLINE 100L TQFP, 14x14x1.0mm 21-0085 B 1 2 PACKAGE OUTLINE, 100L TQFP, 14x14x1.0mm 21-0085 B 2 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. 12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2006 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc. 100L,TQFP.EPS |
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