19-3969; Rev 1; 3/07 Quad-Channel, Ultra-Low-Noise Amplifier with Digitally Programmable Input Impedance *See the Ultrasound-Specific IMD3 Specification in the Applications Information section. GND GND VCC OUT3- OUT3+ VCC OUT2- OUT2+ GND OUT1- VCC OUT1+ OUT4- GND 39 22 GND GND 40 21 GND VCC 41 20 VCC D2 42 19 D0 PD 43 18 D1 VCC 44 17 VCC VCC 45 16 VCC GND 46 15 GND ZF1 47 14 INB4 IN1 48 13 INC4 MAX2034 1 2 3 4 5 6 7 8 9 10 11 12 IN4 **EP = Exposed paddle. +Denotes lead-free package. T = Tape-and-reel package. 23 ZF4 48 Thin QFN-EP** T4877-4 (7mm x 7mm) 24 38 INB3 48 Thin QFN-EP** T4877-4 (7mm x 7mm) 37 VCC INC3 MAX2034CTM-T 0°C to +70°C 48 Thin QFN-EP** T4877-4 (7mm x 7mm) OUT4+ GND IN3 MAX2034CTM+T 0°C to +70°C 48 Thin QFN-EP** T4877-4 (7mm x 7mm) 36 35 34 33 32 31 30 29 28 27 26 25 ZF3 0°C to +70°C PKG CODE TOP VIEW INB2 MAX2034CTM 0°C to +70°C PINPACKAGE Pin Configuration IN2 MAX2034CTM+ TEMP RANGE Sonar Signal Amplification INC2 PART Ultrasound Imaging ZF2 Ordering Information Applications INB1 The MAX2034 has excellent dynamic and linearity performance characteristics optimized for all ultrasoundimaging modalities including second harmonic 2D imaging and continuous wave Doppler. The device achieves a second harmonic distortion of -68dBc at VOUT = 1VP-P and fIN = 5MHz, and an ultrasound-specific* two-tone third-order intermodulation distortion performance of -55dBc at VOUT = 1VP-P and fIN = 5MHz. The MAX2034 is also optimized for quick overload recovery for operation under the large input signal conditions typically found in ultrasound input-buffer imaging applications. The MAX2034 is available in a 48-pin thin QFN package with an exposed paddle. Electrical performance is guaranteed over a 0°C to +70°C temperature range. ♦ High-Level Integration of 4 Channels ♦ Digitally Programmable Input Impedance (RIN) of 50Ω, 100Ω, 200Ω, and 1kΩ ♦ Integrated Input Clamp ♦ Integrated Input-Damping Capacitor ♦ Ultra-Low 2.2dB Noise Figure at RS = RIN = 200Ω ♦ 70MHz, -3dB Bandwidth ♦ Low 58mW/Channel Power Dissipation ♦ HD2 of -68dBc at VOUT = 1VP-P and fIN = 5MHz for Exceptional Second Harmonic Imaging Performance ♦ Two-Tone Ultrasound-Specific* IMD3 of -55dBc at VOUT = 1VP-P and fIN = 5MHz for Exceptional PW/CW Doppler Performance ♦ Quick Large-Signal Overload Recovery ♦ Single +5V Supply Operation ♦ Sleep Mode INC1 The MAX2034 four-channel, low-power, ultra-low-noise preamplifier is designed for ultrasound and medical instrumentation applications. Each low-noise amplifier has a single-ended input, differential output, a highly accurate 19dB fixed gain, and a wide -3dB bandwidth of 70MHz. The high-gain accuracy of the amplifier allows for exceptional channel-to-channel gain matching, which is necessary for high-performance ultrasound-imaging applications. The MAX2034 also includes an on-chip programmable input impedance feature that allows the device to be compatible with a variety of common source impedances ranging from 50Ω to 1kΩ. The input impedance of each amplifier uses a feedback topology for active impedance matching. The active input impedance matching feature achieves an exceptionally low 2.2dB noise figure with a source and input impedance of 200Ω. Features THIN QFN Typical Application Circuit appears at end of data sheet. ________________________________________________________________ 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 MAX2034 General Description MAX2034 Quad-Channel, Ultra-Low-Noise Amplifier with Digitally Programmable Input Impedance ABSOLUTE MAXIMUM RATINGS VCC to GND ...........................................................-0.3V to +5.5V Any Other Pins to GND...............................-0.3V to (VCC + 0.3V) IN_ to INB_ ..................................................................-2V to +2V INC_ to GND .....................................................-24mA to +24mA Continuous Power Dissipation (TA = +70°C) 48-Pin TQFN (derated 40mW/°C above +70°C) ........3200mW Operating Temperature Range...............................0°C to +70°C Junction Temperature ......................................................+150°C θJC ...................................................................................0.8°C/W θJA ....................................................................................25°C/W Storage Temperature Range .............................-40°C to +150°C Lead Temperature (soldering, 10s) .................................+300°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. DC ELECTRICAL CHARACTERISTICS (MAX2034 Typical Application Circuit, VCC = +4.75V to +5.25V, no input signal applied between IN1–IN4 and GND, TA = 0°C to +70°C. Typical values are at VCC = +5.0V and TA = +25°C, unless otherwise noted.) (Note 1) PARAMETER Supply Voltage Total Supply Current SYMBOL CONDITIONS MIN TYP MAX UNITS 4.75 5.0 5.25 V ICC Normal mode (PD = 0), no signals applied, see the Typical Operating Characteristics for ICC as a function of input signal 46.5 54.5 ICC,PD Sleep mode (PD = 1), VIN_ = 112mVP-P at 5MHz 0.8 4 VCC mA LOGIC INPUTS (PD, D2, D1, D0) Input High Voltage VIH Input Low Voltage VIL 4.0 1.0 V V Input Current with Logic-High IIH 1 µA Input Current with Logic-Low IIL 1 µA AC ELECTRICAL CHARACTERISTICS (MAX2034 Typical Application Circuit, VCC = +4.75V to +5.25V, source impedance RS = 200Ω, PD = 0, D2/D1/D0 = 0/1/0 (RIN = 200Ω), signal AC-coupled to IN_, INB_ is AC grounded, VOUT is the differential output between OUT_+ and OUT_-, fIN_ = 5MHz, RL = 200Ω between the differential outputs, CL = 20pF from each output to ground, TA = 0°C to +70°C. Typical values are at VCC = 5.0V and TA = +25°C, unless otherwise noted.) (Note 1) PARAMETER Input Resistance SYMBOL RIN CONDITIONS MIN D2/D1/D0 = 0/0/0 53 D2/D1/D0 = 0/0/1 105 D2/D1/D0 = 0/1/0 206 D2/D1/D0 = 0/1/1 870 Typical Input Resistance Variation from Nominal Programmed CIN Gain AV Part-to-Part Gain Variation from Nominal Slew Rate 2 MAX (OUT_+ - OUT_-) / IN_ TA = +25oC, RL = 200Ω ±10% f-3dB D2/D1/D0 = 0/0/0, (50Ω input impedance), VOUT = 0.2VP-P 0 UNITS Ω ±1 Input Capacitance -3dB Small-Signal Gain Bandwidth TYP % 40 pF 19 dB ±0.1 ±0.5 dB 70 MHz 280 V/µs _______________________________________________________________________________________ Quad-Channel, Ultra-Low-Noise Amplifier with Digitally Programmable Input Impedance (MAX2034 Typical Application Circuit, VCC = +4.75V to +5.25V, source impedance RS = 200Ω, PD = 0, D2/D1/D0 = 0/1/0 (RIN = 200Ω), signal AC-coupled to IN_, INB_ is AC grounded, VOUT is the differential output between OUT_+ and OUT_-, fIN_ = 5MHz, RL = 200Ω between the differential outputs, CL = 20pF from each output to ground, TA = 0°C to +70°C. Typical values are at VCC = 5.0V and TA = +25°C, unless otherwise noted.) (Note 1) PARAMETER Noise Figure SYMBOL NF CONDITIONS MIN TYP RS = RIN = 50Ω 4.1 RS = RIN = 100Ω 2.9 RS = RIN = 200Ω 2.2 MAX UNITS dB RS = RIN = 1000Ω 1.4 Input-Referred Noise Voltage D2 = 1 (high input impedance), fIN_ = 5MHz 0.87 nV/√Hz Input-Referred Noise Current D2 = 1 (high input impedance), fIN_ = 5MHz 2.1 pA/√Hz Second Harmonic HD2 Third Harmonic HD3 Two-Tone Intermodulation Distortion (Note 2) fIN_ = 5MHz, VOUT = 1VP-P differential -50 -68 fIN_ = 10MHz, VOUT = 1VP-P differential -66 fIN_ = 5MHz, VOUT = 1VP-P differential -50 fIN_ = 10MHz, VOUT = 1VP-P differential -44 4.99MHz tone relative to the second tone at 5.01MHz, which is 25dB lower than the first tone at 5.00MHz, VOUT = 1VP-P differential -45 dBc dBc -55 dBc IMD3 7.49MHz tone relative to the second tone at 7.51MHz, which is 25dB lower than the first tone at 7.50MHz, VOUT = 1VP-P differential -52 Maximum Output Signal Amplitude Differential output 4.4 Gain Compression Gain at VIN_ = 112mVP-P relative to gain at VIN_ = 550mVP-P 0.5 Output Common-Mode Level VP-P 3 dB 2.45 V 5.3 Ω ±1.5 deg 66 dB Supply current settles to 90% of nominal sleepmode current ICC,PD 0.3 ms VOUT settles to 90% of final 1VP-P output 0.3 ms Output Impedance Single-ended Phase Matching Between Channels Phase difference between channels with VIN_ = 195mV peak (-3dB full scale), fIN_ = 10MHz Channel-to-Channel Crosstalk fIN_ = 10MHz, VOUT = 1VP-P, adjacent channels Switch Time from Normal to Sleep Mode Switch Time from Sleep to Normal Mode 50 Note 1: Min and max limits at TA = +25°C and +70°C are guaranteed by design, characterization, and/or production test. Note 2: See the Ultrasound-Specific IMD3 Specification in the Applications Information section. _______________________________________________________________________________________ 3 MAX2034 AC ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (MAX2034 Typical Application Circuit, VCC = +4.75V to +5.25V, source impedance RS = 200Ω, PD = 0, D2/D1/D0 = 0/1/0 (RIN = 200Ω), signal AC-coupled to IN_, INB_ is AC grounded, VOUT is the differential output between OUT_+ and OUT_-, fIN_ = 5MHz, RL = 200Ω between the differential outputs, CL = 20pF from each output to ground, TA = 0°C to +70°C, unless otherwise specified.) SMALL-SIGNAL BANDWIDTH vs. FREQUENCY 15 GAIN (dB) GAIN (dB) 10 10 5 5 5 0 0 0 -5 -5 0.1 1 10 100 1 10 100 1000 0.1 10 100 1000 FREQUENCY (MHz) LARGE-SIGNAL BANDWIDTH vs. FREQUENCY COMPLEX INPUT IMPEDANCE MAGNITUDE vs. FREQUENCY COMPLEX INPUT IMPEDANCE MAGNITUDE vs. FREQUENCY 0 120 55 110 45 90 40 80 35 70 60 30 -5 0.1 1 10 100 100 1000 0 10 FREQUENCY (MHz) 20 30 40 0 50 5 COMPLEX INPUT IMPEDANCE MAGNITUDE vs. FREQUENCY COMPLEX INPUT IMPEDANCE MAGNITUDE vs. FREQUENCY 1150 MAX2034 toc07 D2/D1/D0 = 0/1/0 RIN = 200Ω D2/D1/D0 = 0/1/1 RIN = 1kΩ 1000 850 IZINI 225 200 15 20 25 30 HARMONIC DISTORTION vs. FREQUENCY -20 HARMONIC DISTORTION (dBc) 275 10 FREQUENCY (MHz) FREQUENCY (MHz) 700 550 175 400 150 250 VOUT = 1VP-P DIFFERENTIAL RL = 200Ω -30 -40 THIRD HARMONIC -50 -60 -70 125 MAX2034 toc09 5 60 50 D2/D1/D0 = 0/0/1 RIN = 100Ω 130 IZINI IZINI 15 10 D2/D1/D0 = 0/0/0 RIN = 50Ω 65 140 MAX2034 toc05 MAX2034 toc04 70 MAX2034 toc06 FREQUENCY (MHz) VIN = 500mVP-P RIN = 50Ω 250 1 FREQUENCY (MHz) 25 20 -5 0.1 1000 MAX2034 toc08 GAIN (dB) 10 VIN_ = 500mVP-P, RIN = 200Ω 20 15 15 GAIN (dB) VIN = 112mVP-P RIN = 50Ω 20 25 MAX2034 toc02 VIN_ = 112mVP-P, RIN = 200Ω 20 25 MAX2034 toc01 25 LARGE-SIGNAL BANDWIDTH vs. FREQUENCY MAX2034 toc03 SMALL-SIGNAL BANDWIDTH vs. FREQUENCY IZINI MAX2034 Quad-Channel, Ultra-Low-Noise Amplifier with Digitally Programmable Input Impedance SECOND HARMONIC 100 100 0 0 4 8 12 FREQUENCY (MHz) 4 16 20 4 8 12 FREQUENCY (MHz) 16 20 -80 0 5 10 15 20 FREQUENCY (MHz) _______________________________________________________________________________________ 25 30 Quad-Channel, Ultra-Low-Noise Amplifier with Digitally Programmable Input Impedance -10 -30 -40 -50 -60 -70 5 10 15 20 25 3 VIN = 200mVP-P 2 VIN = 112mVP-P 1 SMALL-SIGNAL NOISE FIGURE 0.1 1 10 100 FREQUENCY (MHz) OFFSET FREQUENCY (kHz) GAIN-ERROR HISTOGRAM CHANNEL-TO-CHANNEL CROSSTALK vs. FREQUENCY SAMPLE SIZE = 243 UNITS fIN_ = 5MHz, VIN = 112mVP-P 40 -30 VOUT = 1VP-P DIFFERENTIAL RL = 200Ω ADJACENT CHANNELS -40 -50 CROSSTALK (dB) 35 % OF UNITS VIN = 300mVP-P 30 MAX2034 toc12 45 4 0 0 50 RIN = 200Ω RL = 200Ω fIN_ = 5MHz 5 MAX2034 toc13 IMD3 (dBc) -20 6 MAX2034 toc11 VOUT = 1VP-P DIFFERENTIAL RL = 200Ω LARGE-SIGNAL NOISE FIGURE vs. OFFSET FREQUENCY LARGE-SIGNAL NOISE FIGURE (dB) 0 MAX2034 toc10 TWO-TONE ULTRASOUND-SPECIFIC IMD3 vs. FREQUENCY 30 25 20 15 -60 -70 -80 10 -90 5 -100 1 0.18 0.14 0.10 0.06 0.02 -0.04 -0.08 -0.12 -0.16 -0.20 0 10 100 FREQUENCY (MHz) GAIN ERROR (dB) SUPPLY CURRENT vs. DIFFERENTIAL OUTPUT VOLTAGE MAX2034 toc14 ALL CHANNELS ACTIVE 110 SUPPLY CURRENT (mA) LARGE-SIGNAL RECOVERY MAX2034 toc15 130 fIN_ = 5MHz INPUT IN_ 500mV/div 90 RL = 200Ω DIFFERENTIAL OUTPUT OUT_+ - OUT_2.0V/div 70 NO LOAD 50 30 0 1 2 3 4 400ns/div DIFFERENTIAL OUTPUT VOLTAGE (VP-P) _______________________________________________________________________________________ 5 MAX2034 Typical Operating Characteristics (continued) (MAX2034 Typical Application Circuit, VCC = +4.75V to +5.25V, source impedance RS = 200Ω, PD = 0, D2/D1/D0 = 0/1/0 (RIN = 200Ω), signal AC-coupled to IN_, INB_ is AC grounded, VOUT is the differential output between OUT_+ and OUT_-, fIN_ = 5MHz, RL = 200Ω between the differential outputs, CL = 20pF from each output to ground, TA = 0°C to +70°C, unless otherwise specified.) MAX2034 Quad-Channel, Ultra-Low-Noise Amplifier with Digitally Programmable Input Impedance Typical Operating Characteristics (continued) (MAX2034 Typical Application Circuit, VCC = +4.75V to +5.25V, source impedance RS = 200Ω, PD = 0, D2/D1/D0 = 0/1/0 (RIN = 200Ω), signal AC-coupled to IN_, INB_ is AC grounded, VOUT is the differential output between OUT_+ and OUT_-, fIN_ = 5MHz, RL = 200Ω between the differential outputs, CL = 20pF from each output to ground, TA = 0°C to +70°C, unless otherwise specified.) CLAMP SYMMETRY UNDER TRANSMIT RECOVERY LARGE-SIGNAL RECOVERY MAX2034 toc17 MAX2034 toc16 fIN_ = 5MHz fIN_ = 10MHz INPUT IN_ 500mV/div SINGLE-ENDED OUTPUT OUT_+ 1V/div DIFFERENTIAL OUTPUT OUT_+ - OUT_2.0V/div SINGLE-ENDED OUTPUT OUT_1V/div 200ns/div 400ns/div Pin Description PIN NAME 1 INC1 2 INB1 Channel 1 Analog Bypass Input. Connect a capacitor to GND as close as possible to the pin. 3 ZF2 Channel 2 Active Impedance-Matching Port. AC-couple to the source circuit with a capacitor. 4 IN2 Channel 2 LNA Analog Input. Single-ended input for channel 2 amplifier. Connect the analog input to the source circuit through a series capacitor. 5 INC2 Channel 2 Analog Input Clamp. Input port to the integrated clamping diodes. 6 INB2 Channel 2 Analog Bypass Input. Connect a capacitor to GND as close as possible to the pin. 7 ZF3 Channel 3 Active Impedance-Matching Port. AC-couple to the source circuit with a capacitor. 8 IN3 Channel 3 LNA Analog Input. Single-ended input for channel 3 amplifier. Connect the analog input to the source circuit through a series capacitor. 9 INC3 Channel 3 Analog Input Clamp. Input port to the integrated clamping diodes. 10 INB3 Channel 3 Analog Bypass Input. Connect a capacitor to GND as close as possible to the pin. 11 ZF4 Channel 4 Active Impedance-Matching Port. AC-couple to the source circuit with a capacitor. 12 IN4 Channel 4 LNA Analog Input. Single-ended input for channel 4 amplifier. Connect the analog input to the source circuit through a series capacitor. 13 INC4 Channel 4 Analog Input Clamp. Input port to the integrated clamping diodes. 14 INB4 Channel 4 Analog Bypass Input. Connect a capacitor to GND as close as possible to the pin. 15, 21, 22, 25, 26, 33, 37, 39, 40, 46 GND Ground 16, 17, 20, 27, 30, 34, 38, 41, 44, 45 VCC 5V Power Supply. Supply for the four LNAs. Bypass each VCC supply with a 100nF capacitor as close as possible to the pin. 6 FUNCTION Channel 1 Analog Input Clamp. Input port to the integrated clamping diodes. _______________________________________________________________________________________ Quad-Channel, Ultra-Low-Noise Amplifier with Digitally Programmable Input Impedance PIN NAME 18, 19, 42 D1, D0, D2 FUNCTION Digitally Programmable Inputs. Programs the input impedance of each amplifier. See Table 1 on input impedance programming information. 23 OUT4- Channel 4 LNA Analog Inverting Output 24 OUT4+ Channel 4 LNA Analog Noninverting Output 28 OUT3- Channel 3 LNA Analog Inverting Output 29 OUT3+ Channel 3 LNA Analog Noninverting Output 31 OUT2- Channel 2 LNA Analog Inverting Output 32 OUT2+ Channel 2 LNA Analog Noninverting Output 35 OUT1- Channel 1 LNA Analog Inverting Output 36 OUT1+ Channel 1 LNA Analog Noninverting Output 43 PD Power-Down. Drive PD high to put the device in sleep mode. Drive PD low for normal mode. 47 ZF1 Channel 1 Active Impedance-Matching Port. AC-couple to the source circuit with a capacitor. 48 IN1 Channel 1 LNA Analog Input. Single-ended input for channel 1 amplifier. Connect the analog input to the source circuit through a series capacitor. EP GND Exposed Paddle. Solder the exposed paddle to the ground plane using multiple vias. Detailed Description The MAX2034 is a four-channel, ultra-low-noise preamplifier. Each amplifier features single-ended inputs, differential outputs, and provides an accurate fixed gain of 19dB with a wide -3dB bandwidth of 70MHz. The highgain accuracy of the amplifier allows for exceptional channel-to-channel gain matching, which is necessary for high-performance ultrasound-imaging applications. The device has an exceptionally low noise figure, making it ideal for use in ultrasound front-end designs. Noise figure is typically 2.2dB for a source impedance and programmed input impedance of 200Ω. The MAX2034 is optimized for excellent dynamic range and linearity performance characteristics, making it ideal for ultrasound-imaging modalities including second harmonic 2D imaging and continuous wave Doppler. The device achieves an HD2 of -68dBc at VOUT = 1VP-P and fIN_ = 5MHz, and an ultrasound-specific two-tone IMD3 performance of -55dBc at V OUT = 1VP-P and f IN_ = 5MHz. See the Ultrasound-Specific IMD3 Specification in the Applications Information section. amplifier, A, being defined with a differential output. For common input impedances, the internal digitally programmed impedances can be used (see Table 1). For other input impedances, program the impedance for external resistor operation, and then use an externally supplied resistor to set the input impedance according to the above formula. The gain and input impedance of the MAX2034 vs. frequency are shown in the Typical Operating Characteristics. Both gain and input impedance are well behaved, with no peaking characteristics. This allows the device to be used with a variety of input networks, with no requirement for series ferrite beads or shunt capacitors for stability control. Table 1. Digitally Programmable Input Impedance D2 D1 D0 0 0 0 RIN (Ω) 50 Active Impedance Matching 0 0 1 100 To provide exceptional noise-figure characteristics, the input impedance of each amplifier uses a feedback topology for active impedance matching. A feedback resistor of the value (1 + (A / 2)) x RS is added between the inverting output of the amplifier to the input. The input impedance is the feedback resistor, ZF, divided by 1 + (A / 2). The factor of two is due to the gain of the 0 1 0 200 0 1 1 1k 1 0 0 1 0 1 1 1 0 1 1 1 Defined by external resistor _______________________________________________________________________________________ 7 MAX2034 Pin Description (continued) MAX2034 Quad-Channel, Ultra-Low-Noise Amplifier with Digitally Programmable Input Impedance Functional Diagram D2/D1/D0 PD ZF1 IN1 OUT1- INC1 OUT1+ INB1 MAX2034 Digitally Programmable Input Impedance The MAX2034 features an on-chip digitally programmable input impedance, which makes the part compatible with a variety of source impedances ranging from 50Ω to 1kΩ. The input impedance can be programmed for 50Ω, 100Ω, 200Ω, or 1kΩ through the digital inputs D2, D1, and D0. See Table 1 for programming details. In addition to these fixed values, virtually any other input impedance can be supported by using an off-chip external feedback resistor, RF. To utilize this feature, set D2, D1, and D0 to any of the four external resistor-controlled states shown in Table 1. The value of the off-chip feedback resistor can be determined by using the following relationship: RF = (1 + (A / 2)) x RS where RS is the source impedance, and A is the gain of the amplifier (A = 9) defined with a differential output. Noise Figure ZF2 IN2 OUT2- INC2 OUT2+ INB2 The MAX2034 is designed to provide maximum input sensitivity with its exceptionally low noise figure. The input active devices are selected for very low equivalent input noise voltage and current, and they have been optimized for source impedances from 50Ω to 1000Ω. Additionally, the noise contribution of the matching resistor is effectively divided by 1 + (A / 2). Using this scheme, typical noise figure of the amplifier is approximately 2.2dB for RIN = RS = 200Ω. Table 2 illustrates the noise figure for other input impedances. Table 2. Noise Figure vs. Source and Input Impedances ZF3 Rs (Ω) IN3 OUT3- INC3 OUT3+ RIN (Ω) NF (dB) 50 50 4.1 100 100 2.9 200 200 2.2 1000 1000 1.4 INB3 Input Clamp ZF4 IN4 OUT4- INC4 OUT4+ INB4 8 The MAX2034 includes configurable integrated inputclamping diodes. The diodes are clamped to ground at ±275mV. The input-clamping diodes can be used to prevent large transmit signals from overdriving the inputs of the amplifiers. Overdriving the inputs could possibly place charge on the input-coupling capacitor, causing longer transmit overload recovery times. Input signals are AC-coupled to the single-ended inputs IN1–IN4, but are clamped with the INC1–INC4 inputs. See the Typical Application Circuit. If external clamping devices are preferred, simply leave INC1–INC4 unconnected. _______________________________________________________________________________________ Quad-Channel, Ultra-Low-Noise Amplifier with Digitally Programmable Input Impedance 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. Internal signal clipping is symmetrical. Input overloads can be prevented with the input-clamping diodes. See the Typical Operating Characteristics that illustrate the rapid recovery time from a transmitrelated overload. Sleep Mode The sleep mode function allows the MAX2034 to be configured in a low-power state when the amplifiers are not being used. In sleep mode, all amplifiers are powered down, the total supply current of the device reduces to 0.8mA, and the input impedance of each amplifier is set at high impedance. Drive the PD input high to activate sleep mode. For normal operation, drive the PD input low. The Typical Application Circuit illustrates these coupling capacitors. If a ground-referenced current-limiting stage precedes the MAX2034 inputs, its output can be connected to the integrated clamping diodes on pins INC1–INC4 to facilitate very rapid recovery from transient overloads associated with transmitter operation in ultrasound applications. Analog Output Coupling The differential outputs of the MAX2034 are capable of driving a differential load impedance of 200Ω or greater. The differential output has a common-mode bias of approximately 2.45V. AC-couple these differential outputs if the next stage has a different commonmode input range. Board Layout The pin configuration of the MAX2034 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 MAX2034’s thin QFNEP package provides a low thermal-resistance path to the die. It is important that the PC board on which the MAX2034 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 PC board, either directly or through an array of plated via holes. Applications Information Analog Input Coupling AC-couple to ground the analog bypass input by connecting a 0.1µF capacitor at the INB1–INB4 input to GND (0.1µF recommended). Since the amplifiers are designed with a differential input stage, bypassing the INB1–INB4 inputs configures the MAX2034 for singleended inputs at IN1–IN4. Connect the IN1–IN4 inputs to their source circuits through 0.1µF series capacitors. Connect the feedback ports ZF1–ZF4 to the source circuits through 0.018µF capacitors. (These capacitors will be 1/(5.5) as large as the input-coupling capacitors. This equalizes the highpass filter characteristic of both the input and feedback input ports, due to the feedback resistance related by a factor of 1/(5.5) to the input impedance.) Note that the active input circuitry of the MAX2034 is stable, and does not require external ferrite beads or shunt capacitors to achieve high-frequency stability. -25dB ULTRASOUND IMD3 F1 - (F2 - F1) F1 F2 F2 + (F2 - F1) Figure 1. Ultrasound IMD3 Measurement Technique _______________________________________________________________________________________ 9 MAX2034 Integrated Input Damping Capacitor At high frequencies, gain peaking can occur due to an active input termination becoming less effective when the gain rolls off. Although an external shunting capacitor can be used to mitigate this effect, different input impedance modes require different capacitor values. The MAX2034 integrates a damping capacitor for each of the four programmed input impedance modes. When the input impedance is programmed by applying the appropriate D2/D1/D0, an optimal capacitor value is also chosen for the particular input impedance mode, eliminating the need for external capacitors. MAX2034 Quad-Channel, Ultra-Low-Noise Amplifier with Digitally Programmable Input Impedance D2/D1/D0 PD +V ZF_ 18nF 100nF 100nF IN_ OUT_100nF INC_ OUT_+ ONE CHANNEL INB_ MAX2034 -V 100nF Figure 2. Typical Single-Channel Ultrasound Application Circuit 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, F1 represents reflections from tissue and F2 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. 10 ______________________________________________________________________________________ Quad-Channel, Ultra-Low-Noise Amplifier with Digitally Programmable Input Impedance +5V 100nF 100nF 48 47 46 45 44 42 41 39 GND GND 40 VCC GND D2 43 VCC VCC PD VCC GND IN1 18nF ZF1 100nF 37 38 INC1 RS = 200Ω INB3 ZF4 100nF 18nF 30 29 8 9 28 EXPOSED PADDLE 27 10 26 11 25 12 100nF OUT1- 100nF VCC GND 100nF OUT2+ 100nF OUT2- 100nF VCC OUT3+ 100nF OUT3- 100nF 100nF VCC GND 100nF GND 13 14 15 16 17 18 19 20 21 22 23 24 INC4 100nF IN4 MAX2034 7 100nF OUT4- INC3 31 OUT1+ OUT4+ 100nF IN3 6 GND 18nF 32 GND 100nF 5 D0 ZF3 33 VCC INB2 4 D1 RS = 200Ω 34 VCC INC2 3 VCC 100nF IN2 GND ZF2 18nF 35 2 INB4 INB1 100nF RS = 200Ω 36 1 RS = 200Ω 100nF 100nF +5V 100nF 100nF +5V ______________________________________________________________________________________ 11 MAX2034 Typical 200Ω Application Circuit 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.) E DETAIL A 32, 44, 48L QFN.EPS MAX2034 Quad-Channel, Ultra-Low-Noise Amplifier with Digitally Programmable Input Impedance (NE-1) X e E/2 k e D/2 CL (ND-1) X e D D2 D2/2 b L E2/2 DETAIL B e E2 CL L L1 CL k CL L L e A1 A2 e A PACKAGE OUTLINE 32, 44, 48, 56L THIN QFN, 7x7x0.8mm 21-0144 12 ______________________________________________________________________________________ E 1 2 Quad-Channel, Ultra-Low-Noise Amplifier with Digitally Programmable Input Impedance PACKAGE OUTLINE 32, 44, 48, 56L THIN QFN, 7x7x0.8mm 21-0144 E 2 2 Revision History Pages changed at Rev 1: 1, 3, 4, 11, 12 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. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 13 © 2007 Maxim Integrated Products Springer is a registered trademark of Maxim Integrated Products, Inc. MAX2034 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.)