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19-0630; Rev 1; 2/09
Ultrasound Variable-Gain Amplifier
General Description
The MAX2035 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 dif-
ferential inputs and outputs and a total gain range of
typically 50dB. In addition, the VGAs offer very low out-
put-referred noise performance suitable for interfacing
with 10-bit ADCs.
The MAX2035 VGA is optimized for less than ±0.5dB
absolute gain error to ensure minimal channel-to-chan-
nel ultrasound beamforming focus error. The device’s
differential outputs are designed to directly drive ultra-
sound ADCs through an external passive anti-aliasing
filter. A switchable clamp is also provided at each ampli-
fier’s outputs to limit the output signals, thereby prevent-
ing 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 -62dBc 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 MAX2035 operates from a +5.0V power supply,
consuming only 127mW/channel. The device is avail-
able in a 100-pin TQFP package with an exposed pad.
Electrical performance is guaranteed over a 0°C to
+70°C temperature range.
Applications
Ultrasound Imaging
Sonar
Features
8-Channel Configuration
High Integration for Ultrasound Imaging
Applications
Pin Compatible with the MAX2036 Ultrasound
VGA Plus CW Doppler Beamformer
Maximum Gain, Gain Range, and Output-Referred
Noise Optimized for Interfacing with 10-Bit ADCs
Maximum Gain of 39.5dB
Total Gain Range of 50dB
60nV/Hz Ultra-Low Output-Referred Noise at
5MHz
Pin-for-Pin 12-Bit Compatibility Supported By
MAX2037/MAX2038
±0.5dB Absolute Gain Error
Switchable Output VGA Clamp Eliminating ADC
Overdrive
Fully Differential VGA Outputs for Direct ADC
Drive
Variable Gain Range Achieves 50dB Dynamic
Range
-62dBc HD2 at VOUT = 1.5VP-P and fIN = 5MHz
Two-Tone Ultrasound-Specific* IMD3 of -52dBc at
VOUT = 1.5VP-P and fIN = 5MHz
127mW Consumption per Channel
*See the Ultrasound-Specific IMD3 Specification in the
Applications Information section.
Functional Diagram
VCC VREF
VG_CTL+
VG_CTL-
VGIN1+
VGIN1-
VGIN8+
VGIN8-
PD
MAX2035
-10.5dB TO +39.5dB
VGA 50Ω
VGA
••
••
••
50Ω
50Ω
50Ω
BIAS
CIRCUITRY
VG_CLAMP_MODE
VGOUT1+
VGOUT1-
VGOUT8+
VGOUT8-
GND EXT_RES
Ordering Information
PART
TEMP RANGE PIN-PACKAGE
MAX2035CCQ-D
0°C to +70°C 100 TQFP-EP
MAX2035CCQ-TD
0°C to +70°C 100 TQFP-EP
MAX2035CCQ+D
0°C to +70°C 100 TQFP-EP
MAX2035CCQ+TD
0°C to +70°C 100 TQFP-EP
EP = Exposed pad.
+Denotes a lead(Pb)-free/RoHS-compliant package.
-Denotes a package containing lead(Pb).
T = Tape and reel.
D = Dry packing.
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.

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Ultrasound Variable-Gain Amplifier
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 = +70°C)
100-Pin TQFP
(derated 45.5mW/°C above +70°C).........................3636.4mW
Operating Temperature Range...............................0°C to +70°C
Junction Temperature ......................................................+150°C
θJC (Note 1) .....................................................................+2°C/W
θJA (Note 1) ...................................................................+22°C/W
Storage Temperature Range .............................-40°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-
layer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.
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, VCM = (3/5)VREF, VGND = 0, 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 = 1kΩ, TA = 0°C to +70°C. Typical
values are at VCC = VREF = 5V, TA = +25°C, unless otherwise noted.) (Note 2)
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
SYMBOL
VCC
CONDTIONS
VREF (Note 3)
IVCC
IREF
Refers to VCC supply
current plus VREF current
PD = 0
PD = 1
Refers to VCC supply current
Minimum gain
Maximum gain
VCM
VIH
VIL
MIN TYP MAX UNITS
4.75 5 5.25
V
4.75 5 5.25
V
204 231
27 33
192 216
12 15
mA
mA
mA
24 27 mA
+2
-2 VP-P
2.85 3.0 3.15
V
4.5 5
mA
2.3 V
0.8 V
2 _______________________________________________________________________________________

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Ultrasound Variable-Gain Amplifier
AC ELECTRICAL CHARACTERISTICS
(Figure 2, VCC = VREF = 4.75V to 5.25V, VCM = (3/5)VREF, VGND = 0, 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 = 1kΩ, TA = 0°C to +70°C. Typical
values are at VCC = VREF = 5V, TA = +25°C, unless otherwise noted.) (Note 2)
PARAMETER
Large-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
Output-Referred Noise
Second Harmonic
Third-Order Intermodulation
Distortion
SYMBOL
f-3dB
RIN
CIN
ROUT
CONDITIONS
VOUT = 1.5VP-P,
3dB bandwidth,
gain = 20dB
Differential output
capacitance is 10pF,
capacitance to GND at
each single-ended
output is 60pF, RL = 1kΩ
No capacitive load,
RL = 1kΩ
fRF = 10MHz, each input to ground
MIN
170
HD2
IMD3
TA = +25°C, -2.0V < VG_CTL < -1.8V, VREF = 5V
TA = +25°C, -1.8V < VG_CTL < +1.2V, VREF = 5V
TA = +25°C, +1.2V < VG_CTL < +2.0V, VREF = 5V
50dB gain change to within 1dB final value
VG_CTL set for maximum gain,
no input signal
VG_CTL set for
+20dB of gain
No input signal
VOUT = 1.5VP-P,
1kHz offset
VG_CLAMP_MODE = 1,
VG_CTL set for +20dB of gain,
fRF = 5MHz, VOUT = 1.5VP-P
VG_CLAMP_MODE = 1,
VG_CTL set for +20dB of gain,
fRF = 10MHz, VOUT = 1.5VP-P
VG_CLT set for +20dB of gain,
fRF1 = 5MHz, fRF2 = 5.01MHz,
VOUT = 1.5VP-P, VREF = 5V (Note 4)
-55
-40
TYP MAX UNITS
17
MHz
22
200
15
100
39.5
-10.5
50
±0.6
±0.5
±1.2
1
2
60
120
230 Ω
pF
Ω
dB
dB
dB
dB
µs
nV/Hz
nV/Hz
-62
dBc
-62
-52 dBc
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Ultrasound Variable-Gain Amplifier
AC ELECTRICAL CHARACTERISTICS (continued)
(Figure 2, VCC = VREF = 4.75V to 5.25V, VCM = (3/5)VREF, VGND = 0, 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 = 1kΩ, TA = 0°C to +70°C. Typical
values are at VCC = VREF = 5V, TA = +25°C, unless otherwise noted.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN TYP MAX UNITS
Channel-to-Channel Crosstalk
VOUT = 1VP-P differential, fRF = 10MHz,
VG_CTL set for +20dB of gain
-80 dB
Maximum Output Voltage at
Clamp ON
Maximum Output Voltage at
Clamp OFF
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
2.2
VP-P
differential
3.4
VP-P
differential
Note 2: Specifications at TA = +25°C and TA = +70°C are guaranteed by production test. Specifications at TA = 0°C are guaranteed
by design and characterization.
Note 3: 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 4: See the Ultrasound-Specific IMD3 Specification section.
Typical Operating Characteristics
(Figure 2, VCC = VREF = 4.75V to 5.25V, VGND = 0, 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 = 1kΩ, TA = 0°C to +70°C. Typical val-
ues are at VCC = VREF = 5V, VCM = 3.0V, TA = +25°C, unless otherwise noted.)
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
0
OVERDRIVE PHASE DELAY
vs. FREQUENCY
VIN1 = 35mVP-P DIFFERENTIAL
VIN2 = 87.5mVP-P DIFFERENTIAL
GAIN = 20dB
2.5 5.0 7.5 10.0 12.5 15.0 17.5 20.0
FREQUENCY (MHz)
POWER-SUPPLY MODULATION RATIO
-30
VOUT = 1.5VP-P DIFFERENTIAL
-40
VMOD = 50mVP-P, fCARRIER = 5MHz,
GAIN = 20dB
-50
-60
-70
-80
-90
0
25 50 75 100 125 150 175 200
FREQUENCY (kHz)
TWO-TONE ULTRASOUND-SPECIFIC
IMD3 vs. GAIN
0
VOUT = 1VP-P DIFFERENTIAL
-10 GAIN = 20dB
-20
-30
f = 10MHz
-40
-50
-60
f = 2MHz, 5MHz
-70
-80
-15 -5
5 15 25 35 45
GAIN (dB)
4 _______________________________________________________________________________________

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Ultrasound Variable-Gain Amplifier
Typical Operating Characteristics (continued)
(Figure 2, VCC = VREF = 4.75V to 5.25V, VGND = 0, 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 = 1kΩ, TA = 0°C to +70°C. Typical val-
ues are at VCC = VREF = 5V, VCM = 3.0V, TA = +25°C, unless otherwise noted.)
SECOND-HARMONIC DISTORTION
vs. GAIN
0
-10 VOUT = 1VP-P DIFFERENTIAL
-20
-30
-40 f = 12MHz
-50 f = 5MHz
-60
-70
-80 f = 2MHz
-90
-100
-15 -5 5 15 25 35 45
GAIN (dB)
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
-15
THIRD-HARMONIC DISTORTION
vs. GAIN
VOUT = 1VP-P DIFFERENTIAL
f = 12MHz
f = 5MHz
f = 2MHz
-5 5 15 25 35
GAIN (dB)
45
OVERLOAD RECOVERY TIME
MAX2035 toc06
f = 5MHz DIFFERENTIAL
INPUT
200mV/div
OVERLOAD RECOVERY TIME
MAX2035 toc07
f = 5MHz DIFFERENTIAL
INPUT
200mV/div
DIFFERENTIAL
OUTPUT
500mV/div
DIFFERENTIAL
OUTPUT
500mV/div
OUTPUT OVERLOAD TO 1VP-P
OUTPUT OVERLOAD TO 100mVP-P
CHANNEL-TO-CHANNEL CROSSTALK
vs. GAIN
-60
VOUT = 1.5VP-P DIFFERENTIAL
-65 f = 10MHz, ADJACENT CHANNELS
-70
-75
CHANNEL-TO-CHANNEL CROSSTALK
vs. FREQUENCY
-30
VOUT = 1VP-P DIFFERENTIAL
-40 GAIN = 20dB, ADJACENT CHANNELS
-50
-60
-80 -70
-85 -80
-90 -90
-95 -100
-100
-15 -5
5 15 25 35 45
GAIN (dB)
-110
1
10
FREQUENCY (MHz)
100
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