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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 differential inputs and outputs and a total gain range of typically 50dB. In addition, the VGAs offer very low output-referred noise performance suitable for interfacing with 10-bit ADCs.

The MAX2035 VGA is optimized for less than ¡À0.5dB absolute gain error to ensure minimal channel-to-channel 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 amplifier¡¯s outputs to limit the output signals, thereby prevent ing ADC overdrive or saturation.

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/¡ÌHz Ultra-Low Output-Referred Noise at

?? 5MHz

?? Pin-for-Pin 12-Bit Compatibility Supported By

?? MAX2037/MAX2038

? ¡À0.5dB 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

Applications

?? Ultrasound Imaging Sonar