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Micropower Op Amp Drives 8-Channel 18-Bit Simultaneous Sampling ADC without Compromising Accuracy or Breaking the Power Budget

Design Note 541 details a low-power buffer circuit for the LTC2348-18 18-bit SAR ADC using the LT6020 precision op amp to maintain high accuracy at low sampling rates.

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Overview

This design document describes a micropower driver circuit for the LTC2348-18, an 8-channel simultaneous sampling 18-bit SAR ADC. The design utilizes the LT6020 dual precision op amp as a non-inverting buffer to drive the ADC inputs while significantly reducing the power budget. At a 10ksps sampling rate, the system achieves 95.8dB SNR and -108dB THD with a combined offset of less than 1LSB. The document provides technical analysis on RC filter selection to minimize noise and sampling transients, alongside performance curves for SNR, THD, and offset across various frequencies.

Use Cases

  • 8-channel simultaneous data acquisition systems
  • Low-power precision instrumentation
  • Battery-powered sensor monitoring
  • DC and low-frequency signal measurement

Topics

LTC2348-18
LT6020
SAR ADC
18-bit ADC
simultaneous sampling
micropower op amp
precision buffer
Analog Devices
Linear Technology
Design Note 541

Referenced Parts

LT6020

Linear Technology

The LT6020 is a dual micropower, 5V/μs precision rail-to-rail output op amp with input offset voltage of less than 30μV (maximum)... For all eight channels this adds up to only 24mW.

LTC2348-18

Linear Technology

The LTC2348-18 is a low noise, 8-channel simultaneous sampling 18-bit successive approximation register (SAR) ADC with wide input common mode range.

LTC2348-18.

Maxim

inputs of the LTC2348-18. Maximum power dissipation

Micropower Op Amp Drives 8-Channel 18-Bit Simultaneous Sampling ADC without Compromising Accuracy or Breaking the Power Budget | Design Resources