Quad-Channel 250-Msps Digitizer with Variable Gain Amplifier Reference Design


Design files


This reference design shows a quad channel, 14-bit, 250-Msps digitizer with wide input range using the LMH6881 programmable differential amplifier and ADS4449 quad-channel, 14-bit, 250-Msps ADC. This combination allows an input voltage range of approximately 1 Vpp to 100 uVpp (4 dBm to -75 dBm) while maintaining a minimum SNR of 6 dB. Performance versus input frequency is shown for both AC and DC coupled applications. Various options for common-mode voltages, power supplies, and interfaces are discussed and measured to meet the requirements of a variety of applications. Anti-aliasing filter examples are shown along with the performance improvements that they provide.

  • Gain range of 6-dB to 26-dB allows wide input voltage range of 100 uVpp to 1 Vpp
  • Allows single-ended or differential input source
  • SFDR > 77 dBFs, SNR > 71 dBFS
  • Examples of both AC and DC coupled interfaces
  • Demonstrates anti-aliasing filter design and performance gains
  • Common mode voltage considerations for best performance are discussed
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A fully assembled board has been developed for testing and performance validation only, and is not available for sale.

Design files & products

Design files

Download ready-to-use system files to speed your design process.

TIDU174.PDF (542 K)

Reference design overview and verified performance test data

TIDCA30.ZIP (1595 K)

Detailed schematic diagram for design layout and components


Detailed schematic diagram for design layout and components


Complete listing of design components, reference designators, and manufacturers/part numbers


Includes TI products in the design and potential alternatives.

AC/DC & DC/DC converters (integrated FET)

TPS62420Dual, Adjustable, 600mA and 1000mA, 2.25MHz Step-Down Converter with 1-Wire Interface in QFN

Data sheet: PDF | HTML
High-speed ADCs (≥10 MSPS)

ADS4449Quad-Channel, 14-Bit, 250-MSPS Analog-to-Digital Converter (ADC)

Data sheet: PDF | HTML
Linear & low-dropout (LDO) regulators

TPS7A801-A, high-PSRR, ultra-low-dropout voltage regulator with low-IQ & enable

Data sheet: PDF | HTML

LMH68812.4GHz Programmable Differential Amplifier with Gain Control

Data sheet: PDF | HTML

LMH68822.4 GHz Dual Programmable Differential Amplifier with Gain Control

Data sheet: PDF | HTML
eFuses & hot swap controllers

TPS24005.5-V over voltage protection controller with 100-V input transient protection

Data sheet: PDF | HTML

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Design tools & simulation

Simulation model

TIDA-00094 TINA Simulation — TIDCA31.ZIP (210 K)

Technical documentation

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Type Title Date
Design guide Quad-Channel 250-Msps Digitizer With Variable Gain Amplifier Design Guide Mar. 30, 2014

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