Quad-Channel 250-Msps Digitizer with Variable Gain Amplifier Reference Design
TIDA-00094
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Description
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.
Features
- 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
See the Important Notice and Disclaimer covering reference designs and other TI resources.