SLOS358C September 2011 – April 2020 THS4531
To show achievable performance with a high performance SAR ADC, the THS4531 is tested as the drive amplifier for the ADS8321. The ADS8321 is a 16-bit, SAR ADC that offers excellent AC and DC performance, with ultra-low power and small size. The circuit shown in Figure 88 is used to test the performance. Data was taken using the ADS8321 at 100 kSPS with input frequency of 10 kHz and signal levels 0.5 dB below full scale. The FFT plot of the spectral performance is in Figure 89. A summary of the FFT analysis results are in Table 6 along with ADS8321 typical data sheet performance at fS = 100 kSPS. Please refer to its data sheet for more information.
The standard ADS8321 EVM and THS4531 EVM are modified to implement the schematic in Figure 88 and used to test the performance of the THS4531 as a drive amplifier. With single supply +5 V supply the output common-mode of the THS4531 defaults to +2.5 V as required at the input of the ADS8321 so the VOCM input of the THS4531 simply bypassed to GND with 0.22 µF capacitor. The summary of results of the FFT analysis versus typical data sheet performance shown in Table 6 show the THS4531 will make an excellent drive amplifier for this ADC.
|THS4531 + ADS8321||10 kHz||-0.5 dBFS||87 dBc||-96 dBc||87 dBc||100 dBc|
|ADS8321 data sheet (typical)||10 kHz||-0.5 dBFS||87 dBc||-86 dBc||84 dBc||86 dBc|