Shown in Figure 2-8, the ADS8900B used in Proposal 3 is a 20 bits SAR ADC with 1 MSPS in TI introduced in 2017, and since the ADS8900B does not have an internal reference, the REF70 is also required as an external reference. The proposal has the highest quality signal-to-noise ratio and dynamic range among the SAR ADC proposals. Designed for high-end ultrasound device CWD applications for higher image quality.

Figure 2-8 Proposal 3 ADS8900B and THS4551

Simulation of noise and amplitude frequency characteristics for Proposal 3.

Figure 2-9 Proposal 3 Simulated Circuit

Proposal 3 noise and amplitude frequency characteristics

Figure 2-10 Proposal-3 AC and Noise Performance

As shown from the simulation results of the Proposal 3, the Proposal 3 has the lowest total integral noise, highest signal-to-noise ratio and dynamic range among all of the SAR ADC proposals.