SBAS774B May 2016 – December 2021 ADC32RF80 , ADC32RF83
PRODUCTION DATA
The signal-to-noise ratio (SNR) of the ADC is limited by three different factors: quantization noise, thermal noise, and jitter, as shown in Equation 5. The quantization noise is typically not noticeable in pipeline converters and is 84 dB for a 14-bit ADC. The thermal noise limits the SNR at low input frequencies and the clock jitter sets the SNR for higher input frequencies.
The SNR limitation resulting from sample clock jitter can be calculated by Equation 6:
The total clock jitter (TJitter) has two components: the internal aperture jitter (90 fS) is set by the noise of the clock input buffer and the external clock jitter. TJitter can be calculated by Equation 7:
External clock jitter can be minimized by using high-quality clock sources and jitter cleaners as well as band-pass filters at the clock input. A faster clock slew rate also improves the ADC aperture jitter.
The ADC32RF8x has a thermal noise of approximately 63 dBFS and an internal aperture jitter of 90 fS. The SNR, depending on the amount of external jitter for different input frequencies, is shown in Figure 9-2.