Adc Noise Floor Calculation

In this case the noise floor of the fft would be equal to the noise spectral density of the adc but the total noise power still has never changed.

Adc noise floor calculation.

The same noise power is only spread across finer frequency bin widths as seen in figure 1. For small analog input signals on the order of 35dbfs the thermal quantization noise power dominate the adc noise floor which is used to approximate the adc s effective noise figure nf. Once the adc s nf is known the cascaded noise figure equation can be used to determine the overall receiver noise figure at the receiver input terminal. This application report gives a method to calculate the effective noise figure of the whole signal chain and how knowing this helps correlate it with effective noise floor and dynamic range calculations for the last element the analog to digital converter adc in the receiver chain.

Measure the snr of the adc in nyquist bandwidth usually 0 5db or 1db below fullscale normalize the converter s noise power to a 1hz bandwidth by simply subtracting 10log fs 2 from the snr value. Calculate the input noise of the converter which is the theoretical thermal noise floor limit ktb 174dbm at room temperature. Adisimadc the fft output can be used like an analog spectrum analyzer to measure the amplitude of the.