Noise-Shaping of Additive Dither in Analog-to-Digital Converters

An analog-to-digital converter circuit module utilizing dither to reduce multiplicative noise. A dither generation circuit generates a noise-shaped analog dither signal having lower amplitudes at frequencies below a cutoff frequency than at frequencies above the cutoff frequency. The noise-shaped analog dither signal is added to the input analog signal to be converted and the summed signal applied to an analog-to-digital converter The dither generation circuit may be implemented as an analog dither generator followed by an analog high-pass filter. The dither generation circuit may alternatively be implemented digitally, for example with a digital noise-shaping filter applying a high-pass digital filter to a pseudo-random binary sequence. The digital dither generation circuit may alternatively be implemented by one or more 1-bit sigma-delta modulators, each generating a bit of a digital dither sequence that is converted to analog.