A new cascaded sigma delta modulator structure using multi-bit quantizers combined with single-bit feedback

A new cascaded structure is presented using two multi-bit quantizers in its two stages. In the first stage only the most-significant-bit of the quantizer output is used in the feedback loop, so high linearity can be achieved just as using a single-bit quantizer. Furthermore, as the first stage uses a multi-bit quantizer, the quantization error is very small. Thus this quantization error could be amplified by a gain A before it is sent to the second stage. Using a digital error cancelling network, the quantization error of the second stage can be reduced by a factor of 1/A