Successive approximation sigma delta analog-to-digital converters

A method comprising:

• receiving an analog input signal and converting the analog input signal to a first digital signal at a first analog-to-digital converter;
• performing a successive approximation to generate the first digital signal via the first analog-to-digital converter;
• converting an analog output of the first analog-to-digital converter to a second digital signal via a second analog-to-digital converter, wherein the second analog-to-digital converter is a fine conversion analog-to-digital converter relative to the first analog-to-digital converter;
• suppressing noise of the second analog-to-digital converter via a decimation filter;
• performing a delta-sigma conversion via the second analog-to-digital converter to generate a second digital signal based on the analog output of the first analog-to-digital converter, wherein the analog output of the first digital-to-analog converter is generated based on the analog input signal;
• and
• combining the first digital signal and the second digital signal to provide a resultant output signal.

An analog-to-digital converter comprising:

• a digital-to-analog converter circuit configured to convert a plurality of bits of a digital signal to an analog signal;
• a sample and hold circuit to sample an analog input signal;
• a subtractor configured to subtract the analog signal from an output of the sample and hold circuit;
• wherein the digital-to-analog converter circuit comprises
• a first digital-to-analog converter configured to convert a first most-significant-bit of the plurality of bits;
• a second digital-to-analog converter configured to convert a first least-significant-bit of the plurality of bits, wherein the second digital-to-analog converter is a delta-sigma digital-to-analog converter;
• an amplifier configured to amplify an output of the digital-to-analog converter circuit;
• a latch configured to latch an output of the amplifier;
• and
• a successive approximation module configured to (i) receive an output of the latch, and (ii) perform successive approximations to generate the digital signal.