Multi-bit successive approximation ADC

An n-bit analog-to-digital converter (ADC) circuit for converting an analog input signal to a digital output signal in a number of successive approximation cycles, the n-bit ADC circuit comprising:

• a digital-to-analog converter (DAC) circuit configured to generate a DAC analog signal by converting a DAC digital signal to the DAC analog signal;
• an input capacitor configured to be pre-charged to at least one of the analog input signal and the DAC analog signal;
• a programmable gain amplifier (PGA) circuit configured to amplify an error signal including a difference between the analog input signal and the DAC analog signal, wherein the PGA circuit is configured to change a gain of the PGA circuit during at least some of the successive approximation cycles;
• a multi-bit flash ADC circuit configured to convert the amplified error signal to a multi-bit digital signal;
• and
• a successive approximation register (SAR) circuit configured to use the multi-bit digital signal to generate, in at least some of the successive approximation cycles, at least one of a DAC digital signal and the digital output signal,
• wherein n represents a positive integer greater than one.

A method of converting an analog input signal to a digital output signal, comprising:

• operating a successive approximation analog-to-digital converter (ADC) circuit to process more than one bit per cycle, the cycle being a successive approximation cycle, the operating comprising:
• operating a capacitive digital-to-analog (DAC) array of the ADC circuit as a plurality of decomposed capacitive sub-DAC circuits, during one or more first cycles;
• and
• merging the plurality of decomposed capacitive sub-DAC circuits of the capacitive DAC array, during one or more last cycles.

A method of converting an analog input signal to a digital output signal, comprising:

• operating a successive approximation analog-to-digital converter (ADC) circuit to process more than one bit per cycle, the cycle being a successive approximation cycle, the operating comprising:
• converting a first digital signal to a first analog signal;
• amplifying an error signal, the error signal comprising a difference between the analog input signal and the first analog signal;
• converting the amplified error signal to a multi-bit digital signal;
• and
• generating, in at least some of the cycles, at least one of a digital signal and the digital output signal based on the multi-bit digital signal,
• wherein a gain associated with the amplifying is increased during at least some of the cycles.

An analog-to-digital converter (ADC) circuit for converting an analog input signal to a digital output signal in a number of cycles, the ADC circuit comprising:

• a digital-to-analog (DAC) circuit including a corresponding number of capacitive elements, the capacitive elements configured to be pre-charged, the corresponding number of capacitive elements grouped into a number of capacitive sub-DAC circuits;
• a plurality of comparators coupled to the capacitive sub-DAC circuits;
• a plurality of first switches configured to merge the capacitive sub-DAC circuits during a last portion of the cycles;
• and
• a processing circuit configured to receive an output signal from at least some of the comparators and to generate at least one of a digital output signal and one or more digital signals.

An analog-to-digital converter (ADC) circuit for converting an analog input signal to a digital output signal in a number of cycles, the ADC circuit comprising:

• a digital-to-analog converter (DAC) circuit configured to convert a DAC digital signal to a DAC analog signal;
• a capacitor configured to be pre-charged to at least one of the analog input signal and the DAC analog signal;
• an amplifier circuit configured to amplify an error signal;
• a multi-bit ADC circuit configured to convert the amplified error signal to a multi-bit digital signal;
• and
• a processing circuit configured to use the multi-bit digital signal to generate at least one of a DAC digital signal and the digital output signal.