A N-bit continuous-time sigma-delta modulator, SDM, (800) includes an input configured to receive an input analog signal (302); a first summing junction (304) configured to subtract a feedback analog signal (303) from the input analog signal (302); a loop filter (306) configured to filter an output signal from the first summing junction (304): an N-bit analog-to-digital converter, ADC, comprising at least one 1-bit ADC configured to convert the filtered analog output signal (309) to a digital output signal (314) where each 1-bit ADC comprises at least one pair of comparator latches (336, 356); and a feedback path (316) for routing the digital output signal to the first summing junction (304). The feedback path (316) includes a plurality of digital-to-analog converters, DACs, configured to convert the digital output signal (314) to an analog form. The ADC comprises or is operably coupled to, a calibration circuit (650, 840) coupled to an input and an output of the at least one pair of comparator latches (336, 356) and configured to apply respective calibration signals to individual comparator latches of the at least one pair of comparator latches (336, 356) in a time-Interleaved manner, and calibrate a comparator error of the comparator latches in response to a latched output of the respective calibration signals.

An embodiment converter circuit comprises an analog-to-digital signal conversion path. An input port receives an analog input signal having an offset, and an output port delivers a digital output signal quantized over M levels. The digital output signal is sensed by a digital-to-analog feedback path which comprises a digital-to-analog converter applying to the input port an analog feedback signal produced as a function of an M-bit digital word under control of a two-state signal having alternating first and second states. M-bit digital word generation circuitry coupled to the digital-to-analog converter and sensitive to the two-state signal produces, alternately, during the first states, a first M-bit digital word which is a function of the digital output signal quantized over M levels, and, during the second states, a second M-bit digital word which is a function a correction value of the offset in the analog input signal.

An apparatus including analog-to-digital conversion (ADC) circuitry is disclosed. The apparatus includes a plurality of comparators susceptible to offset variation and a shuffler circuit configured to shuffle input sources to the respective comparators. Feedback circuitry is also included and is configured and arranged with the ADC circuitry to detect offset variation in the outputs of each comparators for the shuffled inputs, relative to outputs of the plurality of comparators and compensate for the offset variation in the comparators based on the offset differences between the respective comparators.

A N-bit continuous-time sigma-delta modulator, SDM, (800) includes an input configured to receive an input analog signal (302); a first summing junction (304) configured to subtract a feedback analog signal (303) from the input analog signal (302); a loop filter (306) configured to filter an output signal from the first summing junction (304): an N-bit analog-to-digital converter, ADC, comprising at least one 1-bit ADC configured to convert the filtered analog output signal (309) to a digital output signal (314) where each 1-bit ADC comprises at least one pair of comparator latches (336, 356); and a feedback path (316) for routing the digital output signal to the first summing junction (304). The feedback path (316) includes a plurality of digital-to-analog converters, DACs, configured to convert the digital output signal (314) to an analog form. The ADC comprises or is operably coupled to, a calibration circuit (650, 840) coupled to an input and an output of the at least one pair of comparator latches (336, 356) and configured to apply respective calibration signals to individual comparator latches of the at least one pair of comparator latches (336, 356) in a time-Interleaved manner, and calibrate a comparator error of the comparator latches in response to a latched output of the respective calibration signals.

A sigma-delta analog-to-digital converter (ADC) includes a feed-forward circuit, a finite-impulse-response (FIR) digital-to-analog converter (DAC), and a decimation filter. The feed-forward circuit is configured to receive an analog input signal and a feedback signal and generate a set of digital signals. Each feedback element of the FIR DAC includes a flip-flop and a reset circuit. The reset circuit is configured to receive a corresponding reset signal of a set of reset signals and output a reference output signal when the corresponding reset signal is deactivated. The reset signal of each feedback element is deactivated sequentially after each cycle of a clock signal that is received by the flip-flop associated with a corresponding reset circuit of each feedback element. The feedback signal is generated based on the reference output signal. The decimation filter is configured to generate a digital output signal based on the set of digital signals.

Techniques to reduce the on-time of a multi-stage ADC circuit by combining the settling time of a signal conditioning circuit, e.g., buffer circuit, and the setting time of a residue amplifier when cancelling the offset of the signal conditioning circuit. The techniques can allow the signal conditioning circuit and the residue amplifier to settle together.

A circuit includes an operational amplifier and a resistor network coupled to an output of the operational amplifier. The resistor network includes a first set of resistors coupled between the output of the operational amplifier and a first node of the resistor network, wherein the resistors of the first set are electrically connected in series with each other, a second set of resistors coupled between the first node and a second node of the resistor network, wherein the resistors of the second set are electrically connected in series with each other and include a first number of resistors, a third set of resistors coupled between the second node and a third node of the resistor network, wherein the third node is coupled to a first voltage, and wherein the resistors of the third set are electrically connected in parallel with each other and include a second number of resistors, and a resistor coupled between the first node and the second node and arranged in parallel with the second set of resistors.

Described is an apparatus which comprises: a first integrator to receive an input signal and to generate a first output; a second integrator to receive the first output or a version of the first output and to generate a second output; and an analog-to-digital converter (ADC) to quantize the second output into a digital representation, the ADC including a detection circuit to detect an overload condition in the second output.

A D/A conversion circuit includes: an output terminal connected to an operational amplifier connected to a quantization circuit; a DAC capacitor; a selection switch switching among reference, first and second voltages to apply to the DAC capacitor as an analog potential; a ground switch connecting the DAC capacitor to a ground; and an output switch connecting the DAC capacitor to the output terminal. In a first period, the selection switch selects one of the reference, first and second voltages according to a quantization result value from the quantization circuit, and connects the one to the DAC capacitor, and the ground switch turns on to charge the DAC capacitor. In a second period, the selection switch selects another one of the first and second voltages, and connects the another one to the DAC capacitor, and the output switch turns on to output the analog potential to the output terminal.

A switched-capacitor integrator is described having the contribution to offset from the charge injection mismatch of switches connected to the summing nodes mitigated by using a switching scheme that conveys basically all the charge injection to the output, thus preventing net offset from being integrated.