A sigma-delta analog-to-digital converter includes: a subtractor for subtracting a feedback signal from an analog input signal; a loop filter for processing the output signal from the subtractor to generate a filtered signal; a signal comparing circuit for selectively operating in an offset detection mode or a signal comparison mode, wherein the signal comparing circuit generates an error signal irrelevant to the relative magnitude between the filtered signal and a reference signal in the offset detection mode, and generates a comparison signal corresponding to the relative magnitude between the filtered signal and the reference signal in the signal comparison mode; an offset calibration control circuit for calibrating the offset of the signal comparing circuit and for controlling the signal comparing circuit to alternately switch between the offset detection mode and the signal comparison mode; and a digital-to-analog converter for generating the feedback signal according to the comparison signal.

Included are a loop filter, a quantization circuit section, and a current steering digital-analog conversion section. The quantization circuit section converts a loop filter output into a digital value. The current steering digital-analog conversion section is provided in a feedback loop that feeds back the output of the quantization circuit section to the loop filter. Then, each of the analog-digital converters includes a first input signal current path, a second input signal current path, a first feedback current path, and a second feedback current path. The first input signal current path feeds a first input signal current to an input end of a first stage integrator of the loop filter. The second input signal current path feeds a second input signal current, a current opposite in sign to the first input signal current, to an input end of a second stage integrator of the loop filter. The first feedback current path connects one feedback output end of the current steering digital-analog conversion section to the input end of the first stage integrator of the loop filter. The second feedback current path connects other feedback output end of the current steering digital-analog conversion section to the input end of the second stage integrator of the loop filter.

An isolator of embodiments includes a analog-digital converter configured to convert an analog signal into a digital signal of one bit and transmit the digital signal of one bit as normal data, a time direction multiplexing circuit configured to perform time direction multiplexing of alternately performing conversion of the normal data into a digital differential signal and transmission of the digital differential signal, and transmission of a special signal different from the normal data, and an insulated transmission circuit configured to transmit the digital differential signal and the special signal transmitted from the time direction multiplexing circuit via an insulating layer.

The invention provides a signal processing system, for transferring analog signals from a probe to a remote processing unit. The system comprises a first ASIC at a probe, which is adapted to receive an analog probe signal. The first ASIC comprises an asynchronous sigma-delta modulator, wherein the asynchronous sigma-delta modulator is adapted to: receive the analog probe signal; and output a binary bit-stream. The system further comprises a second ASIC at the remote processing unit, adapted to receive the binary bit-stream. The asynchronous may further include a time gain function circuit, the first ASIC may further comprise a multiplexer, the second ASIC may further comprise a time-to-digital converter. The time to digital converter may be a pipelined time-to-digital converter.

A sigma-delta modulator includes an N-bit quantization circuit that generates a stream of N-bit code words and a feedback signal path with an N-bit DAC circuit, having a non-ideal operation due to mismatch error, that converts the stream of N-bit code words to generate a feedback signal. A digital DAC copy circuit provides a digital replication of the N-bit DAC circuit. The digital replication accounts for the non-ideal operation of the N-bit DAC circuit 126 due to mismatch error, and converts the stream of N-bit code words to generate a stream of P-bit code words, where P>N, that are functionally equivalent to the feedback signal output from the N-bit DAC circuit.

A modem chip communicates with a radio frequency (RF) chip and includes a digital interface configured to receive data including a plurality of samples from the RF chip based on digital communication. A logic block generates a frame synchronization signal based on a clock signal in the modem chip, provides the generated frame synchronization signal to the digital interface, and receives the plurality of samples in synchronization with the frame synchronization signal.

A battery-operated device comprises: a first battery cell having a voltage; a second battery cell having a voltage; a first anti-aliasing filter operable to be coupled to the first battery cell; a second anti-aliasing filter operable to be coupled to the second battery cell; an analog-to-digital converter operable to be coupled to the first anti-aliasing filter during a first period of time or the second anti-aliasing filter during a second period of time different than the first period of time; and wherein the second anti-aliasing filter is charged during the first period of time and the first anti-aliasing filter is charged during the second period of time.

An analog to digital converter (ADC) includes voltage and reference input terminals, a buffer circuit, and control logic. The buffer circuit includes input and output terminals and a variable resistor including resistive branches connected in parallel. The control logic is configured to, in a calibration phase, determine a given gain value for which gain error is to be calibrated, determine a set of the resistive branches in the buffer circuit to be used to achieve the given gain value, successively enable a different resistive branch of the variable resistor of the set until all resistive branches of the set have been enabled, determine an output code resulting after enabling all resistive branches of the set, and, from the output code, determine a gain error of the given gain value. The control logic is further configured to take corrective action based upon the gain error of the given gain value.

In some examples, a sigma-delta analog-to-digital converter (ADC), comprises a first set of switches configured to receive a first voltage signal; a second set of switches coupled to the first set of switches at a first node and a second node, the second set of switches configured to receive a second voltage signal; an integrator including a first input sampling capacitor coupled to the first node and a second input sampling capacitor coupled to the second node, wherein the integrator configured to generate a first output signal. The sigma-delta ADC further comprises a comparator coupled to the integrator and configured to generate a second output signal based on the first output signal; and a controller unit having a first counter, a second counter, and a processor, the controller unit coupled to the first and second sets of switches, the integrator, and the comparator.

A compressive sensing image sensor includes: a pixel array; and a readout circuit configured to receive pixel data on a shot image in an analogue form, and to process the pixel data, wherein the pixel array includes a plurality of blocks each having a plurality of pixels and arranged in an array form, wherein the circuit includes: a compressive sensing multiplexer to which a plurality of pixel data outputted from a corresponding block from among the plurality of blocks are inputted; an LFSR configured to arbitrarily select at least one pixel data from the plurality of pixel data inputted to the compressive sensing multiplexer; and a delta-sigma ADC configured to receive the at least one pixel data selected by the LFSR, to delta-sigma modulate the received at least one pixel data, and to generate compressive sensing data for restoring an image of the corresponding block from among the shot images.