A chopper circuit (100) for a multipath chopper amplifier (201) is described. The chopper circuit (100) comprises a first chopper device (110) in a first circuit path (111), wherein the first chopper device (110) is configured to be controlled by a first clock signal (315), which has a first frequency; and a second chopper device (120) in a second circuit path (121), parallel to the first circuit path (111), wherein the second chopper device (120) is configured to be controlled by a second clock signal (325), which has a second frequency, wherein the first frequency is greater than the second frequency. Furthermore, a corresponding method of chopping an input signal (102) is described.

Systems and methods for direct signal down-conversion and decimation in a digital receiver. The digital receiver produces a decimated passband version of the signal without the problems associated with use of digital mixers. The digital receiver includes a passband-to-passband decimator/down-converter that implements an algorithm which takes the signal band (frequency and bandwidth or lower and upper frequencies) where a signal is present and produces a decimation rate and phase for use by a low-pass mixer-free down-conversion. The digital receiver technology may be efficiently implemented on a digital signal processor or field-programmable gate array.

An isolator of embodiments includes a ΔΣ 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.

A gain stage, such as an amplifier, e.g., an instrumentation amplifier, can receive an input signal and adjust the level of the input signal, e.g., amplify or attenuate. An output voltage of the gain stage can be applied to a subsequent circuit. Using various techniques, a second stage of an instrumentation amplifier, which can include a transconductance stage that converts a current to a voltage that can be applied to an output node of the instrumentation amplifier, can be removed. Removal of such a second stage can allow an output current from the gain stage to be applied directly from a current output node to an input node of a subsequent circuit.

A signal processing system may include a sensor readout channel configured to convert an electronic signal into a digital quantity. The sensor readout channel may include a first-order sigma-delta modulator having a modulator input and a modulator output, first outside chopping switches located at the modulator input, second outside chopping switches located at the modulator output, an auxiliary path comprising an analog-to-digital converter (ADC) having an auxiliary path input and an auxiliary path output, the auxiliary path input configured to receive as its input signal a signal output by a memory element of the first-order sigma-delta modulator, and a signal combiner configured to combine a modulator output signal generated by the first-order sigma-delta modulator with an auxiliary path output signal generated by the auxiliary path to generate a combined output signal.

The invention provides a system improving signal handling, e.g., transmission and/or processing. In an embodiment, the system may include a filter circuit, a magnitude bit truncation circuit and a utility circuit. The filter circuit may be coupled to a target signal which contains one or more desired signals at one or more interested bands, for attenuating each said interested band to form a filtered signal. The magnitude bit truncation circuit may be coupled to the filter circuit, for truncating one or more bits of each sample of the filtered signal to form a truncated signal. The utility circuit may be coupled to the magnitude bit truncation circuit, for handling the truncated signal to implement handling of the target signal, so as to reduce resource requirement and enhance error tolerance comparing with directly handling the target signal.

A device includes a sensor configured to output an analog sensor signal, an analog-to-digital converter circuit configured to convert the analog sensor signal into a sigma-delta-modulated digital signal having a bit width of n bits, and a pulse width modulator configured to generate a pulse-width-modulated signal based on the sigma-delta-modulated digital signal.

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 system includes an analog-to-digital converter configured to convert an analog signal generated by a digital sensor into a digital signal, and a testing apparatus configured to be enabled after the analog-to-digital converter operates in a testing mode, wherein the testing apparatus comprises a filter configured to receive the digital signal from the analog-to-digital converter, and apply a filtering process to the digital signal, a control circuit configured to terminate the filtering process after an output of the control circuit reaches a predetermined reference value, and a result register configured to receive a result generated by the filter after the control circuit terminates the filtering process.

Systems and methods for low power sample rate conversion are based on a noise shaping technique. A sample rate conversion circuit includes a clock synchronization circuit configured to receive an input sample sequence at a first sample rate and generate a valid sample sequence that is sampled at a second sample rate different from the first sample rate. The valid sample sequence may include valid samples from a registered sequence sampled at an oversampled rate greater than the first sample rate with invalid samples in the registered sequence being excluded from the valid sample sequence. The sample rate conversion circuit also includes a noise shaping circuit coupled to the clock synchronization circuit and configured to encode the valid sample sequence into a noise-shaped output sequence at the second sample rate by suppressing quantization noise from the valid sample sequence.