Methods/systems employ randomly jittered under-sampling to reduce a sampling rate required to estimate the amplitude of high-frequency signals in circuit breakers, power meters, and other digital signal processing applications. The methods/systems can greatly reduce the nominal sampling rate for applications where RMS, peak and mean estimates of the signal are desired for both the entire band-limited signal and separate estimates for each frequency component. This can in turn result in large cost savings, as less complex and thus less expensive controllers and related components may be used to perform the sampling. As well, the methods/systems herein can provide reasonably accurate waveform estimates that allow additional cost savings in bill of materials (BOM) and printed circuit board assembly (PCBA) footprint and real-estate by eliminating the need for certain analog components, such as signal conditioning components.

A signal processing circuit includes: a plurality of A/D conversion units of a plurality of channels, each of plurality of the A/D conversion units including an amplifier configured to amplify an input analog signal and an A/D converter configured to convert an output signal from the amplifier into a digital signal, wherein at least one of operation parameters of the amplifier and the A/D converter is set individually for each of the plurality of channels.

A device and method for processing a signal, the method including, by a modulator (1250), receiving an analog signal, modulating the analog signal, and outputting a data frame (1258); receiving, by a counter (1368), the data frame from the modulator and outputting at least two data word sets (1370) each in accordance with a respective one of at least two counter clocks (1372); filtering, by each of at least two digital filter sets (1374), a respective data word set of the at least two data word sets received from the counter, and each outputting, to a switch (1378), a respective filtered data word set (1376). The switch may be configured to select, as an output, one of the filtered data word sets. The switch may be configured to change to a different selected filtered data word set upon detection of a change in line frequency and/or phase.

A variable output data rate converter circuit preferably meets performance requirements while keeping the circuit complexity low. In some embodiments, the converter circuit may include an oversampling sigma delta modulator circuit to quantize an analog input signal at an oversampled rate, and output an sigma delta modulated signal, a transposed polynomial decimator circuit to decimate the sigma delta modulated signal, and output a first decimated signal, and an integer decimator circuit to decimate the first decimated signal by an integer factor and output a second decimated signal having a desired output data rate. The transposed polynomial decimator circuit has a transposed polynomial filter circuit and a digital phase locked loop circuit, which tracks a ratio between a sampling rate of the first decimated signal and the oversampled rate, and outputs an intersample position parameter to the transposed polynomial filter circuit.

An apparatus comprises a sigma-delta analog-to-digital converter (ADC) circuit including a serial data input, a serial data output, a serial clock input to receive a serial clock signal, and a master clock input to receive a master clock signal; a digital isolator circuit including outputs coupled to the serial clock input and serial data input of the sigma-delta ADC circuit, and an input coupled to the serial data output of the sigma-delta ADC circuit; an oscillator circuit unconnected to the digital isolator circuit and configured to generate the master clock signal asynchronous to the serial clock input signal; and wherein the sigma-delta ADC circuit generates an ADC sampling clock using the master clock.

An apparatus comprises a sigma-delta analog-to-digital converter (ADC) circuit including a serial data input, a serial data output, a serial clock input to receive a serial clock signal, and a master clock input to receive a master clock signal; a digital isolator circuit including outputs coupled to the serial clock input and serial data input of the sigma-delta ADC circuit, and an input coupled to the serial data output of the sigma-delta ADC circuit; an oscillator circuit unconnected to the digital isolator circuit and configured to generate the master clock signal asynchronous to the serial clock input signal; and wherein the sigma-delta ADC circuit generates an ADC sampling clock using the master clock.

An input stage circuit for a sigma-delta analog-to-digital converter circuit receives a digital-to-analog converter generated feedback signal and an analog current input signal to generate a difference signal applied to an integrator circuit. A single bit quantization circuit quantizes an output of the integrator circuit to generate a bit signal that is applied to an input of the digital-to-analog converter. The input stage circuit includes a switched input capacitor controlled by first and second, non-overlapping, clock signals.

Chopping techniques that suppress fold-back into the signal band and spreads the offset across the spectrum are described. By using various techniques, chopping may be performed with a variable frequency clock to spread the offset across the signal spectrum. Spreading the offset across the signal spectrum means that there are no longer large spurious tones at a few frequencies.

Methods/systems employ randomly jittered under-sampling to reduce a sampling rate required to estimate the amplitude of high-frequency signals in circuit breakers, power meters, and other digital signal processing applications. The methods/systems can greatly reduce the nominal sampling rate for applications where RMS, peak and mean estimates of the signal are desired for both the entire band-limited signal and separate estimates for each frequency component. This can in turn result in large cost savings, as less complex and thus less expensive controllers and related components may be used to perform the sampling. As well, the methods/systems herein can provide reasonably accurate waveform estimates that allow additional cost savings in bill of materials (BOM) and printed circuit board assembly (PCBA) footprint and real-estate by eliminating the need for certain analog components, such as signal conditioning components.

Methods/systems employ randomly jittered under-sampling to reduce a sampling rate required to convert an analog signal to a digital signal in electronic devices and other applications that perform digital signal processing on the signal. The methods/systems can greatly reduce the nominal sampling rate for such applications where RMS, peak and mean estimates of the signal are desired for both the entire band-limited signal and separate estimates for each frequency component. This can in turn result in large cost savings, as less complex and thus less expensive controllers and related components may be used to perform the sampling. As well, the methods/systems herein can provide reasonably accurate waveform estimates that allow additional cost savings in bill of materials (BOM) and printed circuit board assembly (PCBA) footprint and real-estate by eliminating the need for certain analog components, such as signal conditioning components.