A signal processing structure and method are presented. A first digital filter operates on received sigma-delta modulated (SDM) input signals. A second pre-processing digital filter receives a SDM input signal, directly low pass filter the SDM input signal and provides an output SDM signal. The output sigma-delta modulated signal is provided as an input for said first digital filter. In standard digital systems operating with digital microphones, filtering of the microphones' output signal requires to first convert the signal into pulse code modulation (PCM), then filter and finally convert back to pulse density modulation (PDM). This approach increases the latency of the system because decimation and interpolation must be performed in order to pass from PDM to PCM. By using filters that operate directly on the oversampled PDM output of the digital microphones it is possible to reduce the latency of the system and minimize the hardware area.

In an embodiment, an ADC converter includes a first injection branch and a second injection branch, a first feedback branch and a second feedback branch, an integration node connected to the first and second injection branches and the first and second feedback branches, an integrator connected to the integration node and a comparator connected downstream of the integrator and configured to generate a comparator output signal to control the first and second feedback branches, wherein the first and second injection branches are configured to provide a charge injection dependent on a respective input quantity to the integration node, wherein the input quantity of the first injection branch is selected from a differential voltage signal, a capacitance dependent signal and a current dependent signal, wherein the input quantity of the second injection branch is selected from another one of the differential voltage signal, the capacitance dependent signal and the current dependent signal, and wherein the first and second feedback branches are configured to provide a feedback charge injection dependent on the comparator output signal to the integration node, the first and second feedback branches configured to receive one of a fixed voltage signal or a differential voltage signal.

A circuit device includes a selector to which first to n-th voltages are input, an A/D converter circuit to which output voltages of the selector are input as input voltages, and first to n-th quantization error hold circuits that hold charges corresponding to quantization errors in A/D conversion of the first to n-th voltages. The A/D converter circuit performs A/D conversion of an input voltage by a successive approximation operation using a charge redistribution type D/A converter circuit and performs k-th A/D conversion on an i-th voltage by using a charge held in an i-th quantization error hold circuit in (k1)th A/D conversion of the i-th voltage to output A/D conversion result data DOUT in which the quantization error is noise-shaped.

A circuit device includes an A/D converter circuit that performs A/D conversion by successive approximation using a charge redistribution type D/A converter circuit having capacitor array circuits on the positive electrode side and the negative electrode side, and quantization error hold circuits that hold charges corresponding to a quantization error in the A/D conversion. The quantization error hold circuits include quantization error hold circuits on the positive electrode side and the negative electrode side having one ends connected to sampling nodes of the capacitor array circuits on the positive electrode side and the negative electrode side. The quantization error hold circuits on the positive electrode side and the negative electrode side are placed on a second direction side orthogonal to a first direction in which the capacitor array circuits on the positive electrode side and the negative electrode side are placed.

The present disclosure relates to a time-division multiplexing (TDM)-based multi-channel electrocardiogram measurement apparatus and method, which remove the influence of power line interference in a way to implement multiple channels by using a TDM method, remove an electrode DC offset (EDO) through a pre-charged capacitor, and periodically take a current out or supply a current. The TDM-based multi-channel electrocardiogram measurement apparatus and method robust against power line interference according to the present disclosure have advantages in that it can measure electrocardiogram by using multiple channels with low power and high integration based on TDM, can perform contactless measurement because an EDO is efficiently eliminated and high impedance is satisfied, and has a characteristic robust against power line interference.

A sigma-delta ADC circuit with an analog loop filter circuit can be multiplexed between different inputs by flushing the memory of the analog loop filter integrators and the digital decimation filter and filling it with new data for the current input. However, filling the memory can be slow with respect to the sampling frequency because the information about past history has to be built up before meaningful output data can be generated. Thus, the multiplexing rate between channels using a sigma-delta ADC circuit can be slowed by such memory flushing. A multiplexed sigma-delta ADC circuit is described that can overcome these problems so as to be able to support cycle-by-cycle sampling of multiple channels. These techniques can provide a fast sigma-delta analog-to-digital converter (ADC) circuit that is small in area and that can multiplex over a number of channels dynamically.

A circuit device includes a selector to which first to n-th voltages are input, an A/D converter circuit to which output voltages of the selector are input as input voltages, and first to n-th quantization error hold circuits that hold charges corresponding to quantization errors in A/D conversion of the first to n-th voltages. The A/D converter circuit performs A/D conversion of an input voltage by a successive approximation operation using a charge redistribution type D/A converter circuit and performs k-th A/D conversion on an i-th voltage by using a charge held in an i-th quantization error hold circuit in (k1)th A/D conversion of the i-th voltage to output A/D conversion result data DOUT in which the quantization error is noise-shaped.

A circuit device includes an A/D converter circuit that performs A/D conversion by successive approximation using a charge redistribution type D/A converter circuit having capacitor array circuits on the positive electrode side and the negative electrode side, and quantization error hold circuits that hold charges corresponding to a quantization error in the A/D conversion. The quantization error hold circuits include quantization error hold circuits on the positive electrode side and the negative electrode side having one ends connected to sampling nodes of the capacitor array circuits on the positive electrode side and the negative electrode side. The quantization error hold circuits on the positive electrode side and the negative electrode side are placed on a second direction side orthogonal to a first direction in which the capacitor array circuits on the positive electrode side and the negative electrode side are placed.

The present disclosure relates to a time-division multiplexing (TDM)-based multi-channel electrocardiogram measurement apparatus and method, which remove the influence of power line interference in a way to implement multiple channels by using a TDM method, remove an electrode DC offset (EDO) through a pre-charged capacitor, and periodically take a current out or supply a current. The TDM-based multi-channel electrocardiogram measurement apparatus and method robust against power line interference according to the present disclosure have advantages in that it can measure electrocardiogram by using multiple channels with low power and high integration based on TDM, can perform contactless measurement because an EDO is efficiently eliminated and high impedance is satisfied, and has a characteristic robust against power line interference.

A multiplexed sigma-delta analog-to-digital converter (ADC) is provided for digitizing analog input signals of at least two input channels. The ADC includes input circuitry that obtains samples of the input channels and an integrator chain. The integrator chain includes a first delaying integrator and a second delaying integrator. The first delaying integrator processes a sample of one of the two input channels at a time. A first non-delaying integrator is disposed in the integrator chain either between the first delaying integrator and the second delaying integrator or after the second delaying integrator. A clocking arrangement includes a first clock set and a second clock set. Channel selection clocks included in the second clock set are delayed in comparison to the respective channel selection clocks included in the first clock set in order to prevent data from being mixed between consecutive full clock cycles.