A class-D amplifier includes measurement of speaker current via the low-side drive transistors of the amplifier. In one embodiment, a class-D amplifier includes two high-side transistors, two low-side transistors, a first sense resistor, a second sense resistor, and a sigma delta analog to digital converter (σΔ ADC). The two high-side transistors and two low-side transistors are connected as a bridge to drive a bridge tied speaker. The first sense resistor is connected between a first of the low-side transistors and a low-side reference voltage. The second sense resistor is connected between a second of the low-side transistors and the low-side reference voltage. The ΣΔ ADC is coupled to the bridge to measure voltage across the first sense resistor and the second sense resistor.

A digital filter for filtering a pulse density modulation (PDM) signal is presented. The filter has a first filter circuit to receive an input signal and to provide a filtered input signal at successive time steps which include a first filtered value at the first time step and a second filtered value at a second time step. The filter also has a quantizer to provide an output signal comprising output values at successive time steps and a filter variable circuit with a first multiplication circuit to receive the first filter variable, and divide the first filter variable by a first gain factor and a first summing circuit configured to receive the divided first filter variable, receive the output signal, and add the divided first filter variable and the first output value and a second multiplication circuit and a delay circuit.

A baseband processing unit includes a baseband processor configured to receive a plurality of component carriers of a radio access technology wireless service, and a delta-sigma digitization interface configured to digitize at least one carrier signal of the plurality of component carriers into a digitized bit stream, for transport over a transport medium, by (i) oversampling the at least one carrier signal, (ii) quantizing the oversampled carrier signal into the digitized bit stream using two or fewer quantization bits.

A circuitry for an incremental delta-sigma modulator includes at least an incremental delta-sigma modulator and a sample-and-hold element, the sample-and-hold element being arranged in front of the incremental delta-sigma modulator and providing an input voltage for the incremental delta-sigma modulator in the charged state, wherein the sample-and-hold element includes a capacitor for charging the input voltage for the incremental delta-sigma modulator, wherein a first switch is arranged in front of the capacitor, and a second switch is arranged behind the capacitor, wherein the first switch is open when the second switch is closed so as to provide, at the incremental delta-sigma modulator, an input voltage decreasing in amount, in particular a decaying input voltage, or wherein the second switch is open when the first switch is closed so as to charge the capacitor of the sample-and-hold element. In addition, a method of operating a circuitry for an incremental delta-sigma modulator is proposed.

A sensor circuit comprising a sensor input includes a delta-sigma analogue to digital converter. The delta-sigma analogue to digital converter includes a switched capacitor, a common mode voltage source, a reference voltage source, and a switch network. The switch network, in a first clock phase, connects the switched capacitor to charge it to either a sum or difference voltage, and in a second clock phase connects the switched capacitor to transfer charge into a summing junction. A controller controls the switch network responsive to a comparator output to selectively connect the switched capacitor to one of the common mode voltage and the reference voltage in the first clock phase. Implementations of the sensor circuit transfer charge every clock cycle and have low noise and high sensitivity.

A delta-sigma modulation apparatus performs delta-sigma modulation on a first signal as an input signal and outputs a second signal, outputs, using the second signal and a third signal generated through a transmission process of the second signal, a fourth signal that is an approximated value of a signal which is generated through at least part of the transmission process, and performs the delta-sigma modulation on the first signal using the fourth signal and outputs the second signal.

A digital conversion system including a sigma-delta converter, a signal generator providing a substantially symmetrical injection signal that is injected into the sigma-delta converter conversion path, bandpass filters for filtering the injection signal and the output of the sigma-delta converter, a correlator that correlates the filtered signals for providing an error signal, and a loop controller that uses the error signal to adjust a resonant frequency of the sigma-delta converter to output a target notch frequency. The loop controller may adjust a resonant frequency of a loop filter of the sigma-delta converter, in which the bandpass filters may each be centered at the target notch frequency at the output of the sigma-delta converter. The correlator may include a complex conjugate block, a multiplier and a mean calculator. The loop controller may include a converter and an amplifier and an integrator or a least-mean square block.

A device can include analog circuits formed with a substrate, including a comparator, analog switches, and a balance current circuit. A sensor current and balance current can be applied at an input of the comparator. The sensor current, balance current or both can be modulated with a switch control signal. Digital circuits can include switch control logic that generates the switch control signal in response to an output of the comparator and a modulation clock signal. Digital signal processing circuits can generate a multi-bit digital value from a bit stream output by the comparator circuit. The multi-bit digital value can be an analog-to-digital conversion of the sensor current. Corresponding methods and systems are also disclosed.

Provided is an AD converter, including: an analog signal input circuit, configured to be input with an analog input signal, and output a first analog output signal based on the analog input signal and a second analog output signal based on the analog input signal at different timing; an integral circuit, configured to integrate the first analog output signal and the second analog output signal and output the first integral signal and the second integral signal; a predictive circuit, configured to predict an integral signal output after the output by the integral circuit based on the first integral signal and the second integral signal output by the integral circuit, and output a predictive integral signal; and a quantization circuit, configured to generate a digital signal with the predictive integral signal quantized.

A continuous time, sigma-delta analog-to-digital converter circuit includes a sigma-delta modulator circuit configured to receive an analog input signal. A single bit quantizer of the modulator generates a digital output signal at a sampling frequency. A data storage circuit stores bits of the digital output signal and digital-to-analog converter (DAC) elements are actuated in response to the stored bits to generate an analog feedback signal for comparison to the analog input signal. A filter circuit includes polyphase signal processing paths and a summation circuit configured to sum outputs from the polyphase signal processing paths to generate a converted output signal. A fan out circuit selectively applies the stored bits from the data storage circuit to inputs of the polyphase signal processing paths of the filter circuit.