A delta-sigma modulator may include a loop filter, a quantizer, an input gain element having a programmable input gain and coupled between an input of the delta-sigma modulator and an input of the loop filter, a feedforward gain element having a programmable feedforward gain and coupled between the input of the delta-sigma modulator and an output of the loop filter, and a quantizer gain element having a quantizer gain and coupled between the output of the loop filter and an input of the quantizer. The programmable input gain is controlled in order to control a variable gain of the delta-sigma modulator. The programmable feedforward gain is controlled to be equal to the ratio of the programmable input gain and the quantizer gain such that the delta-sigma modulator has a fixed phase response.

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.

An incremental analog-to-digital converter including a first-stage non-delay memorization element and other elements is disclosed. An ending time point of a second reset signal received by the first-stage non-delay memorization element is later than an ending time point of a first reset signal received by the other elements by at least one clock cycle, a reset duration of the first-stage non-delay memorization element is longer than a reset duration of the other element, so that the first-stage non-delay memorization element can be prevented from occurring overshoot or spike on an output thereof, and the incremental analog-to-digital converter can maintain a good signal-to-noise and distortion ratio under the condition that the internal elements has low swing limits.

An incremental analog-to-digital converter including a first-stage non-delay memorization element and other elements is disclosed. An ending time point of a second reset signal received by the first-stage non-delay memorization element is later than an ending time point of a first reset signal received by the other elements by at least one clock cycle, a reset duration of the first-stage non-delay memorization element is longer than a reset duration of the other element, so that the first-stage non-delay memorization element can be prevented from occurring overshoot or spike on an output thereof, and the incremental analog-to-digital converter can maintain a good signal-to-noise and distortion ratio under the condition that the internal elements has low swing limits.

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 sigma delta modulator comprises an input configured to receive an input analog signal; a summing junction configured to subtract a feedback analog signal from the input analog signal; a first stage including a low pass filter coupled to the summing junction, wherein the low pass filter is configured to generate a first filtered signal; a second stage coupled to the low pass filter, configured to generate a second filtered signal by an active filter; a back-end stage coupled to the second stage, wherein the back-end stage comprises an analog to digital converter configured to convert the 2.sup.nd filtered signal to a digital output signal by sampling at a predetermined sampling frequency(fs); and a feedback path for routing the digital output signal to the summing junction, wherein the feedback path comprises a digital to analog converters, DAC, converting the digital output signal to the feedback analog signal.

During a sampling phase, an analog front end circuit connects input of a first sampling capacitor to an analog input signal and input of a second sampling capacitor to a reference signal, and connects first and second hold capacitors to ground. During a partial tracking phase, input of the first sampling capacitor is connected to the reference voltage and the input of the second sampling capacitor is connected to the analog input signal. The first hold capacitor is connected to a first output of a gain amplifier and the second hold capacitor to a second output of the gain amplifier. Output of the first sampling capacitor is coupled to a first input of an amplifier and output of the second sampling capacitor is coupled to a second input of the amplifier.

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 sigma delta modulator comprises an input configured to receive an input analog signal; a summing junction configured to subtract a feedback analog signal from the input analog signal; a first stage including a low pass filter coupled to the summing junction, wherein the low pass filter is configured to generate a first filtered signal; a second stage coupled to the low pass filter, configured to generate a second filtered signal by an active filter; a back-end stage coupled to the second stage, wherein the back-end stage comprises an analog to digital converter configured to convert the 2.sup.nd filtered signal to a digital output signal by sampling at a predetermined sampling frequency (fs); and a feedback path for routing the digital output signal to the summing junction, wherein the feedback path comprises a digital to analog converters, DAC, converting the digital output signal to the feedback analog signal.

A calibration circuit, including: a signal generator circuit configured to generate a modulated analog input signal, which is based on a digital input word that is modulated; an Analog-to-Digital Converter (ADC) configured to convert an analog reference signal to a digital calibration word, wherein the analog reference signal is a low-pass-filtered version of the analog input signal generated by the signal generator circuit; and a feedback circuit configured to output the digital input word by adjusting the digital calibration word depending on a digital feedback signal, which is based on a modulated version of the analog reference signal, wherein the signal generator circuit, the ADC, and the feedback circuit are provided on a same chip.