An analog input signal (X.sub.(n)) is processed by a Peak to Average Ratio Reduction (PARR) block to diminish the difference between peak amplitudes and average amplitudes of the analog input signal (X.sub.(n)). After, a distorted signal (h(n)) having low peak to average amplitude ratio, generated at the PARR block output, is processed by a delta sigma modulation (DSM) block converts the distorted signal (h(n)) into a digitally modulated distorted signal (h_dsm.sub.(n)) with high signal to noise ratio (SNR). Afterwards, the digitally modulated distorted signal (h_dsm.sub.(n)) is corrected and amplified by a Class-D RF power amplifier fed by a feeding signal (env.sub.(n)) generated from a digital correction signal (z_dsm.sub.(n)). As a result, a digitally modulated signal (y(n)) with high signal to noise ratio (SNR) of the analog input signal (X.sub.(n)) is generated at the output of the Class-D RF power amplifier.

A modulator circuit includes a plurality of signal processing branches, each branch having a modulator for performing a delta-sigma modulation of a respective data stream portion in order to generate a modulated signal. The modulator circuit receives an input data stream having a carrier frequency; splits the input data stream into a plurality of data stream portions. Delta-sigma modulation is performed in each branch on a respective data stream portion. The respective modulated signals from each branch are combined to form an output signal for outputting at the carrier frequency.

A latched comparator comprises a pre-amplifier stage with a positive input (V.sub.in,p), a negative input (V.sub.in,n); and a differential output (V.sub.out) comprising a first output (V.sub.out,1) and a second output (V.sub.out,2), the pre-amplifier stage comprising a first cascode pair, comprising a first amplifying transistor (MN2) and a first cascode transistor (MN4) connected at a first cascode node, the first amplifying transistor (MN2) being controlled by the positive input (V.sub.in,p) and the first cascode transistor (MN4) being connected, opposite to the first cascode node, to the first output (V.sub.out,1); a second cascode pair, comprising a second amplifying transistor (MN3) and a second cascode transistor (MN5) connected at a second cascode node, the second amplifying transistor (MN3) being controlled by the negative input (V.sub.in,n) and the second cascode transistor (MN5) being connected, opposite to the second cascode node, to the second output (V.sub.out,2); a first gain-boosting transistor (MN6) connected between the first output (V.sub.out,1) and the first cascode node; and a second gain-boosting transistor (MN7) connected between the second output (V.sub.out,2) and the second cascode node, wherein the first gain-boosting transistor (MN6) and the second gain-boosting transistor (MN7) are cross-coupled, so that the first gain-boosting transistor (MN6) is controlled by the second output (V.sub.out,2) and the second gain-boosting transistor (MN7) is controlled by the first output (V.sub.out,2).

Transimpedance amplifiers with feedforward current are provided herein. In certain embodiments, an amplifier system includes a transimpedance amplifier that amplifies an input current received at an input to generate an output voltage at an output. The amplifier system further includes a controllable current source that is coupled to the output of the transimpedance amplifier, and operable to provide a feedforward current that changes in relation to the input current of the transimpedance amplifier. By providing a feedforward current in this manner, gain and speed performance of the transimpedance amplifier is enhanced.

An apparatus in a PWM modulator includes a triangular wave generator that generates a triangular wave and a comparator that is responsive to a signal input to generate a signal output. An output of the PWM modulator is responsive to the comparator signal output. A polarity inversion circuit, coupled between the triangular wave generator and the comparator, is configured in one of the following ways: to provide the triangular wave to the comparator when the triangular wave has a first slope polarity and to provide a polarity-inverted version of the triangular wave to the comparator when the triangular wave has a second slope polarity opposite the first slope polarity; and to provide the signal input to the comparator when the triangular wave has the first slope polarity and to provide a polarity-inverted version of the signal input to the comparator when the triangular wave has the second slope polarity.

A PWM modulator has a quantizer that generates a PWM output signal to speaker driver. When a first voltage swing range is supplied to the speaker driver, the quantizer analog gain is controlled to be a first gain value. When a second PWM drive voltage swing range is supplied to the speaker driver, the analog gain is controlled to be a second gain value. The first and second gain values of the analog gain of the quantizer cause the combined gain of the quantizer and driver to be approximately equal in the two modes. The quantizer has at least two gain-affecting measurable non-ideal characteristics. The quantizer is adjustable using measured first and second values to correct for first and second of the at least two non-ideal characteristics. The gain of the quantizer is calibratable while the quantizer is adjusted using the measured first and second measured values.

An apparatus in a PWM modulator includes a triangular wave generator that generates a triangular wave and a comparator that is responsive to a signal input to generate a signal output. An output of the PWM modulator is responsive to the comparator signal output. A polarity inversion circuit, coupled between the triangular wave generator and the comparator, is configured in one of the following ways: to provide the triangular wave to the comparator when the triangular wave has a first slope polarity and to provide a polarity-inverted version of the triangular wave to the comparator when the triangular wave has a second slope polarity opposite the first slope polarity; and to provide the signal input to the comparator when the triangular wave has the first slope polarity and to provide a polarity-inverted version of the signal input to the comparator when the triangular wave has the second slope polarity.

According to an aspect, an audio amplifier includes a first sigma-delta modulator configured to receive a digital audio signal and generate a first multi-level output signal based on the audio signal, and a second sigma-delta modulator configured to receive the first multi-level output signal from the first sigma-delta modulator and generate a second multi-level output signal. The second multi-level output signal has a number of levels less than a number of levels of the first multi-level output signal.

An automatic gain control system for a receiver for an asymmetrical and/or unbalanced constellation, the system including: an automatic gain control loop adapted to be coupled to both a first transimpedance amplifier coupled to a first analog-to-digital converter forming a first tributary and a second transimpedance amplifier coupled to a second analog-to-digital converter forming a second tributary; wherein the automatic gain control loop is operable for providing an offset gain control voltage to gain balance a transimpedance amplifier voltage and a power associated with the first tributary and a transimpedance amplifier voltage and a power associated with the second tributary. The automatic gain control loop includes an analog automatic gain control loop. The automatic gain control loop is implemented in hardware or firmware.

The disclosure relates to technology for an adjustable gain device that includes differential input terminals, differential output terminals, signal processing circuitry, and first and second cross-coupled segments. The first cross-coupled segment is coupled between differential input terminals of the adjustable gain device and a negative input of the signal processing circuitry. The second cross-coupled segment is coupled between differential input terminals of the adjustable gain device and a positive input of the signal processing circuitry. The adjustable gain device has a gain that is adjustable by adjusting values of the first and second cross-coupled segments, while maintaining a substantially consistent frequency response and a substantially consistent input impedance of the adjustable gain device, so long as a specified relationship between values of the first and second cross-coupled segments is kept substantially constant.