A digital filter and a method for filtering a pulse density modulation (PDM) signal are presented. The digital filter has a first filter circuit to receive an input signal with input values at successive time steps to provide a filtered input signal with filtered values at successive time steps. The digital filter does not require sample-rate or data format conversions. Also, the digital filter is area and power efficient when implemented in hardware. Optionally, the digital filter has a sigma-delta modulator including the quantiser, the sigma-delta modulator being used to receive the filtered input signal and to process the filtered input signal before and/or after being quantised by the quantiser. This digital filter does not require sample-rate or data format conversions. This digital filter is area and power efficient when implemented in hardware.

An integrator circuit includes: an operational amplifier; a first capacitor coupled to an input of the operational amplifier; a second capacitor coupled in parallel to the first capacitor so that a first terminal of the first capacitor is configured to be electrically coupled to a first terminal of the second capacitor by a first switch; and a second switch configured to electrically couple the first terminal of the second capacitor to a second terminal of the first capacitor.

An RF signal generation device includes an RF signal generation unit 102 that pulse-modulates a prescribed signal to generate an output signal in which four or more-level discrete output levels appear and that a lowest level and any other level appear alternately; a code converter 91 that converts the output signal from the RF signal generation unit 102 into an RF signal in which a smaller number of levels than the number of levels in the output signal; a driver unit 203 that converts the RF signal from the code converter 91 into a binary signal comprising plural bits in which bits corresponding to signal levels in the RF signal are significant; and a digital amplifier 303 that outputs a voltage corresponding to levels in the RF signal outputted from the code converter 91, on the basis of an output signal from the driver unit 203.

A digital filter and a method for filtering a pulse density modulation (PDM) signal are presented. The digital filter has a first filter circuit to receive an input signal with input values at successive time steps to provide a filtered input signal with filtered values at successive time steps. The digital filter does not require sample-rate or data format conversions. Also, the digital filter is area and power efficient when implemented in hardware. Optionally, the digital filter has a sigma-delta modulator including the quantiser, the sigma-delta modulator being used to receive the filtered input signal and to process the filtered input signal before and/or after being quantised by the quantiser. This digital filter does not require sample-rate or data format conversions. This digital filter is area and power efficient when implemented in hardware.

A parallel delta sigma modulator architecture is disclosed. The parallel delta sigma modulator architecture includes a signal demultiplexer configured to receive an input signal and to demultiplex the input signal to output a plurality of streams, a plurality of delta sigma modulators executing in parallel, each delta sigma modulator configured to receive a stream from the plurality of streams and to generate a delta sigma modulated output, and a signal multiplexer configured to receive a plurality of delta sigma modulated outputs from the plurality of delta sigma modulators and to multiplex together the plurality of delta sigma modulated outputs into a pulse train.

An incremental analog-to-digital converter (ADC) with high accuracy. The incremental ADC has a delta-sigma modulator, performing delta-sigma modulation on an analog input signal to output a quantized signal, and a digital filter, receiving the quantized signal to generate a digital representation of the analog input signal. A loop filter of the delta-sigma modulator has a preset circuit. In the preset circuit, the output terminal of the loop filter is preset rather than being reset during the reset phase of the incremental ADC.

A modulator includes an input circuit having a sampling capacitor, an integration circuit, a quantizer and a D/A converter having a DAC capacitor. The input circuit takes in an analog input voltage in the sampling capacitor in a sampling period, and transfers a charge to the integration circuit in a holding period. The D/A converter takes in an analog potential, to which selection switches are connected in the sampling period based on a digital output of the quantizer, in the DAC capacitor, and subtracts a charge from the integration circuit in the holding period. At this time, since the input circuit and the D/A converter are set so that the holding periods do not overlap with each other, an error caused by the lowering of a feedback factor is suppressed.

A transmitter and a method capable of transmitting a transmission signal that satisfies a high S/N ratio are provided. A transmitter includes a first signal generation unit including a distributor configured to receive a first N (N: an integer greater than or equal to 3) value digital signal generated from a baseband signal, divide the first N-value digital signal into (N1) binary digital signals, and output the divided (N1) binary digital signals, and a signal amplification unit configured to amplify each of the (N1) binary digital signals and output a transmission signal obtained by combining the amplified (N1) signals.

Described herein is an improved apparatus for increasing the performance of a modulator, which may function as an ADC. In one embodiment, the modulator comprises a voltage to current converter, a capacitor connected between two outputs of the voltage to current converter to receive a differential input current, and a switch that can switch between connecting each output of the voltage to current converter to ground while disconnecting the other output of the voltage to current converter. In this embodiment, the modulator has no common mode control loop, and no reference current. This results in decreased complexity, i.e., fewer components, as well as reduced noise.

A Sigma-Delta analog to digital converter (ADC) is described. The Sigma-Delta ADC includes a series arrangement of a gain tracker, a first discrete-time integrator stage and a quantizer between an ADC input and an ADC output. The Sigma-Delta ADC includes a digital to analog converter (DAC) having a DAC input and a DAC output connected to the gain tracker. The Sigma-Delta analog to digital converter includes a controller having a control input connected to the quantizer output. The controller provides a digital input to the DAC input and provides a gain control signal to the gain tracker.