Improved mechanisms for applying noise-shaped segmentation techniques in a multi-bit DAC are disclosed. Noise-shaped segmentation refers to constructing two or more noise-shaped signals whose sum equals the original digital input signal by splitting each word of the input signal into two or more sub-words and converting each sub-word by a respective sub-word DAC group. Disclosed mechanisms include determining a range of amplitudes of a portion of the input signal over a certain time period, and, when converting digital words of that portion to analog values, limiting the number of sub-word DAC groups which are used for the conversion only to a number that is necessary for generating an analog output corresponding to the portion being evaluated, which number is determined based on the tracked amplitudes and could be smaller than the total number of sub-word DAC groups. Placing unused sub-word DAC groups into a power saving mode reduces power consumption.

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.

An apparatus for dynamic range enhancement (DRE) which receives an input signal and provides a DRE output signal is presented. The apparatus has an error correction circuit to apply an error correction factor to the input signal such that the DRE output signal provided by the apparatus is dependent on the input signal and the error correction factor. The error correction factor is representative of an error generated by the apparatus.

An apparatus for dynamic range enhancement (DRE) which receives an input signal and provides a DRE output signal is presented. The apparatus has an error correction circuit to apply an error correction factor to the input signal such that the DRE output signal provided by the apparatus is dependent on the input signal and the error correction factor. The error correction factor is representative of an error generated by the apparatus.

This application relates to audio circuits, such as audio driving circuits, with improved audio performance. An audio arrangement (200) has an audio circuit (201) with a forward signal path between an input (102) for an input digital audio signal (D.sub.IN) and an output (103) for an output analogue audio signal (A.sub.OUT). The circuit also has a feedback path comprising an analogue-to-digital conversion module (202) for receiving an analogue feedback signal (V.sub.FB) derived from the output analogue audio signal and outputting a corresponding digital feedback signal (D.sub.FB). The analogue-to-digital conversion module (202) has an ADC (108), an analogue gain element (203) configured to apply analogue gain (G.sub.A) to the analogue feedback signal before the ADC and a digital gain element (204) for applying digital gain (G.sub.D) to a signal output from the ADC. A gain controller (205) controls the analogue gain and the digital gain applied based on the input digital audio signal (D.sub.IN).

A X-bit Digital-to-Analog Converter (DAC) circuit includes an effective X/2-bit coarse DAC configured to produce a coarse bitstream (CBS) from a digital input DC.sub.1 using an n.sup.th order Sigma-Delta () modulator, and to provide a coarse current source based on the CBS, wherein X is an even integer and n is an integer; an effective X/2-bit fine DAC configured to produce a fine bitstream (FBS) from a digital input DC.sub.2 using a 1.sup.st order modulator, and to provide a fine current source based on the FBS; and an output configured to form a voltage from the combination of the coarse current source and the fine current source.

Provided, among other things, is an apparatus that converts a signal from one sampling domain to another, and which includes: an input line for accepting an input signal and a processing branch. The processing branch includes a branch input coupled to the input line for inputting data samples that are discrete in time and in value, a quadrature downconverter, a first and second lowpass filter, a first and second polynomial interpolator, and a rotation matrix multiplier that provides a phase rotation. The processing branch generates data samples at a sampling interval that differs from the sampling interval associated with the signal provided to the branch input, e.g., with the difference in the sampling intervals depending on fluctuations in the output period of a local oscillator. Certain embodiments include multiple such processing branches, e.g., operating on different frequency bands of the input signal.

A signal processing circuit includes a filter generating a quantizer input signal from a noise shaping input signal and a quantizer output signal. A quantizer divides the quantizer input signal by a scaling factor to produce a noise shaping output signal and multiplies the noise shaping output signal by the scaling factor to produce the quantizer output signal. Receiver circuitry scales the quantizer output signal by a second scaling factor. A dynamic range optimization circuit compares a current value of the noise shaping input signal to a threshold value, lowers or raises the scaling factor in response to the comparison, and proportionally lowers or raises the scaling factor such that a ratio between the scaling factor and second scaling factor remains substantially constant.

This application relates to audio circuits, such as audio driving circuits, with improved audio performance. An audio arrangement (200) has an audio circuit (201) with a forward signal path between an input (102) for an input digital audio signal (D.sub.IN) and an output (103) for an output analogue audio signal (A.sub.OUT). The circuit also has a feedback path comprising an analogue-to-digital conversion module (202) for receiving an analogue feedback signal (V.sub.FB) derived from the output analogue audio signal and outputting a corresponding digital feedback signal (D.sub.FB). The analogue-to-digital conversion module (202) has an ADC (108), an analogue gain element (203) configured to apply analogue gain (G.sub.A) to the analogue feedback signal before the ADC and a digital gain element (204) for applying digital gain (G.sub.D) to a signal output from the ADC. A gain controller (205) controls the analogue gain and the digital gain applied based on the input digital audio signal (D.sub.IN).

A digital-to-analog converter (DAC) circuit includes a first DAC that produces a first analog output signal based upon a received multi-bit digital signal and upon a received clock. A second DAC that produces a second analog output signal based upon the received multi-bit digital signal and upon the received clock, wherein the first and second DACs are connected in parallel and process the same multi-bit digital signal. In one embodiment, the DACs produce differential signals. A low pass filter connected to receive the first and second analog outputs is configured to sum the first and second analog outputs and to filter the summed first and second analog outputs to produce an ingoing analog signal. An amplifier is connected to receive the ingoing analog signal to produce an amplified ingoing analog signal.