The invention provides a sigma-delta modulator (SDM) and associated system improving spectrum efficiency of wired interconnection. The SDM may comprise a main circuit for transferring an aggregated signal by a signal transfer function, and a noise shaping circuit for shaping noise away from a low-pass band by a modified noise transfer function. A frequency response of the modified noise transfer function may have a notch at a passband, and the passband may not overlap with the low-pass band.

A bitstream converter for converting a 1-bit pulse density modulated (PDM) bitstream signal into an analog audio signal, the bitstream converter comprising: a processor configured to process the 1-bit PDM bitstream signal using a return to zero clock having a frequency higher than a sampling frequency of the 1-bit PDM bitstream signal to output a corresponding 1-bit return to zero signal, wherein the processor is configured to process the 1-bit PDM signal to ensure a portion of each bit of the 1-bit PDM bitstream signal is zero for a duration which is based on the frequency of the return to zero clock; and signal processing means configured to extract the analog audio signal from the 1-bit return to zero signal by filtering the 1-bit return to zero signal.

An optical network includes a transmitting portion configured to (i) encode an input digitized sequence of data samples into a quantized sequence of data samples having a first number of digits per sample, (ii) map the quantized sequence of data samples into a compressed sequence of data samples having a second number of digits per sample, the second number being lower than the first number, and (iii) modulate the compressed sequence of data samples and transmit the modulated sequence over a digital optical link. The optical network further includes a receiving portion configured to (i) receive and demodulate the modulated sequence from the digital optical link, (ii) map the demodulated sequence from the second number of digits per sample into a decompressed sequence having the first number of digits per sample, and (iii) decode the decompressed sequence.

A method and apparatus for implementing FIR filters in a processor includes a plurality of execution units executing instructions of an instruction set. The execution units include a number of FIR filter circuits, each of which is associated with a corresponding one of a number FIR filter instructions. Furthermore, each of the FIR filter circuits is and dedicated exclusively to executing its corresponding one of the FIR filter instructions. Each FIR filter execution unit receives input data and provides filtered output data.

The invention provides a sigma-delta modulator (SDM) and associated system improving spectrum efficiency of wired interconnection. The SDM may comprise a main circuit for transferring an aggregated signal by a signal transfer function, and a noise shaping circuit for shaping noise away from a low-pass band by a modified noise transfer function. A frequency response of the modified noise transfer function may have a notch at a passband, and the passband may not overlap with the low-pass band.

A signal modulation device comprising: an input for receiving a complex input signal (106) comprising an in-phase component signal and a quadrature-phase component signal, a sigma-delta modulator (110) for modulating the complex input signal at an oversampling clock rate (F1) into an intermediary signal (112), a numerical oscillator (60) for generating a phase signal (61) oscillating at a selected carrier frequency (FC), wherein the phase signal takes a finite number of quantized states, and a symbol mapping table (114) comprising a predefined quantized symbol for each quantized complex state of the intermediary signal and each quantized state of the phase signal, and operates at each oversampling clock period (F1) to select a quantized symbol (116) as a function of a current quantized complex state of the intermediary signal (112) and a current quantized state of the phase signal (61).

A digital-to-analog converter (DAC) for an audio system in a media device, such as a portable media device or smart phone, may be operated to turn off portions of the DAC to reduce power consumption. Segments of a segment-able DAC may be powered off when the output level of the DAC is lower than the full scale output of the DAC. For example, DAC elements within a finite impulse response (FIR) DAC may be turned off when a desired output level can be obtained with less than all DAC elements of the FIR DAC.

A sigma-delta modulator. The signal-delta modulator includes: an integrator having an instrumentation amplifier designed to receive an input signal to be modulated at a first input and to receive a feedback signal at a second input, wherein the integrator is designed to generate an integrator signal using the input signal and the feedback signal; a quantizer, which is designed to generate a quantizer signal in accordance with the integrator signal; a first FIR digital-to-analog converter, which is designed to generate the feedback signal in accordance with the quantizer signal; a first compensation device, which is designed to compensate for an excess loop delay in accordance with the quantizer signal; and a second compensation device, which comprises a second FIR digital-to-analog converter, which is designed to compensate for a clock cycle shift of the feedback signal in accordance with the quantizer signal.

A digital/analog conversion apparatus to convert a digital signal into an analog signal. The digital/analog conversion apparatus can generate a high-quality analog signal, even when elements configuring the digital/analog conversion apparatus have variance, with high resolution and a small circuit size. The data conversion apparatus is provided with a first data converter to reduce the number of bits of an input signal, a second data converter to convert the format of the first output signal, and a third data converter for conversion into a code which corresponds to the history of the output from the second data converter.