Abrégé

This application relates to methods and apparatus for transfer of multiple digital data streams, especially of digital audio data over a single communications link such as a single wire. The application describes audio interface circuitry comprising a pulse- length-modulation(PLM) modulator (204). The PLM is responsive to a plurality of data streams (PDM-R, PDM-L), to generate a seriesof data pulses (PLM)with a single data pulse having a rising and falling edge in each of a plurality of transfer periods defined by a first clock signal (TCLK). The timing of the rising and falling edgeof each data pulse is dependent upon on a combination of the then current data samples from the plurality of data streams. The duration and position of the data pulse in the transfer window in effect defines a data symbol encoding the data. Circuitry for receiving and extracting the data is also disclosed. An interface receives the stream of data pulses (PLM) and data extraction circuitry (202) samplesthe data pulseto determine which of the possible data symbols the pulse representsand determines a data value for at least one received data stream.

Classes IPC  ?

• H04L 25/49 - Circuits d'émission; Circuits de réception à au moins trois niveaux d'amplitude

Abrégé

An amplifier circuit comprises an input, for receiving an input signal to be amplified; a preamplifier, for amplifying the input signal based on a variable gain; a power amplifier for amplifying the signal output from the preamplifier; and a variable voltage power supply for supplying one or more supply voltages to the power amplifier. The supply voltages are adjusted based on the variable gain or the input digital signal. According to other aspects of the invention, a power supply of an amplifier circuit is clocked using a clock signal, whereby the clock signal has a frequency that varies in accordance with a volume signal or an input signal.

Classes IPC  ?

• H03F 1/02 - Modifications des amplificateurs pour augmenter leur rendement, p.ex. étages classe A à pente glissante, utilisation d'une oscillation auxiliaire