Abstract: A signal amplifying circuit and associated methods and apparatuses, the circuit comprising: a signal path extending from an input terminal to an output terminal, a gain controller arranged to control the gain applied along the signal path in response to a control signal; an output stage within the signal path for generating the output signal, the output stage having a gain that is substantially independent of its supply voltage, and a variable voltage power supply comprising a charge pump for providing positive and negative output voltages, the charge pump comprising a network of switches that is operable in a number of different states and a controller for operating the switches in a sequence of the states so as to generate positive and negative output voltages together spanning a voltage approximately equal to the input voltage.

Abstract: A signal amplifying circuit and associated methods and apparatuses, the circuit comprising: a signal path extending from an input terminal to an output terminal, a gain controller arranged to control the gain applied along the signal path in response to a control signal; an output stage within the signal path for generating the output signal, the output stage having a gain that is substantially independent of its supply voltage, and a variable voltage power supply comprising a charge pump for providing positive and negative output voltages, the charge pump comprising a network of switches that is operable in a number of different states and a controller for operating the switches in a sequence of the states so as to generate positive and negative output voltages together spanning a voltage approximately equal to the input voltage.

Abstract: A signal amplifying circuit and associated methods and apparatuses, the circuit comprising: a signal path extending from an input terminal to an output terminal, a gain controller arranged to control the gain applied along the signal path in response to a control signal; an output stage within the signal path for generating the output signal, the output stage having a gain that is substantially independent of its supply voltage, and a variable voltage power supply comprising a charge pump for providing positive and negative output voltages, the charge pump comprising a network of switches that is operable in a number of different states and a controller for operating the switches in a sequence of the states so as to generate positive and negative output voltages together spanning a voltage approximately equal to the input voltage.

Abstract: A signal amplifying circuit and associated methods and apparatuses, the circuit comprising: a signal path extending from an input terminal to an output terminal, a gain controller arranged to control the gain applied along the signal path in response to a control signal; an output stage within the signal path for generating the output signal, the output stage having a gain that is substantially independent of its supply voltage, and a variable voltage power supply comprising a charge pump for providing positive and negative output voltages, the charge pump comprising a network of switches that is operable in a number of different states and a controller for operating the switches in a sequence of the states so as to generate positive and negative output voltages together spanning a voltage approximately equal to the input voltage.

Abstract: A signal amplifying circuit and associated methods and apparatuses, the circuit comprising: a signal path extending from an input terminal to an output terminal, a gain controller arranged to control the gain applied along the signal path in response to a control signal; an output stage within the signal path for generating the output signal, the output stage having a gain that is substantially independent of its supply voltage, and a variable voltage power supply comprising a charge pump for providing positive and negative output voltages, the charge pump comprising a network of switches that is operable in a number of different states and a controller for operating the switches in a sequence of the states so as to generate positive and negative output voltages together spanning a voltage approximately equal to the input voltage.

Abstract: A signal amplifying circuit and associated methods and apparatuses, the circuit comprising: a signal path extending from an input terminal to an output terminal, a gain controller arranged to control the gain applied along the signal path in response to a control signal; an output stage within the signal path for generating the output signal, the output stage having a gain that is substantially independent of its supply voltage, and a variable voltage power supply comprising a charge pump for providing positive and negative output voltages, the charge pump comprising a network of switches that is operable in a number of different states and a controller for operating the switches in a sequence of the states so as to generate positive and negative output voltages together spanning a voltage approximately equal to the input voltage.

Abstract: A dual mode charge-pump circuit and associated method and apparatuses for providing a plurality of output voltages, using a single flying capacitor, the circuit including a network of switches that is operable in a number of different states and a controller for operating said switches in a sequence of the states so as to generate positive and negative output voltages together spanning a voltage approximately equal to the input voltage and centered on the voltage at the common terminal, in a first mode and positive and negative output voltages each up to substantially the input voltage in a second mode.

Abstract: A charge pump circuit and associated method and apparatuses for providing a plurality of output voltages using a single flying capacitor. The circuit includes a network of switches that are operable in a number of different states and a controller for operating the switches in a sequence of states so as to generate positive and negative output voltages together spanning a voltage approximately equal to the input voltage and centered on the voltage at the common terminal.

Abstract: A signal amplifying circuit and associated methods and apparatuses, the circuit comprising: a signal path extending from an input terminal to an output terminal, a gain controller arranged to control the gain applied along the signal path in response to a control signal; an output stage within the signal path for generating the output signal, the output stage having a gain that is substantially independent of its supply voltage, and a variable voltage power supply comprising a charge pump for providing positive and negative output voltages, the charge pump comprising a network of switches that is operable in a number of different states and a controller for operating the switches in a sequence of the states so as to generate positive and negative output voltages together spanning a voltage approximately equal to the input voltage.

Abstract: A signal amplifying circuit and associated methods and apparatuses, the circuit comprising: a signal path extending from an input terminal to an output terminal, a gain controller arranged to control the gain applied along the signal path in response to a control signal; an output stage within the signal path for generating the output signal, the output stage having a gain that is substantially independent of its supply voltage, and a variable voltage power supply comprising a charge pump for providing positive and negative output voltages, the charge pump comprising a network of switches that is operable in a number of different states and a controller for operating the switches in a sequence of the states so as to generate positive and negative output voltages together spanning a voltage approximately equal to the input voltage.

Abstract: An electronic audio amplifier circuit, operable in two modes and a battery powered portable audio apparatus incorporating the circuit; and associated apparatuses and methods. When in the first mode the audio apparatus is designed for the direct driving of headphones or a speaker. When in the second mode the audio apparatus is designed to drive a line input of an external amplifying apparatus with a signal that having a higher voltage amplitude for a given signal content than when driving headphone or a speaker. The circuit has common output stage circuitry for use in both modes, and a dual mode power supply circuit, ideally a charge pump circuit, for supplying the output stage in the first mode with a lower supply voltage than in the second mode.

Abstract: A charge pump circuit and associated method and apparatuses for providing a plurality of output voltages using a single flying capacitor. The circuit includes a network of switches that are operable in a number of different states and a controller for operating the switches in a sequence of states so as to generate positive and negative output voltages together spanning a voltage approximately equal to the input voltage and centered on the voltage at the common terminal.

Abstract: A dual mode charge-pump circuit and associated method and apparatuses for providing a plurality of output voltages, using a single flying capacitor, the circuit including a network of switches that is operable in a number of different states and a controller for operating said switches in a sequence of the states so as to generate positive and negative output voltages together spanning a voltage approximately equal to the input voltage and centered on the voltage at the common terminal, in a first mode and positive and negative output voltages each up to substantially the input voltage in a second mode.

Abstract: This invention is generally concerned with digital-to-analogue converters and more particularly relates to techniques for reducing signal dependent loading of reference voltage sources used by these converters. A differential switched capacitor digital-to-analogue (DAC) circuit (500) comprises first and second differential signal circuit portions (500a,b) for providing respective positive and negative signal outputs with respect to a reference level, and has first and second reference voltage inputs (112,114) for receiving respective positive and negative references. Each of said first and second circuit portions comprises an amplifier (102a,b) with a feedback capacitor (104a,b), a second capacitor (106a,b), and a switch (108a,b, 110a,b) to switchably couple said second capacitor to a selected one of said reference voltage inputs to charge the second capacitor and to said feedback capacitor to share charge with the feedback capacitor.

Abstract: The present invention relates to a signal interface format for communicating or transferring PCM and DSD digital audio signals particularly, although not exclusively, between chips within digital audio equipment such as CD and DVD players and recorders. The present invention provides a method of and apparatus for interfacing between components of a system or between systems, which accommodates both PCM and DSD digital audio signals. The interface for caring these signals comprises a number of dedicated interface channels, at least one (DATA) dedicated for data transmission where the source or audio data is in PCM or DSD format, and three channels (BITCLK, MCLK, and LRCLK) dedicated for clock signal transmission. Preferably these four channels are implemented on four conductors between two chips, each chip comprising four corresponding input/output pins. Each dedicated DATA interface channel preferably has two source data channels multiplexed onto it.

Abstract: Audio transient suppression circuit (300) has two modes, a first, for example active mode in which the circuit operates to provide an audio signal output and a second, for example standby mode in which said audio signal output is suppressed. The circuit comprises at least one active signal processing stage having an output node (128), the output node having a dc signal path to a first dc voltage (104), said dc signal path including at least one first resistive element (122, 124). The circuit further comprises an output signal transient suppresser, said transient suppresser comprising a second resistive element (304) switchably connected (302) between a second dc voltage (102) and said output node. The second resistive element has a resistance selected such that when said second resistive element is connected the voltage on said output node in said second mode is substantially equal to a quiescent voltage on said output node in said first mode.