US 5,631,606 A · Fully differential output CMOS power amplifier

Abstract

A fully differential output CMOS power amplifier suitable to be used in a non-volatile memory mixed mode chip for voice record and playback to drive a very low impedance load such as an 8 ohm speaker from a low voltage power supply. This fully differential CMOS power amplifier utilizes a voltage multiplying technique for the input stage, a level shift/gain stage, and a common mode feedback network. It also utilizes native n-MOS having a threshold voltage VT.apprxeq.0v for the folded cascode differential input, native n-MOS (VT.apprxeq.0v) for the source follower output stage, enhancement n-MOS (VT.apprxeq.0.7 v) for the common source output, and a voltage regulator using p-MOS diode connected devices for simulating a resistor divider to regulate the voltage multiplier output. The amplifier also includes a mechanism for crossover distortion reduction at the output driver stage, and a scheme to set the idle current in the output driver n-MOS transistors.

Claims15

Dependent claims

A differential output CMOS power amplifier for low voltage operation comprising:

a folded cascode differential input stage having native n-MOS devices forming the differential input;
a level shift and gain stage coupled to the differential input stage;
a pair of power output stages coupled to the level shift and gain stage, each power output stage having an output terminal forming one of the differential outputs of the CMOS power amplifier;
a bias generator for providing bias currents to the folded cascode differential input stage, the level shift and gain stage, and the pair of power output stages;
the pair of power output stages having input power terminals for coupling to a low voltage power supply;
the bias generator, the folded cascode differential input stage and the level shift and gain stage having terminals for coupling to a voltage substantially higher than the low voltage power supply.

3 more elements

Dependencies are inferred from the claim text.

Fully differential output CMOS power amplifier

Life of this patent

Fully differential output CMOS power amplifier

Life of this patent

Abstract

Claims15