Monolithic class d amplifier

Abstract

A monolithic 1.75 is mounted in a speaker cabinet 1.71 to drive the voice coil 1.74 of the speaker 1.70. The monolithic integrated circuit may be a class D amplifier 1.10, and is at least a half-bridge or full bridge power MOSFET device. Structures and process for forming the mos switching devices 2.20 of the bridge driver circuits are disclosed. Also disclosed is the N+ buried layer 4.14 of the QVDMOS transistors 4.43 of the bridge circuits.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This invention is a continuation of U.S. patent application Ser. No. 10 / 738,590, filed Dec. 15, 2003, which is a continuation of U.S. patent application Ser. No. 09 / 392,806, filed Sep. 9, 1999, which is a divisional of U.S. patent application Ser. No. 08 / 973,769, filed Dec. 11, 1997, which claims the priority of International Application No. PCT / US96 / 08826, filed Jun. 5, 1996, all of which are incorporated herein by reference.INTRODUCTION Audio Amplifiers [0002] A convention push-pull (class AB) linear amplifier (FIG. 1A) modulates load power by continuously varying conduction through its pass elements during most, if not all, of the conduction cycle. Q.sub.1 conducts during the positive half-cycle, and Q.sub.2 conducts during the negative. During each half-cycle, the conducting transistor operates in its linear region. The transistor must supply the required current to the load while reducing the voltage between the supply and the loa...

AI Technical Summary

Benefits of technology

"The invention is a monolithic audio amplifier that can handle low voltage audio signals and provide power to a speaker. The amplifier includes a conditioning circuit, a bridge driver circuit, and a bridge circuit. The conditioning circuit generates a series of pulses that act as conditioning pulses for the class D amplifier. The bridge driver circuit contains MOS switch transistors that drive one or more power MOSFETs, which in turn drive the speaker. The amplifier is controlled by a control circuit that monitors the temperature, voltage, and current of the bridge circuit and can shut down the MOSFETs if predetermined limits are exceeded. The invention also contemplates separate integrated circuits for the conditioning circuit, bridge drivers, and QVDMOS bridges, as well as an active speaker with a QVDMOS bridge circuit attached to it. The invention solves the problem of start-up thumps by integrating a control loop integrator or a PWM comparator into the amplifier."

Problems solved by technology

Likewise, further logic circuitry monitors the operating voltage of the power QVDMOS devices and inhibits their operation if there is insufficient voltage available.

Should that occur, the two transistors would be shorted across the load and would rapidly destroy themselves.

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