Power Amplifier Bias Current Cutoff for Fast Overcurrent Protection

Solution Overview

Problem

Existing power amplifier circuits face delays and output loss due to the placement of switching circuits on the drain side, which degrades RF characteristics and slows down overcurrent or overvoltage protection.

Innovation Solution

A power amplifier circuit design that includes a detection circuit to identify overcurrent or overvoltage and a draw circuit to directly interrupt the bias current supply, improving the speed of protection functions by stopping amplifier operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a switching circuit is provided on the drain side with respect to the amplifier, then the amplifier can be protected from excess drain current, but time delay occurs and loss (decrease in output) is caused by the resistive component

Engineering Contradiction:

Improveprotection functionVSAvoidoperation speed

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent inverts the conventional protection approach by placing the switching circuit on the source side instead of the drain side, and by drawing bias current to stop amplifier operation rather than disconnecting the amplifier from the power supply. This inversion eliminates the time delay and output loss associated with drain-side switching while maintaining protection functionality.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent implements preliminary action by drawing the bias current to stop the amplifier operation before excess drain current can occur. The detection circuit detects overcurrent or overvoltage conditions and the draw circuit immediately draws the bias current to prevent the harmful effect, rather than waiting for the drain-side switching circuit to react.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If a switching circuit is provided on the drain side with respect to the amplifier, then the amplifier can be protected from excess drain current, but loss (decrease in output) is caused by the resistive component

Engineering Contradiction:

Improveprotection functionVSAvoidoutput loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent inverts the conventional protection approach by placing the switching circuit on the source side instead of the drain side, and by drawing bias current to stop amplifier operation rather than disconnecting the amplifier from the power supply. This inversion eliminates the time delay and output loss associated with drain-side switching while maintaining protection functionality.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent implements preliminary action by drawing the bias current to stop the amplifier operation before excess drain current can occur. The detection circuit detects overcurrent or overvoltage conditions and the draw circuit immediately draws the bias current to prevent the harmful effect, rather than waiting for the drain-side switching circuit to react.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If a switching circuit is provided on the drain side with respect to the amplifier, then the amplifier can be protected from excess drain current, but the RF characteristic is degraded

Engineering Contradiction:

Improveprotection functionVSAvoidRF characteristic

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent inverts the conventional protection approach by placing the switching circuit on the source side instead of the drain side, and by drawing bias current to stop amplifier operation rather than disconnecting the amplifier from the power supply. This inversion eliminates the time delay and output loss associated with drain-side switching while maintaining protection functionality.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS11996809B2Power amplifier circuit

Publication Date: 2024.05.28 MURATA MFG CO LTD

AI summary

There is provided a power amplifier circuit with improved operation speed of the protection function against overcurrent or overvoltage. The power amplifier circuit includes an amplifier configured to amplify a radio frequency signal and output the radio frequency signal, a bias current supply circuit configured to supply a bias current to the amplifier, a detection circuit configured to detect whether the current or voltage of the amplifier is equal to or greater than a predetermined threshold; and a draw circuit configured to, when the detection circuit detects that the current or voltage is equal to or greater than the predetermined threshold, draw at least a part of the bias current supplied to the amplifier.