RF Power Amplifier Soft Shutdown for Overvoltage Protection

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Solution Overview

Problem

Existing RF power amplifier modules face thermal breakdown due to varying supply voltages, leading to potential interruption of ongoing activities, as existing overvoltage protection methods either fail to prevent thermal damage or require shutting down the amplifier.

Innovation Solution

A circuit and method that dynamically adjust the control current high limit based on detected supply voltage levels, ensuring a linear decrease above a preset limit, maintaining constant power dissipation and preventing thermal breakdown without interrupting operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If overvoltage protection is implemented using existing methods, then thermal breakdown is prevented, but amplifier operation is interrupted

Engineering Contradiction:

Improvethermal breakdown preventionVSAvoidamplifier operation continuity

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent implements dynamic adjustment of the control current high limit based on detected supply voltage levels. When overvoltage is detected, the control current limit is reduced linearly rather than shutting down completely, allowing the amplifier to continue operating in a protected state while preventing thermal breakdown

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If supply voltage varies without protection, then amplifier can operate flexibly, but thermal damage occurs due to excessive power dissipation

Engineering Contradiction:

Improvesupply voltage variation toleranceVSAvoidthermal damage

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent employs a feedback mechanism where the supply voltage is continuously detected and compared against a preset limit. Based on this feedback, the control current high limit is dynamically adjusted to maintain constant power dissipation, preventing thermal damage while allowing flexible operation across varying supply voltages

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes the control current parameter dynamically based on supply voltage conditions. By adjusting the control current high limit as a linear function of the detected voltage above the preset limit, the system maintains safe power dissipation levels while adapting to varying supply voltage conditions

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10965255B1Overvoltage protection for power amplifier with soft shutdown

Publication Date: 2021.03.30 PSEMI CORP

AI summary

Various methods and circuital arrangements for protection of a power amplifier from over voltage are presented. According to one aspect, a protection circuit coupled to a varying supply voltage of the power amplifier controls a biasing current to the power amplifier to limit a power dissipation through the power amplifier. An overvoltage protection circuit detects a level of the varying supply voltage and decreases the biasing current as a linear function of an increasing supply voltage once the supply voltage reaches a programmable voltage level. A slope of the linear function can be made programmable. Programmability of the voltage level and the slope can be used to control biasing currents to a plurality of power amplifiers operating at different times and having different requirements in terms of voltage limits and thermal breakdown. According to another aspect a voltage to current converter for use in the overvoltage protection circuit is presented.