Power Amplifier Bias Timing for Low-Temperature Breakdown Resistance
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Solution Overview
Problem
Existing power amplifying circuits face challenges in maintaining transistor resistance to voltage breakdown at low temperatures and in reducing current consumption.
Innovation Solution
A power amplifying circuit that includes an output transistor, a bias circuit, and a bias control part with a control circuit that increases the bias current or voltage when the ambient temperature is equal to or less than a predetermined threshold value, specifically during time periods preceding increased output from the output transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power source voltage is increased to improve transistor resistance to voltage breakdown at low temperatures, then the transistor's resistance to voltage breakdown is improved, but the current consumption of the power amplifying circuit increases
Solution Approach 1:
The bias control part dynamically adjusts the bias current or voltage based on ambient temperature conditions. When the ambient temperature is equal to or less than a predetermined threshold value, the bias control part increases the bias current or voltage to improve transistor resistance to voltage breakdown. When the ambient temperature is higher than the threshold value, the bias control part maintains the bias current or voltage at normal levels, thereby avoiding unnecessary current consumption while ensuring reliable operation across different temperature conditions.
2Reliability
If the bias current or voltage is increased continuously to maintain transistor performance, then the transistor's resistance to voltage breakdown is improved, but the current consumption increases
Solution Approach 1:
The invention applies different bias conditions to different temperature scenarios. The bias control part selectively increases the bias current or voltage only when the ambient temperature is equal to or less than a predetermined threshold value, rather than continuously increasing it. This localized adjustment ensures that the transistor receives enhanced protection against voltage breakdown only when necessary (at low temperatures), while avoiding excessive current consumption during normal temperature operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enhances the transistor's resistance to voltage breakdown at low temperatures and reduces current consumption by optimizing bias current or voltage levels based on ambient temperature and output demands.
Implementation Method 1
an amount of heat generation of the output transistor increasing with an increase of a current passing therethrough
Implementation Method 2
a bias control part that is connected to the bias circuit part and includes a control circuit that increases the bias current or voltage when an ambient temperature is equal to or less than a predetermined threshold value
Data Source
AI summary
A power amplifying circuit includes an output transistor that amplifies a radio frequency signal and outputs an amplified signal, a bias circuit that supplies a bias current or voltage to the output transistor, and a bias control part connected to the bias circuit and includes a control circuit that increases the bias current or voltage when an ambient temperature is equal to or less than a predetermined value. In consecutive time periods of a first, a second, and a third time period, when output of the output transistor in the third time period is greater than output of the output transistor in the first and the second time period, the bias control part increases the bias current or voltage in the second time period as to become higher than the bias current or voltage of a case where the ambient temperature is higher than the predetermined threshold value.