Parallel-Path Power Amplifier Biasing for Stable RF Phase and Gain
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Solution Overview
Problem
The existing power amplifier technology has unstable phase and gain due to reliance on collector biases for gain adjustments, leading to phase instability in radio-frequency signal output.
Innovation Solution
A power amplifier design with parallel paths and phase shifters, utilizing current-mirror connections and bias circuits to stabilize phase and gain, including transistors and bias circuits connected to establish current-mirror and emitter-follower connections to maintain consistent transistor characteristics and reduce gain variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If gain adjustments are made only by collector biases of first-stage amplifiers, then the amplifier structure is simple, but the phase and gain of the amplifier paths become unstable
Solution Approach 1:
The bias control function is segmented into three independent bias circuits (first, second, and third bias circuits), each controlling different aspects of the amplifier operation. The first bias circuit controls collector biases, the second bias circuit controls base biases of second-stage amplifiers, and the third bias circuit controls emitter biases. This segmentation allows independent optimization of gain and phase stability without interfering with each other.
Solution Approach 2:
Base biases of second-stage amplifiers are introduced as intermediary control parameters between the input signal and the output. By controlling the base biases through the second bias circuit, the patent achieves stable phase and gain characteristics without directly manipulating collector biases alone, thus resolving the instability issue while maintaining structural simplicity.
2Ease of operation
If collector biases are used for gain adjustment, then gain control is achieved, but phase instability occurs in the output signal
Solution Approach 1:
The bias control system is divided into three separate bias circuits with distinct functions. The first bias circuit maintains collector biases for gain control, the second bias circuit stabilizes base biases of second-stage amplifiers to ensure phase stability, and the third bias circuit controls emitter biases. This segmentation allows gain control to be achieved through collector biases while phase stability is maintained through dedicated base bias control.
Solution Approach 2:
Different bias control strategies are applied to different stages of the amplifier. The first bias circuit applies collector bias control where gain adjustment is needed, while the second bias circuit applies base bias control specifically at the second-stage amplifiers where phase stability is critical. This localized application of different bias control qualities resolves the contradiction between gain control and phase stability.
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
The solution effectively stabilizes phase and gain, reducing variations and maintaining consistent amplifier performance even with temperature changes, thereby enhancing the reliability of radio-frequency signal amplification.
Implementation Method 1
the second transistor and the sixth transistor are connected so as to establish a current-mirror connection, and the fourth transistor and the seventh transistor are connected so as to establish a current-mirror connection
Data Source
AI summary
There are included a first amplifier and a second amplifier electrically connected to a stage subsequent to the first amplifier, a third amplifier and a fourth amplifier electrically connected to a stage subsequent to the third amplifier, a phase shifter that makes a phase of a radio-frequency signal passing through a first path different from a phase of a radio-frequency signal passing through a second path, a first bias circuit that supplies a bias to the first amplifier and the third amplifier, a second bias circuit that supplies a bias to the first amplifier and the second amplifier, and a third bias circuit that supplies a bias to the third amplifier and the fourth amplifier. The second amplifier includes a second transistor, the fourth amplifier includes a fourth transistor, the second bias circuit includes a sixth transistor, and the third bias circuit includes a seventh transistor.