Multi-Feedback Amplifier for High-Frequency Stability Control
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Solution Overview
Problem
Conventional feedback amplifiers experience unstable amplification characteristics in high frequency ranges (above several tens of GHz) as the inductance value loaded in the drain terminal of the transistor increases.
Innovation Solution
A feedback amplifier configuration that includes an amplification transistor, a first feedback circuit for negative feedback between the control and second terminals, a second feedback circuit for positive feedback between the control and second terminals, and a third feedback circuit connected in series to the first and in parallel to the second feedback circuit, which adjusts the stability factor in high frequency ranges outside the used frequency band by decreasing the absolute value of impedance with increasing frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the inductance value loaded in the drain terminal of the transistor is increased, then the gain in high frequency range is improved, but the amplification characteristic becomes unstable in high frequency range
Solution Approach 1:
The feedback mechanism is segmented into multiple independent feedback circuits (first feedback circuit for negative feedback, second feedback circuit for positive feedback, third feedback circuit for stability adjustment) rather than using a single inductance element. This segmentation allows each circuit to perform its specific function independently, resolving the contradiction between gain improvement and stability maintenance in high frequency range.
Solution Approach 2:
The invention changes the feedback mechanism from a passive inductance-based approach to an active feedback circuit approach with controllable parameters. The feedback circuits can dynamically adjust their characteristics based on frequency, allowing the system to maintain stability while providing gain enhancement in the high frequency range through parameter optimization rather than fixed inductance values.
2Reliability
If multiple feedback circuits are added to improve stability and gain characteristics, then the amplification performance is improved, but the device complexity increases
Solution Approach 1:
The feedback circuits are designed to perform multiple functions: the first feedback circuit provides negative feedback for basic stability, the second feedback circuit provides positive feedback for gain enhancement, and the third feedback circuit adjusts stability factor across different frequency ranges. This multi-functionality reduces the need for separate dedicated circuits for each function, thereby managing complexity while achieving comprehensive performance improvement.
Solution Approach 2:
The invention employs a hierarchical feedback structure where multiple feedback circuits work together in a coordinated manner. The feedback signals from different circuits interact to simultaneously achieve stability and gain objectives, using the feedback principle itself to manage the complexity introduced by multiple circuits through self-regulation and interactive control.
Data Source
AI summary
Disclosed is a feedback amplifier including: an amplification transistor having a source terminal grounded; a first feedback circuit to provide negative feedback between the gate and drain terminals of the amplification transistor; a second feedback circuit to provide positive feedback between the gate and drain terminals via the first feedback circuit; and a third feedback circuit to adjust the stability factor of the feedback amplifier in a high frequency range outside a used frequency band.