Self-Regulating Bias Circuit for Stable RF Transistor Bias
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Power amplifiers relying on unregulated power supplies are susceptible to variations in supplied power, leading to unstable quiescent conditions in RF power transistors, which is undesirable and often requires expensive regulated voltage solutions.
Innovation Solution
A self-regulating biasing circuit (SRBC) that uses an impedance network, variance detector, and compensation controller to maintain a stable quiescent current and collector current despite variations in the unregulated supply voltage, eliminating the need for an external voltage regulator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an unregulated power supply is used, then cost is reduced, but stability of quiescent conditions deteriorates
Solution Approach 1:
The biasing circuit automatically compensates for supply voltage variations through self-regulation. The impedance network detects voltage changes and the compensation controller adjusts biasing parameters accordingly, enabling the circuit to maintain stable quiescent conditions without external regulation
Solution Approach 2:
The circuit employs a feedback mechanism where the impedance network monitors supply voltage variations and feeds this information to the compensation controller, which then adjusts the biasing to counteract the detected variations, maintaining stability without requiring regulated power supply
2Stability of the object's composition
If a regulated voltage solution is used, then stability of quiescent conditions is improved, but cost increases
Solution Approach 1:
The biasing circuit performs its own regulation function through self-contained impedance network and compensation controller, eliminating the need for separate regulated power supply components and reducing overall system cost while maintaining stability
Solution Approach 2:
The patent extracts the voltage regulation function from the power supply system and integrates it directly into the biasing circuit through the impedance network and compensation controller, removing the need for external voltage regulator components
3Device complexity
If unregulated power supply is used, then device complexity is reduced, but reliability deteriorates
Solution Approach 1:
The biasing circuit autonomously compensates for power supply variations through its built-in impedance network and compensation controller, maintaining reliable operation without requiring complex external regulation systems
Solution Approach 2:
The feedback mechanism within the biasing circuit continuously monitors and corrects for supply voltage variations, ensuring reliable operation while keeping the overall device complexity low by avoiding external regulator components
Data Source
AI summary
A disclosed self regulating biasing circuit (SRBC) includes an unregulated node that couples to an unregulated power supply that produces a supply voltage. An impedance element of the SRBC carries an unregulated current having a nominal component and a variance component between an unregulated node and a regulated node. A detection circuit connected between the unregulated node and a third node detects a variance component of a supply voltage and generates a detection current based on the variance component. A compensation circuit connected to the third node draws a compensation current, based on the detection current, from the regulated node. The SRBC is designed wherein the compensation current is approximately equal to the variance component of the unregulated current. The regulated node may be connected to a control terminal of a transistor to be biased.