RF Power Amplifier Feedback for Constant Radiated Power
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Solution Overview
Problem
Conventional RF transceiver circuitry fails to maintain constant radiated power and sufficient sensitivity due to antenna impedance mismatches, leading to degraded signal quality and reduced power delivery into space.
Innovation Solution
The RF transceiver architecture incorporates power amplifier circuits that measure antenna reflected power relative to forward power, using an error amplifier signal to adjust the gain of a variable gain amplifier to compensate for mismatches, and includes an antenna alarm circuit to detect gross mismatches or disconnections, ensuring constant radiated power and enhanced receiver sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional power amplifier circuits are designed to operate with 50 Ohm antenna impedance, then optimal power delivery is achieved under ideal conditions, but radiated power becomes non-optimal and signal quality degrades when antenna impedance mismatches occur
Solution Approach 1:
The patent implements a feedback mechanism where the system measures the actual radiated power through a coupler and comparator, compares it with the desired power level, and adjusts the power amplifier output accordingly through a variable gain amplifier to maintain constant radiated power despite antenna impedance variations
Solution Approach 2:
The patent dynamically changes the operating parameters of the power amplifier by adjusting the gain of the variable gain amplifier based on feedback signals, allowing the system to adapt to different antenna impedance conditions and maintain optimal radiated power across varying conditions
2Power
If isolators are introduced between the PA output and antenna connector to maintain constant impedance, then the PA delivers constant power towards the antenna, but the system becomes bulky and expensive with non-ideal performance
Solution Approach 1:
The patent extracts the impedance matching function from the traditional isolator component and implements it through active circuit elements including a coupler, comparator, and variable gain amplifier, thereby eliminating the need for bulky passive isolators while achieving similar power delivery stability
Solution Approach 2:
The patent replaces the mechanical/passive isolator with an active electronic control system that uses electrical feedback and amplification to achieve impedance compensation, substituting a complex passive component with a controllable active circuit
3Power
If load insensitive PA architectures are used to mitigate forward power changes, then forward power remains constant, but radiated power into space remains reduced due to antenna mismatch
Solution Approach 1:
The patent uses feedback to measure actual radiated power through the coupler and adjusts the variable gain amplifier to compensate for power lost to mismatch, ensuring that the power actually radiated into space matches the desired level rather than just maintaining constant forward power
Data Source
AI summary
An RF receiver circuit configuration and design limited by conditions and frequencies to simultaneously provide steady state low-noise signal amplification, frequency down-conversion and image signal rejection. The invention provides combined circuits of an RF transceiver architecture that measure antenna reflected power relative to forward power using the error amplifier signal to adjust the gain of the variable gain amplifier in order to compensate for the mismatch between forward reflected power and forward power at the antenna in order to achieve constant radiated power. The RF receiver circuit may be implemented as one of a CMOS single chip device or as part of an integrated system of CMOS components.