Temperature-Compensated Power Detector for Closed-Loop RF Output Control
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Solution Overview
Problem
Power detectors connected to intermediate stages of power amplifiers fail to accurately measure actual output power due to temperature variations and antenna mismatch, leading to inaccurate power readings.
Innovation Solution
A power detector circuit with temperature compensation, comprising a detection circuit that generates a power control voltage to offset temperature characteristics of the received RF signal, and a bias circuit that adjusts bias signals to maintain accurate power measurement, even when connected interstage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the power detector is connected to the output of the power amplifier, then the detected power is the actual output power, but the measurement is influenced by antenna mismatch
Solution Approach 1:
The patent introduces an intermediate connection point between the power amplifier and the power detector, using a coupling network as a mediator. This allows the detector to measure power without being directly exposed to antenna mismatch effects, while still obtaining accurate power information through the intermediate measurement point.
Solution Approach 2:
The patent segments the power measurement system into distinct functional blocks: the power amplifier stage, the intermediate coupling network, and the power detector stage. This segmentation allows the detector to be isolated from antenna mismatch while maintaining measurement accuracy through the structured intermediate connection.
2Object-affected harmful factors
If the power detector is connected to an intermediate stage of the power amplifier, then the influence from antenna mismatch is avoided, but the detected power is not the actual output power
Solution Approach 1:
The patent implements a feedback mechanism where the power detector measures intermediate power, and this measurement is fed back through a control circuit that calculates and applies the necessary compensation to determine the actual output power. This feedback loop ensures accurate power measurement despite the intermediate connection point.
Solution Approach 2:
The patent changes the measurement parameter from direct output power to intermediate stage power, and then applies parameter transformation through temperature compensation and calibration factors to derive the actual output power. This parameter change approach allows avoidance of antenna mismatch while maintaining measurement accuracy.
3Device complexity
If temperature compensation is not applied, then the device complexity is reduced, but the power measurement accuracy varies with temperature
Solution Approach 1:
The patent applies temperature compensation by introducing temperature-dependent parameter adjustments to the power measurement circuit. Compensation factors or calibration parameters are modified based on temperature conditions, ensuring accurate power measurement across varying temperatures while adding minimal circuit complexity.
Data Source
AI summary
An amplifier circuit comprises a detection power input circuit for receiving an RF signal, and a bias circuit that includes an output for generating a bias signal in response to a reference control voltage. The power detector further comprises a detection circuit for generating a power control voltage having a voltage characteristic that offsets temperature characteristics of the received RF signal. The amplifier circuit further comprises a power amplifier coupled to the bias circuit. The power amplifier includes a driver stage providing the RF signal. The detection circuit compensates temperature variation of the inputted detection voltage of the received RF signal.