Doherty Amplifier Control Circuit for Noise-Resistant Peak Biasing
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Solution Overview
Problem
In Doherty amplifier circuits, time delays or noise errors in collector bias voltage can cause the peak amplifier to be activated unnecessarily, leading to increased power consumption and distortion of the radio frequency output signal.
Innovation Solution
A Doherty amplifier circuit with a control circuit that includes a first variable bandpass characteristic circuit and a detector, which adjusts the bias of the peak amplifier based on the detection result, thereby controlling the bandpass characteristic according to the supply voltage and input power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the peak amplifier is activated based on collector bias voltage, then the radio frequency output signal can be amplified, but time delays or noise errors can cause unnecessary activation leading to increased power consumption
Solution Approach 1:
A control circuit is introduced as an intermediary between the collector bias voltage and the peak amplifier activation. The control circuit processes the bias voltage signal through filtering and threshold comparison to determine accurate activation timing, preventing premature or unnecessary peak amplifier activation while maintaining proper amplification capability
Solution Approach 2:
The control circuit monitors the collector bias voltage and provides feedback control to the peak amplifier activation. By continuously comparing the processed bias voltage against threshold values and adjusting activation timing accordingly, the system achieves accurate power amplifier switching that reduces unnecessary activation and power consumption
2Power
If the peak amplifier is activated based on collector bias voltage, then the radio frequency output signal can be amplified, but noise errors can cause activation timing shifts leading to signal distortion
Solution Approach 1:
The control circuit acts as an intermediary that filters and processes the collector bias voltage signal before using it to control peak amplifier activation. This intermediary processing removes noise errors and timing shifts, ensuring reliable activation timing that maintains signal quality while enabling proper amplification
Solution Approach 2:
The control circuit applies filtering and threshold comparison in advance of the peak amplifier activation decision. This beforehand processing cushions against noise errors and timing variations in the collector bias voltage, preventing distortion before it can occur in the output signal
Data Source
AI summary
A Doherty amplifier circuit includes a carrier amplifier that amplifies a radio frequency signal; a peak amplifier that amplifies the radio frequency signal; and a control circuit including a first variable bandpass characteristic circuit configured such that a bandpass characteristic for passing the radio frequency signal is variable according to a supply voltage and a detector that detects the radio frequency signal passing through the first variable bandpass characteristic circuit. The control circuit controls the bias of the peak amplifier according to a detection result of the detector.