Variable XCP LMBA for Millimeter-Wave Gain and Linearity
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Solution Overview
Problem
The difference in gain between class-AB and class-C amplifiers in the millimeter-wave frequency band restricts the application of load-modulated balanced amplifiers (LMBA), affecting their linearity and efficiency.
Innovation Solution
An LMBA based on a variable cross-coupled pair (XCP) with an adaptive bias circuit and multiple amplifier modules, including balance and driver amplifiers, and 90-degree differential couplers, which adjusts the load impedance to maintain amplifier gain and linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a class-C amplifier is used in the millimeter-wave frequency band, then power efficiency is improved, but gain is significantly reduced
Solution Approach 1:
The patent combines a class-AB amplifier and a class-C amplifier into a single integrated amplifier system. The class-AB amplifier provides high gain while the class-C amplifier provides high efficiency, and their outputs are combined through a 3-dB coupler to achieve both high gain and high efficiency simultaneously in the millimeter-wave frequency band.
2Use of energy by moving object
If load modulation is implemented by changing the output power ratio between control and balance amplifiers, then power amplifier efficiency is improved, but linearity is seriously affected
Solution Approach 1:
The patent introduces an auxiliary amplifier as an intermediary component that generates a compensation signal to counteract the nonlinearity introduced by load modulation. This compensation signal is combined with the main amplifier output through a 3-dB coupler, effectively canceling out the distortion and improving linearity while maintaining the efficiency benefits of load modulation.
3Use of energy by moving object
If the overall gain is reduced dramatically with an increase of input power, then the class-C amplifier operates efficiently, but amplifier linearity is seriously affected
Solution Approach 1:
The patent implements a feedback mechanism where the auxiliary amplifier monitors the output signal and generates a compensation signal that is fed back to correct the linearity distortion. This feedback loop maintains amplifier linearity across different input power levels while allowing the class-C amplifier to operate efficiently.
Data Source
AI summary
A load-modulated balanced amplifier (LMBA) based on a variable cross-coupled pair (XCP) is provided. The LMBA includes an adaptive bias (ADB) circuit, a first balance terminal amplifier module, a second balance terminal amplifier module, a control terminal amplifier module, a first driver amplifier module, a second driver amplifier module, a third driver amplifier module, a variable XCP, a resistor R5, a resistor R6, a 90-degree differential coupler Q1, a 90-degree differential coupler Q2, and a 90-degree differential coupler Q3.