Feedback Amplifier Circuit for Phase-Balanced Sinusoid Signals
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Solution Overview
Problem
In RF and microwave applications, mixers like image rejection mixers and I/Q-modulators face performance limitations due to frequency-dependent amplitude and phase balance, which are exacerbated by the need for additional amplifier stages that increase power consumption and circuit size when trying to enhance signal quality.
Innovation Solution
An amplifier circuit with a sequence of at least three transistor amplifiers, where each sequence provides feedback to reduce phase and amplitude errors in sinusoid signals, allowing for increased performance without adding extra amplifier stages or circuit size, by converting phase errors into amplitude errors and using a current-follower configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cascading polyphase filters is used to increase signal quality, then phase and amplitude balance is improved, but power consumption and circuit area increase due to additional amplifier stages
Solution Approach 1:
The patent applies feedback by connecting the output of each transistor amplifier in the first sequence to the input of the corresponding transistor amplifier in the second sequence, creating a feedback loop that automatically corrects phase and amplitude imbalances without requiring additional amplifier stages, thereby improving signal quality while avoiding increased power consumption
Solution Approach 2:
The patent changes the configuration parameters of the existing transistor amplifiers by introducing feedback connections and using current-follower configuration, which transforms the phase errors into amplitude errors that can be corrected by the feedback mechanism, improving signal quality without adding circuit stages
2Measurement precision
If cascading polyphase filters is used to increase signal quality, then phase and amplitude balance is improved, but circuit area increases due to additional amplifier stages
Solution Approach 1:
The feedback connection between the first and second sequences of transistor amplifiers enables automatic correction of phase and amplitude imbalances using existing circuit components, eliminating the need for additional amplifier stages that would increase circuit area
Solution Approach 2:
The transistor amplifiers in the second sequence serve multiple functions: they provide current following for the first sequence amplifiers and simultaneously provide feedback signals for correcting phase and amplitude imbalances, maximizing the utility of existing circuit components without adding area
3Measurement precision
If additional amplifier stages are added to compensate for dampening, then signal quality is improved, but power consumption increases
Solution Approach 1:
The feedback loop continuously monitors the output signals and automatically adjusts the amplification to compensate for dampening effects, maintaining signal quality without requiring additional amplifier stages that would consume more power
Solution Approach 2:
The amplifier circuit performs self-correction of phase and amplitude imbalances through the feedback mechanism, automatically compensating for dampening effects without external intervention or additional power-consuming stages
Data Source
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AI summary
An amplifier circuit (1) for amplifying a plurality of sinusoid signals having a relative phase difference to each other is provided. The amplifier circuit comprises a first sequence (10) of at least three transistor amplifiers (11-14), wherein a first terminal (11a-14a) of each transistor amplifier of the first sequence is configured to receive one respective signal of the plurality sinusoid signals. The amplifier further comprises a second sequence (20) of at least three transistor amplifiers (21-24). A second terminal (21b-24b) of each transistor amplifier of the second sequence is connected to a third terminal (11c-14c) of one respective transistor amplifier of the first sequence. A first terminal (21a-23a) of each transistor amplifier of the second sequence is connected to the third terminal (22c-24c) of a next transistor amplifier (22-24) of the second sequence. The first terminal (24a) of a last transistor amplifier (24) is connected to the third terminal (21c) of a first transistor amplifier (21).