Bridge Amplifier Gain Correction for Balanced and Unbalanced Inputs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional amplifier circuits with complementary bridge configurations face gain imbalance issues when handling both symmetrical and asymmetrical input signals, leading to reduced maximum rms output power and increased distortion, particularly with unbalanced input configurations, and require additional control signals or terminals for correction.
Innovation Solution
The introduction of a compensation offset current injected at the junction node between the inputs of the amplifier circuit, generated by voltage-to-current converters or a buffer circuit, balances the gains of the amplifiers, allowing for balanced output signals without external control signals or additional terminals, effectively correcting gain imbalance and suppressing common mode signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a complementary amplifier stage with unbalanced input configuration is used, then the circuit complexity is reduced, but gain imbalance occurs between the upper and lower amplifiers leading to reduced maximum output power
Solution Approach 1:
The patent applies asymmetry by introducing a compensation offset current specifically to the upper amplifier's input terminal. This asymmetric compensation approach counteracts the inherent gain imbalance in the unbalanced input configuration, allowing the upper amplifier's gain to be adjusted to match the lower amplifier's gain without changing the overall unbalanced structure of the amplifier stage.
Solution Approach 2:
The patent changes the electrical parameter (input current) by injecting a compensation offset current into the upper amplifier's input terminal. This parameter change adjusts the effective gain of the upper amplifier to match the lower amplifier, thereby achieving gain balance while maintaining the unbalanced input configuration's simplicity.
2Manufacturing precision
If gain correction circuits with control inputs are added, then gain imbalance is corrected, but the device complexity and number of terminals increase
Solution Approach 1:
The patent extracts the essential function of gain correction by isolating the compensation offset current generation and injection to a single input terminal (the upper amplifier's input). This extraction eliminates the need for complex control circuits and additional terminals, achieving gain balance through a minimal intervention approach.
Solution Approach 2:
The compensation offset current is generated and injected automatically to balance the gains of the upper and lower amplifiers without requiring external control signals or additional terminals. The system self-corrects the gain imbalance internally, eliminating the need for external gain correction circuits.
3Power
If the upper amplifier's gain is increased to match the lower amplifier, then maximum output power is improved, but the upper amplifier clips first causing distortion
Solution Approach 1:
The patent applies preliminary anti-action by injecting a compensation offset current that preemptively adjusts the upper amplifier's gain to match the lower amplifier's gain. This prevents the upper amplifier from clipping first, thereby eliminating distortion before it occurs and enabling the amplifier to deliver maximum output power without distortion.
Data Source
AI summary
The present invention relates to an amplifier circuit and system, and to a method of compensating a gain imbalance generated in a complementary amplifier stage with first and second amplifier means (22, 24) in a bridge configuration. A compensation offset current is generated in response to the values of input signals supplied to respective inputs of said first and second amplifier means, and the compensation offset current is injected to a junction node between the inputs of the first and second amplifier means (22, 24). Thereby, it can be ensured that the gain of the first and second amplifier means does not depend on the kind of input signals, i.e. balanced or unbalanced input signals. An automatic gain correction can thus be achieved and the requirement of additional control signals or control terminals for selection of gain control circuits depending on the kind of input source or input configuration of the amplifier circuit can be dropped.