AC-Coupled Feedback Amplifier Circuit to Prevent Output Saturation
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Solution Overview
Problem
Existing amplifier circuits amplify both the target frequency component and other frequency components, leading to potential output saturation when increasing gain.
Innovation Solution
The amplifier circuit employs first and second feedback units and a coupling unit to independently adjust gain and frequency characteristics, with the coupling unit AC coupling the second feedback unit to the operational amplifier's inverting input terminal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the gain of the amplifier circuit is increased to amplify the target frequency component, then the amplification capability is improved, but the output saturation occurs due to amplification of other frequency components
Solution Approach 1:
The feedback circuit is segmented into two independent feedback paths: a first feedback path that provides frequency-selective feedback for the target frequency component, and a second feedback path that provides frequency-independent feedback for other frequency components. This segmentation allows independent control of gain for different frequency ranges, enabling high gain for the target frequency while maintaining stability for other frequencies to prevent output saturation.
2Power
If the gain is increased for the target frequency, then the signal amplification is improved, but the other frequency components are also amplified causing distortion
Solution Approach 1:
Different feedback paths are assigned different frequency-selective characteristics: the first feedback path is designed with frequency selectivity to provide appropriate feedback only for the target frequency component, while the second feedback path provides feedback for other frequency components. This local quality differentiation ensures that each frequency component receives appropriate gain control, amplifying the target frequency while suppressing distortion of other frequencies.
3Device complexity
If a single feedback circuit is used to control gain, then the circuit complexity is reduced, but the independent adjustment of gain and frequency characteristic becomes difficult
Solution Approach 1:
The feedback circuit is divided into two separate feedback paths with distinct functions: the first feedback path controls the gain for the target frequency component using frequency-selective elements, while the second feedback path controls the gain for other frequency components. This segmentation enables independent adjustment of gain and frequency characteristics without significantly increasing overall circuit complexity, as each path can be designed with standard circuit elements.
Data Source
AI summary
An amplifier circuit includes an operational amplifier to amplify an input signal input to a non-inverting input terminal, first and second feedback units to feed back an output signal output from the operational amplifier to an inverting input terminal of the operational amplifier, and a coupling unit to AC couple the second feedback unit and the inverting input terminal. The first feedback unit is to, together with the coupling unit, as a frequency of the output signal of the operational amplifier is increased, reduce an electric potential to be applied to the inverting input terminal with respect to the output signal. At the same time, the second feedback unit is to generate a predetermined electric potential lower than an electric potential of the output signal, the second feedback unit being configured to apply a predetermined electric potential to the inverting input terminal via the coupling unit.