Impedance Matching Circuit With Feedback Trimming for Switch Linearity
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Solution Overview
Problem
Impedance mismatches in semiconductor devices due to manufacturing variations lead to power consumption inefficiencies and signal distortions in communications systems, which conventional impedance matching circuits fail to fully address.
Innovation Solution
A trimming circuit is implemented with a termination resistor and trimming resistors in parallel, coupled to switches, where the resistance ratio of the switches matches the ratio of the termination and trimming resistors, and the amplifier output is connected back to the negative input through one switch to reduce nonlinearity effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If MOS transistors are used as switches in the trimming circuit, then the circuit can achieve impedance matching and power transfer optimization, but the inherent nonlinear characteristics of the MOS transistors cause signal distortions and degrade linearity
Solution Approach 1:
The trimming circuit is segmented into two parallel paths: one containing the termination resistor with a first switch, and another containing trimming resistors with second switches. This segmentation allows different components to handle different functions - the first switch handles the feedback path while the second switches handle the trimming function, isolating the nonlinear effects.
Solution Approach 2:
The termination resistor serves as an intermediary element that provides a linear reference path. By coupling the amplifier output back to the negative input through the first switch and termination resistor, it creates a linear feedback path that compensates for the nonlinearities introduced by the MOS transistors in the trimming path.
2Ease of manufacture
If trimming resistors are integrated into the circuit board to lower cost, then manufacturing cost is reduced, but impedance matching precision is compromised
Solution Approach 1:
The circuit uses multiple trimming resistors in parallel that can be selectively activated. This allows for fine-grained adjustment of the impedance matching, providing precision comparable to integrated solutions while maintaining the cost benefits of discrete components on a circuit board.
3Reliability
If conventional impedance matching circuits are used, then basic impedance matching is achieved, but they fail to fully address power consumption inefficiencies and signal distortions caused by manufacturing variations
Solution Approach 1:
The trimming circuit uses controllable switches (MOS transistors) that can dynamically adjust the resistance values by selectively connecting or disconnecting trimming resistors. This dynamic adjustment capability allows the circuit to adapt to manufacturing variations and optimize power consumption in real-time, going beyond static conventional impedance matching circuits.
Solution Approach 2:
The circuit implements a feedback mechanism by coupling the amplifier output back to the negative input through the first switch and termination resistor. This feedback loop enables the circuit to automatically compensate for impedance mismatches and optimize power transfer, addressing power consumption inefficiencies that conventional circuits fail to resolve.
Data Source
AI summary
A circuit comprises an amplifier circuit and a trimming circuit. The amplifier circuit includes an operational amplifier. The operational amplifier has a first input configured to receive input signals, and the operational amplifier also has a second input and an amplifier output. One of the first input or the second input is a negative input. The trimming circuit is coupled to the amplifier output. The trimming circuit includes a termination resistor coupled in parallel with at least one trimming resistor. The termination resistor is coupled to a first switch in series, and the trimming resistor is coupled to a second switch in series. The amplifier output is connected back to the negative input through the first switch.