Programmable Amplifier Input Impedance for Reflection Control
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Solution Overview
Problem
Amplifier circuits face performance degradation due to impedance mismatches between the amplifier and the input signal source or transmission line, leading to signal reflections and reduced bandwidth.
Innovation Solution
An amplifier system with a programmable input impedance stage comprising transconductance stages that can be selectively activated to match the input impedance with the transmission line, using a bias voltage and impedance selection signal to adjust the impedance at the amplifier input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the input impedance of the amplifier is fixed, then the device complexity is reduced, but the adaptability to different transmission line impedances deteriorates
Solution Approach 1:
The patent implements a programmable input impedance stage that can dynamically adjust the input impedance of the amplifier by selectively activating different transconductance stages based on the impedance of the transmission line. This dynamic adjustment capability allows the amplifier to adapt to various transmission line impedances (e.g., 50 ohms, 75 ohms) without requiring multiple fixed-impedance amplifier circuits, thereby resolving the contradiction between device complexity and adaptability.
2Reliability
If the input impedance is matched to the transmission line, then signal reflections are reduced and bandwidth is improved, but the device complexity increases due to the programmable impedance stage
Solution Approach 1:
The patent divides the input impedance adjustment function into multiple discrete transconductance stages, where each stage corresponds to a specific impedance value. By segmenting the impedance adjustment into separate controllable stages, the system can achieve precise impedance matching to reduce signal reflections and improve bandwidth, while the modular structure allows for efficient implementation that minimizes overall circuit complexity.
3Adaptability or versatility
If multiple transconductance stages are used for impedance adjustment, then the adaptability to different impedances is improved, but the device complexity and power consumption increase
Solution Approach 1:
The patent employs multiple transconductance stages with different transconductance values, but not all stages need to be activated simultaneously. The system can achieve the required impedance adjustment range by selectively activating only the necessary subset of stages based on the specific transmission line impedance, thereby reducing the effective complexity and power consumption while maintaining full adaptability across the required impedance range.
Data Source
AI summary
One embodiment of the invention includes an amplifier system. The amplifier system comprises an amplifier stage configured to receive an input signal at an amplifier input and to provide an amplified output signal. The amplifier system also comprises a programmable input impedance stage comprising a plurality of transconductance stages. At least one of the plurality of transconductance stages can be selectively activated based on a selection signal, the at least one of the activated transconductance stages providing current through the amplifier input that adjusts an impedance associated with the amplifier input based on the amplified output signal.