Parallel-Path Signal Amplifier for Continuous Gain Switching
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Solution Overview
Problem
Existing signal amplifier devices face challenges in smoothly and continuously switching between high gain and high linearity modes due to short-circuit issues and signal cancellation, making it difficult to maintain output signal continuity.
Innovation Solution
A signal amplifier device with a main path and sub path amplifier circuit configuration, using a common-gate transistor and a sub path amplifier circuit with lower gain, allowing continuous gain control without steep changes, and including bias elements and attenuators to manage signal strength and noise performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bypass path operation is used to achieve high linearity mode, then distortion is suppressed for high signal strength, but short-circuit occurs in the input/output terminals of the amplification path making it difficult to operate both paths simultaneously
Solution Approach 1:
An isolation transistor (third transistor) is introduced as an intermediary component between the bypass path and the amplification path. This transistor acts as a switch that electrically isolates the bypass path from the amplification path when both need to operate simultaneously, preventing the short-circuit issue while enabling coordinated operation of both paths for smooth gain transition.
2Reliability
If amplification path alone is used for high gain mode, then noise characteristics are improved for low signal strength, but gain switching causes steep changes making it difficult to maintain continuous output signal
Solution Approach 1:
The patent merges the amplification path and bypass path into a unified system where both paths can operate simultaneously under controlled conditions. By combining the high-gain amplification path with the low-gain bypass path and using the isolation transistor to manage their interaction, the system achieves smooth gain transitions without steep changes, maintaining continuous and stable output signals across different signal strength conditions.
3Ease of operation
If main path and sub path are switched discontinuously, then gain control is simplified, but output signal components cannot be smoothly transitioned leading to gain discontinuity
Solution Approach 1:
The patent implements dynamic control of the isolation transistor's conductivity based on the operating mode requirements. The transistor's conductivity is adjusted continuously or in controlled steps to enable smooth transition between different gain configurations, allowing the system to adapt dynamically between amplification-path-dominant mode, bypass-path-dominant mode, and simultaneous operation mode, thereby maintaining gain stability while preserving control simplicity.
Data Source
AI summary
A signal amplifier device is provided to ensure the continuity of the gain of an amplifier. The signal amplifier device includes a main path and a sub path connected in parallel to the main path. A main path first amplifier circuit amplifies an input signal on the main path. A main path second amplifier circuit includes a common-gate transistor connected in series with an output of the main path first amplifier circuit without sharing a DC current. On the main sub path, the sub path amplifier circuit amplifies the input signal by using a gain lower than the maximum gain in the main path.