Amplifier Bypass Circuit With Attenuator for Oscillation Suppression

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Solution Overview

Problem

Amplifier circuits with bypass paths experience instability due to feedback issues, leading to oscillation, especially when amplifying high-frequency signals.

Innovation Solution

Incorporating an attenuator between the amplifier and the switch circuit in the bypass path to reduce feedback and stabilize the amplifier circuit, while maintaining a gain of 10 dB or more and attenuation of 0.1 dB or less.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a bypass path is added to the amplifier circuit to handle large input signals, then the amplifier circuit can process large signals without distortion, but feedback occurs in the bypass path causing instability and oscillation

Engineering Contradiction:

Improvesignal handling capabilityVSAvoidcircuit stability

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

An attenuator is introduced as an intermediary component in the bypass path between the amplifier output and the switch circuit. This attenuator reduces the signal level and prevents excessive feedback from occurring in the bypass path, thereby maintaining circuit stability while still allowing large signals to be handled properly.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent utilizes controlled feedback by introducing the attenuator to manage the feedback signal level in the bypass path. By attenuating the feedback signal, the system prevents oscillation while maintaining the ability to handle large input signals through the bypass path.

Inventive Principle:

Principle #23Feedback

2Stability of the object's composition

If the attenuator attenuation is increased to suppress feedback, then circuit stability improves, but signal loss increases

Engineering Contradiction:

Improvecircuit stabilityVSAvoidsignal loss

Core Design Contradiction:

Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The patent applies partial attenuation rather than complete or excessive attenuation. The attenuator is designed with a specific attenuation value that is sufficient to prevent oscillation and stabilize the circuit, but not so large as to cause significant signal loss. This balanced approach achieves the minimum necessary attenuation to resolve the stability issue while preserving signal integrity.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS11290076B2Amplifier circuit, front-end circuit, and receiver circuit

Publication Date: 2022.03.29 MURATA MFG CO LTD

AI summary

An amplifier circuit includes a first terminal and a second terminal, an amplifier disposed in a first path connecting the first terminal and the second terminal, a first switch circuit disposed in the first path between the amplifier and the second terminal, an attenuator disposed in the first path between the amplifier and the first switch circuit, and a second switch circuit disposed in a second path that is connected to the first terminal and the second terminal while bypassing the amplifier, the attenuator, and the first switch circuit.