Amplifier Squelch Circuit With Current Bypass Gain Suppression
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Solution Overview
Problem
Existing amplifier designs face challenges in reducing gain significantly during squelch operations without causing power fluctuations or component stress, especially when parts are powered down, which can degrade or damage sensitive components.
Innovation Solution
A squelch circuit is integrated with an amplifier, utilizing a bypass switch and control circuit to bypass current from the amplifier, maintaining consistent power consumption and avoiding component stress by using a control circuit with a biased voltage divider and control switches to manage bypass transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If power is reduced to parts of the amplifier during squelch operations, then gain is reduced, but power fluctuations and component stress occur which can degrade or damage sensitive components
Solution Approach 1:
The patent introduces a current source as an intermediary element that provides a controlled path for amplifier current during squelch operations. This current source acts as a mediator between the amplifier and ground, allowing the amplifier to be turned off while maintaining a steady current flow that prevents voltage fluctuations and component stress. The current source effectively decouples the amplifier shutdown from direct power rail disruptions.
Solution Approach 2:
The patent changes the operational parameters of the amplifier by controlling the tail current through a current source rather than directly powering down the amplifier. By adjusting the current source activation state, the amplifier can transition between active and squelched states without abrupt power changes. This parameter change approach maintains electrical stability while achieving gain reduction.
2Power
If amplifier gain is reduced during squelch operations, then signal output is suppressed, but power consumption fluctuates which affects system stability
Solution Approach 1:
The patent ensures continuous useful action by maintaining a steady current through the current source even when the amplifier is in squelch mode. Rather than completely cutting off power, the current source continues to provide controlled current flow, ensuring continuous but reduced power consumption. This approach eliminates power consumption fluctuations while still achieving the desired gain suppression during squelch operations.
3Power
If bypass switches are used to reduce amplifier gain, then gain control is achieved, but circuit complexity increases
Solution Approach 1:
The patent implements multi-functionality by designing the current source to serve multiple purposes: it provides biasing current during normal operation, acts as a controlled shutdown path during squelch operations, and maintains electrical stability throughout. This single multi-functional element replaces what would otherwise require multiple separate components, thereby achieving gain control without proportionally increasing circuit complexity.
Data Source
AI summary
Amplifiers incorporating squelch circuits and functionality are described. An example amplifier circuit includes an amplifier and a squelch circuit coupled to the amplifier. The squelch circuit is configured to squelch an output of the amplifier by bypassing current from the amplifier. The squelch circuit can include a bypass switch coupled with a transistor of the amplifier and a control circuit coupled to the bypass switch. The control circuit can be configured to control operation of the bypass switch. The bypass switch can be implemented as a bypass transistor coupled in parallel with a transistor of the amplifier. The control circuit can include a biased voltage divider leg with a pair of resistors, a current source coupled at a node between the pair of resistors, and a pair of control switch transistors coupled across a resistor among the pair of resistors.