Amplifier Output Clamp with Current Limiting Against Contention
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Solution Overview
Problem
Existing amplifier circuits face contention issues when coupled with clamp circuits, leading to undesired current flow and potential damage, especially when the input signal is non-compliant and the feedback circuit is present, which disrupts the desired clamping effect.
Innovation Solution
Incorporating a clamp sense circuit and a current limiter in series with the amplifier's stages to sense and control current flow based on the voltage at the sensing node, allowing the clamp circuit to limit current through specific conduction paths and prevent contention with the amplifier's internal stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a clamp circuit is coupled to the output of an amplifier to limit the output signal level, then the output signal can be clamped to a predetermined level, but high currents flow through the clamp circuit and amplifier stages causing contention and potential damage
Solution Approach 1:
A current limiter circuit is introduced as an intermediary component between the amplifier stages and the clamp circuit. This current limiter acts as a mediator that controls and restricts the current flowing through the clamp circuit to predetermined safe levels, preventing the harmful high current effects while allowing the clamp circuit to function properly in limiting the output signal voltage.
Solution Approach 2:
The current limiter is configured to limit the current through the clamp circuit before the clamp circuit attempts to clamp the output signal. By establishing current limits in advance through the current limiter, the system prevents contention and potential damage before they occur, ensuring safe operation of the clamp circuit.
2Ease of operation
If the amplifier stages continue to force the output signal to a level established by non-compliant input signal, then the amplifier maintains its gain transfer function, but the clamp circuit cannot achieve the desired clamping effect due to contention
Solution Approach 1:
The current limiter serves as an intermediary control mechanism that reconciles the conflict between the amplifier's tendency to maintain its gain transfer function and the clamp circuit's need to limit the output signal. By controlling the current available to the clamp circuit, the current limiter enables the clamp to activate and function without creating harmful contention with the amplifier stages.
Data Source
AI summary
Methods and devices for clamping an output of an amplifier stage of an amplifier are presented. According to one aspect, a clamp sense circuit senses a voltage at a node of an internal stage of the amplifier. The clamp sense circuit senses a region of operation of the clamp circuit and correspondingly controls a current limiter that is introduced in the amplifier to limit a current through the internal stage of the amplifier. Limiting the current in turn causes limiting a current path from a clamp circuit through the output of the amplifier stage. According to another aspect, the clamp sense circuit is a replica of the amplifier stage of the amplifier, the output of the amplifier stage coupled to the clamp circuit, and an output of the replica decoupled from the clamp circuit.