Amplifier Output Clamp With Current Limiter for Contention Control
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Solution Overview
Problem
Existing amplifier circuits face contention issues when coupled with clamp circuits, leading to undesired current flows 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 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 with feedback circuit, then the output signal can be clamped to a predetermined level, but contention occurs between the amplifier stages and clamp circuit causing high current flow 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 flow to a safe level, preventing the harmful contention current from damaging the amplifier stages while still allowing the clamp circuit to perform its voltage clamping function accurately.
Solution Approach 2:
The current limiter is configured to preemptively limit the current flow before it can reach harmful levels. By placing the current limiter in the signal path ahead of the clamp circuit, the system proactively prevents excessive current from developing, thereby avoiding contention damage before it occurs while maintaining reliable output clamping.
2Adaptability or versatility
If the amplifier stages continue to force output signal to a level established by non-compliant input signal, then the amplifier transfer function is maintained, but the clamp circuit fails to reproduce desired clamping effect and generates high currents
Solution Approach 1:
The system employs feedback control where the output of the clamp circuit is fed back to control the current limiter. When the output voltage exceeds the predetermined clamping level, the feedback signal activates the current limiter to restrict current flow, thereby preventing contention while maintaining the amplifier's transfer function for compliant input signals.
Solution Approach 2:
The current limiter dynamically changes its electrical parameters (such as resistance) based on the operating conditions. Under normal operation, the current limiter has low impedance to maintain amplifier transfer function, but when clamping is required, it transitions to high impedance to limit current and prevent harmful contention effects.
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.