Multiplexed Input Buffering for Faster Clamp Recovery
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Solution Overview
Problem
In signal acquisition systems, the activation of input clamp protection during multiplexer switching leads to significant current draw from filters, causing prolonged settling time and signal throughput limitations, and existing solutions either use smaller filters or increase circuit complexity by employing reference channels.
Innovation Solution
A buffer stage is introduced between the multiplexer output and the amplifier input, which can be switched into the signal path during clamping events to limit current draw from filters, allowing the buffer to provide necessary current and reducing filter recharge, thereby minimizing settling time without bypassing ESD protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If input clamp protection is activated during multiplexer switching, then amplifier input is protected from overload, but current draw from filters increases significantly causing prolonged settling time
Solution Approach 1:
A buffer stage is introduced as an intermediary element between the multiplexer output and the amplifier input. This buffer provides the necessary current during clamping events without drawing it from the input filters, thereby protecting the amplifier while avoiding the settling time penalty. The buffer acts as a current source that decouples the clamping current demand from the filter recharge process.
2Productivity
If smaller filters are used to reduce settling time, then signal throughput improves, but filter performance and signal quality deteriorate
Solution Approach 1:
The buffer stage serves as a mediator that allows larger filters to be used without compromising signal throughput. By providing current during transient events, the buffer eliminates the need for filters to recharge during clamping events, thus removing the constraint that would otherwise force the use of smaller filters. This enables optimization of filter performance independent of throughput requirements.
3Loss of time
If reference channels are used to minimize settling time, then switching transitions are controlled, but circuit complexity increases
Solution Approach 1:
The reference channel mechanism is extracted and replaced by a simpler buffer stage that directly addresses the root cause of settling time issues. Instead of using a separate reference channel to control switching transitions, the buffer provides current during any clamping event regardless of the switching pattern, eliminating the need for complex reference channel logic while achieving the same settling time improvement.
Data Source
AI summary
An acquisition device and corresponding method for operating the acquisition system are provided. Generally, during operation a plurality of input signals are filtered and multiplexed. The multiplexed input signals are then applied to an amplifier stage; however, when a clamping condition for the amplifier stage occurs, a buffer is switched into a signal path between a multiplexer and an amplifier stage so as to generally reduce the current draw on the input filters.