Amplifier Output Stage Diode Clamp for Overshoot Suppression
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Solution Overview
Problem
Conventional amplifier circuits experience overshoot issues due to insufficient phase margin, leading to unstable signal output and potential circuit damage, requiring costly design adjustments and increased fabricating costs to stabilize output voltage.
Innovation Solution
Incorporating a diode device between the output and input ends of the amplifier circuit, which turns on during voltage differences exceeding a barrier voltage to rapidly stabilize output voltage in transient states and cuts off in steady states to maintain normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a larger phase margin is designed to suppress overshoot, then the output voltage stability is improved, but the dynamic response becomes slower
Solution Approach 1:
The diode device is pre-configured between the output end and input end of the amplifier circuit, ready to activate when overshoot occurs. This preliminary arrangement allows the circuit to quickly respond to transient voltage spikes without requiring redesign of the amplifier's phase margin characteristics, thus maintaining both stability and fast response.
Solution Approach 2:
The diode device acts as an intermediary element that selectively activates during transient overshoot conditions. When the voltage difference exceeds the diode's barrier voltage, it provides a discharge path for the excessive voltage, thereby suppressing overshoot without affecting the normal dynamic response of the amplifier circuit.
2Speed
If current is increased to speed up the transient state change, then the dynamic response is improved, but the fabricating cost increases
Solution Approach 1:
The diode device is a simple, inexpensive component that is activated only temporarily during overshoot events. Unlike increasing current which requires more powerful (and expensive) amplifier components, the diode provides a low-cost solution that activates only when needed, maintaining normal operating costs while addressing transient issues.
3Reliability
If capacitors are added to the output end to reduce oscillation amplitude, then the output voltage stability is improved, but the circuit area increases
Solution Approach 1:
Instead of adding components to the output end, the diode device extracts the excess energy by providing a discharge path from the output end back to the input end during overshoot conditions. This approach stabilizes the output voltage without requiring additional capacitors that would increase circuit area.
Solution Approach 2:
The diode device utilizes the existing circuit structure by nesting its function within the feedback path of the amplifier. The diode is connected between the output and input ends, effectively using the existing signal path to suppress overshoot without requiring separate stabilization circuitry that would occupy additional space.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The diode device effectively suppresses overshoot in amplifier circuits by quickly addressing voltage fluctuations during transient states without affecting steady-state operation, thus preventing circuit instability and reducing fabricating costs.
Implementation Method 1
When a voltage difference between the output end and the at least one of the first and second input ends of the output amplifier is greater than a barrier voltage of the diode device, the diode device is turned on
Data Source
AI summary
An amplifier circuit including an input amplifier, an output amplifier and a diode device is provided. The output amplifier includes a PMOSFET and an NMOSFET. The PMOSFET has a gate electrode serving as a first input end and a drain coupled to an output end. The NMOSFET has a gate electrode serving as a second input end and a drain coupled to the output end. The output amplifier outputs an output voltage at the output end, and is coupled to the input amplifier via at least one of the first and second input ends. The diode device is coupled between the output end and the at least one of the first and second input ends of the output amplifier. When a voltage difference between the output end and the at least one of the first and second input ends of the output amplifier is greater than a barrier voltage of the diode device, the diode device is turned on, and an overshoot of the output voltage is reduced.