Voltage Regulator Signal Buffer Overshoot Control
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Solution Overview
Problem
Voltage regulators face significant output voltage overshoots when loads, such as memory units, switch between access and idle modes due to varying current demands, leading to instability and performance issues.
Innovation Solution
A voltage regulator design incorporating an operational amplifier, output transistor, and signal buffer that clamps the gate voltage to the output voltage during idle mode, maintaining the regulator in a closed-loop mode to reduce overshoot duration and amplitude, and uses a signal buffer with high input impedance and low output impedance to manage current variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional voltage regulator design is used, then the regulator can provide stable DC voltage under normal conditions, but significant output voltage overshoots occur when loads switch between access and idle modes
Solution Approach 1:
A signal buffer is introduced as an intermediary component between the operational amplifier and the output transistor. The buffer's high input impedance isolates the op-amp from rapid current changes, while its low output impedance provides stable voltage control to the transistor gate, effectively mediating the control signal during load transitions
Solution Approach 2:
The signal buffer proactively maintains the output transistor in a controlled state during idle mode by clamping the gate voltage, preparing the system for rapid response when the load transitions to access mode, thereby preventing voltage overshoot before it occurs
2Productivity
If the load current varies rapidly between access and idle modes, then the regulator responds to current demands, but the output voltage experiences prolonged overshoot with large amplitude
Solution Approach 1:
The signal buffer acts as a mediator that decouples the rapid load current variations from the voltage control path. Its high input impedance prevents direct coupling of current spikes to the op-amp output, while its low output impedance ensures stable voltage delivery to the load, reducing overshoot duration to less than 0.01 μs
Solution Approach 2:
The signal buffer changes the impedance parameters in the control path - presenting high input impedance to the op-amp and low output impedance to the load - thereby altering the system's dynamic response characteristics and minimizing voltage overshoot during rapid load transitions
3Productivity
If the load current varies rapidly between access and idle modes, then the regulator attempts to maintain voltage, but the overshoot amplitude exceeds acceptable levels
Solution Approach 1:
The signal buffer mediates between the control circuit and load by providing high input impedance to prevent current spikes from affecting the op-amp, and low output impedance to maintain precise voltage control, achieving overshoot amplitude reduction to less than 20 mV
Solution Approach 2:
By changing the impedance parameters at critical points in the circuit - high input impedance at the op-amp output and low output impedance at the buffer output - the system achieves both rapid load response and high voltage regulation precision during transient conditions
Data Source
AI summary
Voltage regulators and related methods are described. The voltage regulators described in the application may include an operational amplifier, an output transistor, and a signal buffer connected between the operational amplifier and the output transistor. In some embodiments, these voltage regulators are used in connection with memory units. A voltage regulator may be arranged such that the signal amplifier clamps the voltage at the gate of the output transistor to the output voltage when the memory unit is in an idle mode. In this way, when the memory is accessed, the amplitude and duration of output voltage overshoots can be limited, relative to some voltage regulators.