Power Supply Droop Compensation Circuit for Slew Rate Enhancement
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Solution Overview
Problem
Switching power supplies with Adaptive Voltage Positioning (AVP) control face a slowdown in output voltage slew rate due to droop signals caused by output capacitance charge or discharge currents, which complicates circuit design and is not effectively addressed by existing methods.
Innovation Solution
A power supply circuit incorporating a Pulse Width Modulator (PWM) and a droop compensation circuit with a feed-forward network that sources or sinks a compensation current to remove the droop signal component, improving the slew rate of output voltage changes by compensating for the charge and discharge currents of the output capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If AVP control scheme is used to enhance thermal performance, then thermal performance is improved, but output voltage slew rate is slowed due to droop signal effects
Solution Approach 1:
The harmful droop signal component that slows the output voltage slew rate is extracted and removed from the feedback loop. The feed-forward network selectively removes the droop signal portion that is caused by output capacitance charge/discharge currents, while maintaining the beneficial AVP control function for thermal management.
Solution Approach 2:
A feed-forward network is introduced as an intermediary element between the error amplifier and the droop compensation circuit. This intermediary network processes the feedback signal to eliminate the droop effect before it impacts the output voltage slew rate, while preserving the AVP control functionality.
2Speed
If error signal compensation is added to increase slew rate, then output voltage slew rate is improved, but circuit complexity and area increase
Solution Approach 1:
The droop compensation function and the slew rate enhancement function are merged into a single feed-forward network structure. This unified approach eliminates the need for separate compensation circuits and error signal processing stages, thereby reducing overall circuit complexity and area while achieving both objectives simultaneously.
Solution Approach 2:
The feed-forward network performs multiple functions: it provides droop compensation, enhances the output voltage slew rate, and maintains AVP control functionality. This multi-functional design eliminates the need for additional dedicated circuits for each function, reducing overall system complexity.
Data Source
AI summary
A power supply and a method for compensating for a droop component in an output signal of the power supply. The power supply may include an error amplifier and an oscillator coupled to a pulse width modulation circuit. Outputs of the pulse width modulation circuit are connected to switching circuits that have outputs coupled to an output node. The power supply further includes a droop compensation circuit connected to the output of the power supply, the outputs of the switching circuits, and to an input of the error amplifier. The droop compensation circuit includes an amplifier coupled to a feed-forward network and a current source coupled to the feed-forward network. The current source sources a current to or sinks a current from the feed-forward network to generate a droop compensation signal that is transmitted to the error amplifier. The current source may be controlled by a digital-to-analog circuit.