Feed-forward Control System with Current Estimator for Parasitic Impedance
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Solution Overview
Problem
High-frequency digital integrated circuits face challenges in designing circuit performance due to parasitic impedances from capacitors, which cause unwanted voltage drops and noise, and existing solutions are complex and power-consuming.
Innovation Solution
A feed-forward control system with a current estimator is implemented, which estimates the output capacitor current using available voltage feedback signals, reducing circuit complexity and directly addressing parasitic impedances by generating a feedback signal to the voltage regulator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If existing feedback systems are used to compensate for parasitic impedances, then voltage drops and noise are reduced, but circuit complexity and power consumption increase
Solution Approach 1:
The patent creates a simplified model (copy) of the output capacitor's parasitic impedance characteristics using an RC network that replicates the ESR and ESL behavior. This model allows the control system to predict and compensate for parasitic effects without requiring direct measurement or complex sensing circuits, thereby reducing overall circuit complexity while maintaining compensation effectiveness.
Solution Approach 2:
The patent introduces an intermediary RC network that acts as a mediator between the voltage feedback signal and the control system. This intermediary network transforms the voltage feedback into a signal that directly represents the parasitic impedance effects, enabling simpler compensation logic in the control system without requiring direct interaction with the complex parasitic elements.
2Measurement precision
If direct capacitor current measurement is implemented, then parasitic impedance compensation is accurate, but additional sensing components and circuit complexity are required
Solution Approach 1:
Instead of directly measuring capacitor current with complex sensing components, the patent creates an electrical copy of the current information by processing the available voltage feedback signal through an RC network. This copied signal accurately represents the capacitor current and parasitic impedance effects without requiring direct current sensors or additional measurement hardware.
Solution Approach 2:
The system uses its existing voltage feedback signal to generate the information needed for parasitic compensation, rather than requiring external current sensors. The RC network processes the readily available voltage signal to self-generate the compensation information, eliminating the need for separate sensing components.
3Speed
If complex feedback systems are used to achieve fast response, then high-frequency operation is supported, but integrated circuit real estate and power consumption increase
Solution Approach 1:
The patent merges the parasitic compensation function with the existing voltage feedback path by integrating an RC network into the feedback loop. This combination allows the same feedback signal to serve dual purposes: providing voltage information and generating parasitic compensation signals, thereby achieving fast response without requiring separate complex feedback circuits that would consume additional area and power.
Data Source
AI summary
A method and apparatus for estimating capacitor current in a feed-forward control system includes a circuit that conducts a current through an output capacitor to ground and estimates a current magnitude for the current in an output current estimator. The current estimator generates a voltage that corresponds to the estimated current magnitude by creating a voltage drop across an estimator circuit capacitor that equals a voltage drop across the output capacitor, by creating a voltage drop across an output of an RC network of the estimator circuit that equals or is proportional to a voltage drop across the output capacitor due to parasitic inductance and parasitic resistance of the output capacitor. The voltage drop across the output of the RC network of the estimator circuit is proportional to current flowing through the parasitic inductance and resistance of the output capacitor.