Voltage Regulator Noise Cancellation via Inverted Signal Coupling
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Solution Overview
Problem
Voltage regulators face challenges in achieving effective supply voltage rejection (SVR) due to parasitic capacitances, which worsen as frequency increases, leading to noise coupling and degradation in performance, especially in integrated circuits where layout modifications and shielding are insufficient.
Innovation Solution
A noise compensation circuit is introduced that capacitively couples an inverted version of the alternating component to a high-impedance node in the voltage regulator, canceling noise signals through a compensation capacitor and inverting buffer, thereby reducing parasitic capacitive coupling effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If layout modifications and shielding are used to reduce parasitic capacitances, then SVR performance is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent introduces a compensation capacitor as an intermediary element connected between the high-impedance node and a reference potential. This compensation capacitor mediates the harmful capacitive coupling by providing an alternative path for noise currents, thereby improving SVR performance without requiring complex layout modifications or shielding structures.
Solution Approach 2:
The patent changes the electrical parameters of the circuit by adding the compensation capacitor, which modifies the impedance characteristics and noise coupling paths. By adjusting the compensation capacitor value, the SVR performance can be optimized without changing the physical layout or adding shielding, thus avoiding increased device complexity.
2Area of stationary object
If integrated circuit components are placed close together, then area is reduced, but parasitic capacitances increase causing SVR degradation
Solution Approach 1:
The compensation capacitor serves as an intermediary that compensates for the harmful effects of small spacing between components. By connecting the high-impedance node to reference potential through this capacitor, the adverse effects of parasitic capacitances arising from close component placement are mitigated, allowing compact layout while maintaining SVR performance.
Solution Approach 2:
The patent converts the harmful parasitic capacitances that result from close component placement into a beneficial effect. The compensation capacitor, which could be seen as an additional parasitic element, is actually used to cancel out the harmful coupling effects, thereby improving SVR performance while maintaining compact area.
3Productivity
If frequency of operation is increased, then productivity is improved, but capacitive coupling increases causing SVR to worsen
Solution Approach 1:
The compensation capacitor acts as a frequency-dependent intermediary that becomes increasingly effective at higher frequencies. As operating frequency increases, the compensation capacitor provides a lower impedance path for noise currents, thereby maintaining SVR performance even at high frequencies where parasitic capacitive coupling would normally deteriorate performance.
Solution Approach 2:
The patent introduces a dynamic compensation mechanism where the compensation capacitor's effectiveness varies with frequency. At higher operating frequencies, the compensation capacitor dynamically provides better noise rejection, allowing the system to maintain good SVR performance across a wide frequency range despite increasing capacitive coupling effects.
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
This approach significantly enhances SVR performance by effectively canceling noise at high-impedance nodes, improving the regulator's ability to reject noise across a wide frequency range, as demonstrated by improved post-layout and real integrated circuit simulations.
Implementation Method 1
capacitively coupling an inverted version of the alternating component to the high-impedance node
Implementation Method 2
parasitic capacitances in the femtofarad range. While femtofarad parasitic capacitances have extremely small values in absolute terms, the reactance values and resulting capacitive coupling introduced by such parasitic capacitances can be significant
Data Source
AI summary
A voltage regulator is controlled to improve supply voltage rejection by cancelling an alternating component of a supply voltage signal that is capacitively coupled to a high-impedance node within the voltage regulator. This cancellation is done by capacitively coupling an inverted version of the alternating component to the high-impedance node to thereby substantially cancel the alternating component present on the high-impedance node. The high-impedance node may be a high-impedance voltage reference node of the voltage regulator.