PLL Voltage Regulator Frequency Locking
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Solution Overview
Problem
Adaptive on-time switching voltage regulators face significant variations in switching frequencies due to process variations such as on-resistance of field-effect transistors, comparator mismatch, and speed, leading to unstable frequency control.
Innovation Solution
The implementation of a phase-lock loop (PLL) with a pulse-width modulated (PWM) signal generator and phase detector to lock the switching frequency to a clock reference signal, along with a lock range extension circuit to maintain stability and extend the lock range, ensuring consistent switching frequency operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If adaptive on-time switching voltage regulators are used, then the regulator can operate with simple control, but the switching frequency varies significantly due to process variations
Solution Approach 1:
The patent implements a phase-lock loop (PLL) that continuously monitors the switching frequency and adjusts the on-time control signal to maintain a stable reference frequency. The PLL compares the actual switching frequency with a reference frequency and generates corrective feedback to compensate for process variations, thereby resolving the contradiction between simple control and frequency stability.
Solution Approach 2:
The patent dynamically adjusts the on-time parameter of the switching regulator based on feedback from the PLL. By changing the on-time duration in response to frequency deviations, the system maintains stable switching frequency despite process variations in transistor characteristics, resolving the contradiction between operational simplicity and frequency reliability.
2Ease of manufacture
If process variations are present, then manufacturing is easier, but the switching frequency varies by +1-25%
Solution Approach 1:
The PLL provides continuous feedback control that measures actual switching frequency and adjusts control parameters to maintain the reference frequency. This feedback mechanism compensates for manufacturing variations in transistor on-resistance and comparator characteristics, achieving frequency consistency despite ease of manufacture with standard process variations.
Solution Approach 2:
The system performs self-adjustment through the PLL, which automatically detects frequency deviations caused by process variations and corrects them without external intervention. The regulator self-compensates for manufacturing tolerances in real-time, maintaining precise frequency control while allowing easy manufacturing with standard process variations.
3Reliability
If a phase-lock loop is implemented to lock the PWM signal to a clock reference signal, then switching frequency stability is improved, but device complexity increases
Solution Approach 1:
The PLL circuit performs multiple functions: frequency stabilization, phase synchronization, and automatic frequency adjustment. By consolidating these functions into a single multi-functional block, the patent achieves frequency stability while minimizing the increase in overall device complexity compared to implementing separate control circuits for each function.
Data Source
AI summary
Adaptive on-time switching voltage regulator circuits and methods therefor provided. In some embodiments, a voltage regulator comprises: a switching circuit configured to generate a switching signal at a switching node according to a pulse-width modulated (PWM) signal; a phase-lock loop (PLL) configured to lock the PWM signal to a clock reference signal, the PLL comprising: a PWM signal generator configured to generate the PWM signal according to an error signal, and a phase detector configured to generate the error signal based on the PWM signal and the clock reference signal.