Ring Oscillator Kvcc Compensation for Low-Voltage Jitter Control
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Solution Overview
Problem
Ring oscillators exhibit high supply noise sensitivity (high Kvcc) and intrinsic jitter, making it challenging to generate high frequencies, especially at lower supply voltages, and existing solutions like cascaded regulators and K compensation require meticulous calibration and higher supply voltages.
Innovation Solution
A combination of a lower profile voltage regulator and partial K compensation block is used to attenuate Vcc noise, reducing supply sensitivity and easing regulator and compensator parameters, allowing operation at lower supply voltages with reduced PSRR requirements, while maintaining high-frequency operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a voltage regulator with very high PSRR is used to suppress supply noise, then supply noise sensitivity is reduced, but thermal and flicker noise of the regulator strongly impact oscillator jitter
Solution Approach 1:
The patent replaces the traditional voltage regulator approach with a noise compensation circuit that uses digital signal processing to subtract noise components from the oscillator output. This substitution avoids the thermal and flicker noise inherent in analog regulators while still achieving supply noise rejection through digital filtering and compensation techniques.
Solution Approach 2:
The patent introduces an intermediary noise compensation circuit that measures the oscillator output and actively compensates for supply noise effects. This intermediary system includes noise measurement circuitry and compensation circuitry that works between the oscillator and the output, separating the noise suppression function from the voltage regulation function.
2Object-affected harmful factors
If existing solutions like cascaded regulators and K compensation are used, then supply noise sensitivity is reduced, but meticulous calibration is required and higher supply voltages are needed
Solution Approach 1:
The patent implements a self-calibrating system where the noise compensation circuit automatically measures the oscillator's noise characteristics and adjusts its compensation parameters without external intervention. The system includes calibration logic that performs automatic tuning during startup or operation, eliminating the need for meticulous manual calibration while maintaining effective noise suppression.
3Object-affected harmful factors
If existing solutions like cascaded regulators and K compensation are used, then supply noise sensitivity is reduced, but higher supply voltages are required
Solution Approach 1:
The patent replaces the voltage regulator approach that requires high supply voltages with a digital noise compensation approach that operates efficiently at lower voltages. The digital signal processing and noise compensation circuits are designed to function at low supply voltages, eliminating the need for high-voltage regulators while maintaining noise suppression performance.
Data Source
AI summary
A circuit may comprise a first node, a ring oscillator, a regulator, and a Kvcc compensation circuit. The first node may be a supply node to provide a supply voltage for the circuit. The ring oscillator may be formed from inverters. The regulator may use a single transistor between the first node and a second node for powering the oscillator. The K compensation circuit may be used to provide to the oscillator a variable capacitive load that is dependent on the supply at the first supply node, and it may drag oscillator frequency down when the first node supply goes up.