Ring Oscillator Time Measurement with Randomized Phase Locking
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Solution Overview
Problem
Time measuring circuitry with ring oscillators faces nonlinearity issues due to device variation, leading to poor linearity and measurement accuracy, despite PLL control efforts.
Innovation Solution
Incorporating a phase randomizer that generates random numbers to offset the phase of the oscillation signal, dispersing nonlinearity and improving linearity by generating a new random number for each time measurement, which is used to adjust the oscillation control signal and synchronize the phase with the reference signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If delay times of delay circuitries in a ring oscillator are adjusted to generate an oscillation signal, then time measurement can be performed, but device variation causes non-constant delay time resulting in poor linearity
Solution Approach 1:
The patent implements feedback control by using the output signal from the time-to-digital converter to adjust the oscillation control signal through an adder. The phase randomizer introduces random phase shifts based on generated random numbers, and this feedback mechanism continuously compensates for nonlinearity caused by device variation, thereby improving time measurement linearity
Solution Approach 2:
The patent changes the oscillation control signal parameter dynamically by adding random phase shift values to compensate for nonlinearity. The phase randomizer generates random numbers that are converted to phase shift amounts, and these parameter changes are applied to the oscillation control signal to counteract device variation effects and improve measurement linearity
2Measurement precision
If PLL control is performed to improve linearity of time measuring circuitry, then measurement accuracy improves, but circuitry becomes complicated
Solution Approach 1:
The patent introduces a phase randomizer as an intermediary component that generates random phase shifts to compensate for nonlinearity. This intermediary element simplifies the overall control mechanism compared to traditional PLL circuits by directly injecting random phase corrections rather than requiring complex phase-locked loop components and control mechanisms
3Measurement precision
If a phase randomizer generates random numbers to offset phase of oscillation signal, then nonlinearity is dispersed and linearity improves, but additional circuitry is added
Solution Approach 1:
The patent converts the harmful effect of device variation and nonlinearity into a benefit by using random phase shifts. The phase randomizer intentionally introduces randomness that disperses nonlinearity effects, transforming what would be measurement errors into a statistical averaging effect that improves overall linearity when multiple measurements are taken
Data Source
AI summary
Time measuring circuitry has a ring oscillator, a time-to-digital converter, a time measurer and a phase randomizer. The ring oscillator has a plurality of delay circuitries connected in a ring shape, the ring oscillator adjusting delay times of the plurality of delay circuitries based on an oscillation control signal to generate an oscillation signal. The time-to-digital converter quantizes a phase of the oscillation signal at a transition timing of a reference signal. The phase synchronizing circuitry to generate the oscillation control signal based on an output signal of the time-to-digital converter so that a phase of the oscillation signal coincides with a phase of the reference signal. The time measurer to measure a time interval based on the output signal of the time-to-digital converter. The phase randomizer to randomly shift the phase of the oscillation signal to be locked by the phase synchronizing circuitry.