Time-to-Digital Converter Using Dual Oscillator Phase Sampling

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Solution Overview

Problem

Existing time-to-digital converter technologies face challenges in achieving sufficient timekeeping accuracy due to temperature characteristics, process variations, and jitter characteristics, which affect the clock signal generated by oscillators, leading to difficulties in controlling the start of oscillation and performing normal timekeeping operations.

Innovation Solution

A time-to-digital converter configuration comprising a first and second oscillation circuit, sampling circuits, and a processing circuit that obtain frequency and phase information from clock signals to calculate a digital value representing the time difference between start and stop signals, using a counter, storage circuit, and arithmetic circuit for accurate digital arithmetic processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a crystal oscillator is used to generate clock signals with favorable characteristics, then the clock signal quality is improved, but the ability to control the start of oscillation deteriorates

Engineering Contradiction:

Improveclock signal qualityVSAvoidstart control capability

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The system divides the time measurement function into two independent oscillation circuits: a first oscillation circuit that starts at a first timing and a second oscillation circuit that starts at a second timing. Each circuit generates clock signals with stable characteristics while maintaining independent start control capability through separate control signals.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Sampling circuits are introduced as intermediary components to capture the clock signals from both oscillation circuits at specific timings. These sampling circuits enable the system to obtain frequency and phase information without directly interfering with the oscillation start control, thus preserving both clock signal quality and start control capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If traditional timekeeping circuits are used to measure time intervals, then the circuit structure is simple, but the timekeeping accuracy deteriorates due to temperature characteristics, process variations, and jitter

Engineering Contradiction:

Improvecircuit structureVSAvoidtimekeeping accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The system merges multiple measurement functions into a unified architecture: two oscillation circuits generate clock signals, sampling circuits capture these signals, and a single processing circuit performs frequency measurement, phase measurement, and time interval calculation, thereby achieving high accuracy without proportionally increasing overall system complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent replaces traditional mechanical/time-based counting methods with digital signal processing. The processing circuit uses digital arithmetic operations to calculate time intervals based on sampled frequency and phase information, which are less susceptible to temperature characteristics, process variations, and jitter compared to traditional timekeeping circuits.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If multiple oscillation circuits are introduced to improve measurement accuracy, then the timekeeping accuracy is improved, but the device complexity increases

Engineering Contradiction:

Improvetimekeeping accuracyVSAvoidcircuit structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The processing circuit is designed as a multi-functional unit that performs frequency measurement, phase measurement, and time interval calculation for both oscillation circuits. This universal processing approach allows the system to achieve high measurement accuracy through multiple oscillation circuits while avoiding proportional increases in overall system complexity by sharing common processing resources.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS10303125B2Time-to-digital converter, circuit device, physical quantity measuring device, electronic apparatus, and vehicle

Publication Date: 2019.05.28 SEIKO EPSON CORP

AI summary

A time-to-digital converter includes first and second oscillation circuits, first and second sampling circuits, and a processing circuit. The first and second oscillation circuits start an oscillation operation in accordance with first and second signals and output first and second clock signals, respectively. The first and second sampling circuits perform sampling of the first and second clock signals by a first reference clock signal and output first and second output signals, respectively. The processing circuit obtains first frequency information and first phase information of the first clock signal and second frequency information and second phase information of the second clock signal based on the first and second output signals of the first and second sampling circuits, and obtains a digital value corresponding to a time difference of a transition timing between the first and second signals.