Clock Phase Shift Measurement Using Mixer and Low-Pass Filtering

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Solution Overview

Problem

Current methods for measuring phase shift between digital signals of the same frequency require extensive integrated hardware or costly laboratory equipment, making them inefficient and costly for precise temporal control in electronic signal processing.

Innovation Solution

A method involving a mixer and a low pass filter, potentially with an XOR gate, to measure phase shift by converting it into a proportional direct voltage, which can be measured using a voltmeter, allowing for simple and cost-effective implementation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If delay chains, oscillators, or PLLs are used for time measurement, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improvephase shift measurement precisionVSAvoidcircuit complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts only the essential function needed for phase shift measurement - using a simple mixer and low-pass filter to obtain a DC voltage proportional to phase difference - rather than implementing complete delay chains, oscillators, or PLLs. This extraction of the core measurement principle eliminates unnecessary circuit complexity while maintaining measurement capability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses a simplified model approach where the complex phase shift measurement problem is copied into a simpler equivalent form: converting phase shift measurement into DC voltage measurement through mixing and low-pass filtering. This copying to a simpler domain resolves the contradiction between precision and complexity.

Inventive Principle:

Principle #26Copying

2Adaptability or versatility

If integrated hardware for phase shift measurement is added to the chip, then measurement capability is improved, but manufacturing cost increases

Engineering Contradiction:

Improvephase shift measurement capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The mixer and low-pass filter components used in the patent are standard, multi-functional building blocks in electronic design that can serve multiple purposes beyond phase shift measurement. Using these universal components reduces manufacturing cost compared to designing specialized dedicated measurement hardware, while still providing the required adaptability for phase shift measurement.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Measurement precision

If subsampling is used to map short time intervals to longer intervals, then measurement precision is improved, but measurement time increases

Engineering Contradiction:

Improvetime interval measurement precisionVSAvoidmeasurement time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces the mechanical/time-based subsampling approach with an electrical field-based solution. Instead of counting cycles or using temporal sampling, the phase shift is directly converted into a DC voltage level through mixing and low-pass filtering. This substitution of the measurement domain from temporal to electrical eliminates the time loss inherent in subsampling methods while maintaining precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 enables independent measurement of phase shift without being dependent on duty cycles, requiring minimal circuit complexity and no special component precision, suitable for integration into integrated circuits.

Implementation Method 1

a-1) feeding the first clock signal into a first input of a mixer; a-2) feeding the second clock signal into a second input of the mixer

Methodology Applied

Scientific EffectMixing: Homodyne Detection

Implementation Method 2

d) feeding the output signal of the mixer into a low pass filter

Methodology Applied

Scientific EffectFiltering: Filter (electronic)

Data Source

PatentUS12066487B2Method and circuit for simple measurement of the phase shift between two digital clock signals having the same frequency

Publication Date: 2024.08.20 ROBERT BOSCH GMBH

AI summary

A method for simple measurement of phase shift between a first clock signal and a second clock signal is described, each clock signal having a period T0. The method includes: feeding the first clock signal into a first input of a mixer; feeding the second clock signal into a second input of the mixer; feeding the output signal of the mixer into a low pass filter; and measuring the output signal of the low pass filter, with the aid of an output voltage that is normalized to operating voltage of the mixer. A circuit for implementing the method includes a mixer and a low pass filter. The mixer includes a first input for feeding in the first clock signal, and a second input for feeding in the second clock signal. The output of the mixer is connected to the input of the low pass filter.