Multi-Level Mixing Clock Scheme for Time-of-Flight Camera Power Reduction

Solution Overview

Problem

Time-of-flight cameras face high power consumption due to large load capacitance and high modulation frequencies in their mixing drivers, which limits their efficiency and battery life in portable devices.

Innovation Solution

Implementing a multi-level mixing clock scheme in the circuitry of time-of-flight cameras to reduce power consumption by using step-function modulation signals with multiple voltage levels, which charge and discharge storage capacitors more efficiently, thereby reducing the total average power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If conventional single-level mixing clock scheme is used, then modulation depth is sufficient, but power consumption is high

Engineering Contradiction:

Improvepower consumptionVSAvoidmodulation depth

Core Design Contradiction:

Use of energy by moving objectVSPower

Solution Approach 1:

The patent segments the modulation signal into multiple voltage levels (e.g., 3-level: VDD, VDD/2, GND) instead of using a single binary level. This segmentation allows the mixing driver to charge and discharge capacitors in steps, reducing the total charge movement required and thereby lowering power consumption while maintaining sufficient modulation depth through the cumulative effect of multiple smaller voltage transitions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the voltage parameter of the mixing clock signal from a binary (2-level) scheme to a multi-level scheme. By introducing intermediate voltage levels between VDD and GND, the signal transitions require less charge transfer, directly reducing the power consumption described by P=CV²f, while the multi-level nature preserves the necessary modulation depth for accurate time-of-flight measurement.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If load capacitance is reduced, then power consumption decreases, but signal integrity deteriorates

Engineering Contradiction:

Improvepower consumptionVSAvoidsignal integrity

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent changes the voltage parameter of the mixing clock signal from a binary (2-level) scheme to a multi-level scheme. By introducing intermediate voltage levels between VDD and GND, the signal transitions require less charge transfer, directly reducing the power consumption described by P=CV²f, while the multi-level nature preserves the necessary modulation depth for accurate time-of-flight measurement.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11681026B2Electronic device, method and computer program

Publication Date: 2023.06.20 SONY SEMICON SOLUTIONS CORP

AI summary

An electronic device comprising circuitry configured to drive a unit pixel for a time of flight camera according to a multi-level mixing clock scheme.