Reference Current Generating Circuit with Phase-Comparison Calibration

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Solution Overview

Problem

Conventional reference current generating circuits face challenges in maintaining a stable current value due to manufacturing variability and temperature effects, leading to increased power consumption and cost when using off-chip passive elements, and inefficiencies in analog circuitry.

Innovation Solution

A reference current generating circuit with a variable current supply, delay circuitry, phase comparator, and control circuitry that calibrates the current value based on phase comparison, allowing for high-accuracy reference current generation with reduced variability and temperature dependence.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If off-chip passive elements are used to generate reference current, then manufacturing precision is improved, but cost increases

Engineering Contradiction:

Improvecurrent value accuracyVSAvoidcost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent replaces passive electrical elements (resistors, capacitors) with an active digital control system consisting of a current control unit, delay unit, and phase comparison unit. This substitution allows the reference current to be generated through digital signal processing and feedback control rather than relying on precision passive components, thereby reducing manufacturing cost while maintaining current accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system implements self-calibration through phase comparison between the input clock and delayed clock signals. The current control unit automatically adjusts the reference current based on the phase difference detected by the comparison unit, enabling the system to compensate for its own variations without external intervention or calibration equipment.

Inventive Principle:

Principle #25Self-service

2Device complexity

If conventional reference current generating circuitry is used, then device complexity is reduced, but current stability deteriorates due to manufacturing variability

Engineering Contradiction:

Improvecircuit structureVSAvoidcurrent value stability

Core Design Contradiction:

Device complexityVSStability of the object's composition

Solution Approach 1:

The patent implements a feedback control loop where the phase comparison unit continuously monitors the phase difference between the input clock and delayed clock, and the current control unit adjusts the reference current based on this feedback. This closed-loop system compensates for variations in delay characteristics and maintains stable reference current generation despite manufacturing variability.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts the reference current value based on real-time phase comparison results. Rather than relying on fixed passive component values, the active control system continuously adapts the current to compensate for environmental variations and manufacturing tolerances, transforming a static problem into a dynamic solution.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS9874895B2Reference current generating circuitry, A/D converter, and wireless communication device

Publication Date: 2018.01.23 KK TOSHIBA

AI summary

A reference current generating circuit has a variable current supply to output a reference current, delay circuitry to generate a reference clock by delaying a clock by a reference delay amount and a delay clock by delaying the clock depending on a current value of the reference current, a phase comparator to compare a phase of the reference clock with a phase of the delay clock to output a comparison result, and control circuitry to control the current value of the reference current based on the compared result.