PLL Voltage-Controlled Oscillator With Process Offset Compensation

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Solution Overview

Problem

The existing phase-lock loop (PLL) circuits face challenges due to process offsets, leading to over-design of operating frequency ranges, which increases circuit area and power consumption.

Innovation Solution

A voltage-controlled oscillator (VCO) with a process compensation device is introduced, which generates a compensation current proportional to the transistor operation speed corresponding to the process offset. This compensation current is subtracted from the linear current to generate a control current, allowing the PLL circuit to operate within the desired frequency range without over-design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the operating frequency range is over-designed to accommodate process offsets, then the reliability is improved, but the circuit area increases

Engineering Contradiction:

ImprovereliabilityVSAvoidcircuit area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent changes the parameter of current by introducing a compensation current that is subtracted from the linear current to generate a control current. This parameter change allows the circuit to maintain reliable operation across process offsets without requiring an over-designed frequency range, thereby reducing circuit area while preserving reliability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent extracts the offset effect by generating a compensation current that specifically counteracts the process offset. By separating and compensating for the offset component, the circuit achieves reliable operation without needing to over-design the entire frequency range, thus reducing the required circuit area.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If the operating frequency range is over-designed to accommodate process offsets, then the reliability is improved, but the power consumption increases

Engineering Contradiction:

ImprovereliabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by stationary object

Solution Approach 1:

The patent changes the current parameter by introducing a compensation current mechanism. This allows the circuit to maintain reliable operation across process variations without requiring an expanded frequency range, thereby reducing power consumption while preserving reliability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the harmful effect of process offsets into a beneficial compensation mechanism. By generating a compensation current that counteracts the offset, the circuit achieves reliable operation without over-designing the frequency range, thus reducing power consumption while maintaining reliability.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Area of stationary object

If the operating frequency range is reduced without over-design, then the circuit area is reduced, but the reliability deteriorates due to process offsets

Engineering Contradiction:

Improvecircuit areaVSAvoidreliability

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

The patent introduces a compensation current as an intermediary element that mediates between the linear current and the final control current. This intermediary compensation mechanism allows the circuit to operate reliably within a reduced frequency range by actively compensating for process offsets, thus reducing circuit area without sacrificing reliability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the control current parameter by subtracting the compensation current from the linear current. This parameter modification enables the circuit to maintain reliable operation across process offsets within a reduced frequency range, achieving both smaller circuit area and preserved reliability.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12278641B2Phase-lock loop circuit, voltage-controlled oscillator and compensation method

Publication Date: 2025.04.15 NUVOTON

AI summary

The present disclosure provides a voltage-controlled oscillator for a phase-lock loop circuit. The voltage-controlled oscillator is used to receive a control voltage and generate a clock signal, and includes a voltage-to-current device, a process compensation device, a subtraction unit and a clock signal generating module. The voltage-to-current device is used to generate a linear current according to the control voltage. The process compensation device is used to generate a compensation current according to the control voltage. The compensation current is proportional to a transistor operation speed corresponding to a process offset. The subtraction unit is electrically connected to the voltage-to-current device and the process compensation device, and is used to subtract the compensation current from the linear current to generate the control current. The clock signal generating module is electrically connected to the subtraction unit, and is used to generate the clock signal according to the control current.