Oscillator Interface Circuit With RC-CR Quadrature Phase Correction

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Solution Overview

Problem

Conventional quadrature clock generation circuits face limitations such as requiring input clock signals at least twice the frequency of generated quadrature clock signals, high power consumption, narrow operating frequency range, large area, and degradation in external clock signal quality.

Innovation Solution

The proposed solution involves an oscillator interface circuit with a parallel combination of a resistor-capacitor (RC) low pass filter and a capacitor-resistor (CR) high pass filter, connected between pins receiving differential input clock signals from an external oscillator. This RC-CR filter stage allows for tunable quadrature clock generation with programmable resistor and capacitor values, enabling flexible operation across a wide frequency range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional quadrature clock generation circuits are used, then quadrature clock signals can be generated, but the input clock signal frequency must be at least twice the frequency of the generated quadrature clock signals

Engineering Contradiction:

Improveinput frequency rangeVSAvoidfrequency ratio constraint

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent changes the fundamental operating parameters of the clock generation circuit by using a parallel RC-CR filter configuration instead of conventional approaches. This allows the circuit to generate quadrature clock signals at the same frequency as the input clock signal, eliminating the traditional frequency ratio constraint and expanding the adaptable input frequency range.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If conventional quadrature clock generation circuits are used, then quadrature clock signals can be generated, but power consumption is high

Engineering Contradiction:

Improveclock generation efficiencyVSAvoidpower consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent replaces active clock generation mechanisms with a passive RC-CR filter-based approach. By using resistive and capacitive elements in a parallel configuration, the circuit generates quadrature signals without requiring high-power active components, thereby significantly reducing power consumption while maintaining clock generation functionality.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If conventional quadrature clock generation circuits are used, then quadrature clock signals can be generated, but the operating frequency range is narrow

Engineering Contradiction:

Improveoperating frequency rangeVSAvoidfrequency operation stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The parallel RC-CR filter configuration provides multi-functionality by simultaneously achieving wide frequency range operation and maintaining signal integrity. The circuit can operate across a broad frequency spectrum while generating accurate quadrature signals, making it universally applicable across different frequency requirements without sacrificing reliability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Productivity

If conventional quadrature clock generation circuits are used, then quadrature clock signals can be generated, but the circuit area is large

Engineering Contradiction:

Improveintegration densityVSAvoidcircuit area

Core Design Contradiction:

ProductivityVSArea of stationary object

Solution Approach 1:

The patent merges the quadrature signal generation function into a compact parallel RC-CR filter structure. By combining resistive and capacitive elements in a parallel configuration, the circuit achieves quadrature signal generation in a smaller area compared to conventional separate filter and generation stages, thereby improving integration density.

Inventive Principle:

Principle #5Merging (Combining)

5Reliability

If conventional quadrature clock generation circuits are used, then quadrature clock signals can be generated, but external clock signal quality degrades

Engineering Contradiction:

Improveclock signal qualityVSAvoidsignal degradation

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The parallel RC-CR filter acts as an intermediary between the input clock signal and the generated quadrature signals. This intermediate filtering stage preserves the quality of the external clock signal by providing a controlled impedance path and minimizing signal degradation, thereby maintaining high signal integrity throughout the conversion process.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS12328099B2Apparatus and methods for local oscillator interface circuits with quadrature clock generation and phase correction

Publication Date: 2025.06.10 ANALOG DEVICES INC

AI summary

Apparatus and methods for oscillator interface circuits with quadrature clock generation and phase correction are disclosed. In certain embodiments, a clock system includes an external oscillator that provides a differential input clock signal, and a semiconductor die that includes a first pin that receives a non-inverted component of the differential input clock signal and a second pin that receives an inverted component of the differential input clock signal. The semiconductor die further includes an oscillator interface circuit that includes a first controllable resistor and a first controllable capacitor connected in series between the first pin and the second pin, and a second controllable resistor and a second controllable capacitor connected in series between the second pin and the first pin.