Quadrature Oscillator Cross-Coupling Without Active Gm-Cells

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Solution Overview

Problem

Existing quadrature oscillator circuitry suffers from increased power consumption and phase noise due to the addition of active Gm-cells for cross-coupling, which deteriorates oscillator performance.

Innovation Solution

The implementation of a quadrature oscillator circuitry with cross-coupling circuits that utilize current-control devices and common-mode voltage signals to control the current flowing along the tail current paths, ensuring the common-mode voltage signals are in antiphase, thereby forming a set of quadrature oscillator signals without the need for additional active components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If active Gm-cells are added for cross-coupling to generate quadrature oscillator signals, then quadrature signal generation is achieved, but power consumption increases

Engineering Contradiction:

Improvequadrature signal generation capabilityVSAvoidpower consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent merges the cross-coupling function with the existing differential oscillator circuits by utilizing the tail current paths and common-mode voltage nodes of the oscillators themselves. The cross-coupling is achieved through shared current paths and voltage-controlled current sources rather than separate active Gm-cells, thereby eliminating additional power-consuming components while maintaining quadrature signal generation capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The tail current paths and common-mode voltage nodes of the differential oscillators are made multi-functional by using them for both oscillator operation and cross-coupling. The same current paths that sustain oscillation are also used to generate the quadrature relationship through voltage-controlled modulation, eliminating the need for dedicated cross-coupling components and reducing overall power consumption.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If active Gm-cells are added for cross-coupling to generate quadrature oscillator signals, then quadrature signal generation is achieved, but phase noise increases

Engineering Contradiction:

Improvequadrature signal generation capabilityVSAvoidphase noise

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The cross-coupling function is merged into the existing oscillator structure using the same current paths and voltage nodes, avoiding the introduction of separate active Gm-cells that would add phase noise. The quadrature relationship is established through passive coupling mechanisms and voltage-controlled current modulation that do not introduce additional noise sources.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent converts the inherent common-mode voltage variations in differential oscillators, which are normally unwanted artifacts, into useful control signals for cross-coupling. By utilizing these existing voltage variations to modulate the tail currents, the circuit achieves quadrature generation without introducing additional noise, effectively turning a potential source of interference into a beneficial control mechanism.

Inventive Principle:

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

3Adaptability or versatility

If additional active components are added for cross-coupling, then quadrature oscillator functionality is achieved, but device complexity increases

Engineering Contradiction:

Improvequadrature oscillator functionalityVSAvoidnumber of active components

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines multiple functions into existing components: the tail current paths serve both as bias current sources for oscillation and as cross-coupling pathways. The common-mode voltage nodes are utilized as control points for both oscillator operation and quadrature signal generation. This merging eliminates the need for separate active Gm-cells and reduces overall device complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

Existing components are made multi-functional: the differential pair transistors generate both the oscillator output and the cross-coupling control signals through their common-mode voltage variations. The LC tank circuits serve both frequency determination and signal coupling functions. This universal usage of components reduces the total number of active elements required while achieving full quadrature oscillator functionality.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentEP3829056B1Quadrature oscillator circuitry and circuitry comprising the same

Publication Date: 2024.01.03 SOCIONEXT INC

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AI summary

Quadrature oscillator circuitry (800), comprising: a first differential oscillator circuit having differential output nodes (12, 22) and configured to generate a first pair of differential oscillator signals (I+, I-) at those output nodes, respectively; a second differential oscillator circuit having differential output nodes (12, 22) and configured to generate a second pair of differential oscillator signals (Q+, Q-) at those output nodes, respectively; and a cross-coupling circuit (802, 804) connected to cross-couple the first and second differential oscillator circuits. The cross-coupling circuit may comprise a pair of cross-coupled transistors.