Transformer-Coupled VCO Output Matching for Low-Power Signal Drive

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Solution Overview

Problem

Voltage-controlled oscillators face challenges in achieving high-frequency impedance matching with low power consumption, as existing methods either increase power consumption or struggle with parasitic components on semiconductor substrates, making it difficult to deliver large signal power to mixer circuits with predetermined impedance.

Innovation Solution

A voltage-controlled oscillator design incorporating a differential alternating current generator with a resonator and pair of transformers, where the alternating current is conducted through primary and secondary inductors, and an impedance-matching circuit connected to the secondary inductors, allowing for efficient impedance matching and low power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If impedance matching is achieved using conventional methods (load circuit at collector, cascode amplifier, or driver circuit), then power transfer efficiency is improved, but device complexity and power consumption increase

Engineering Contradiction:

Improvepower consumptionVSAvoidcircuit complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent extracts the impedance matching function from the traditional collector/load circuit area and implements it separately at the emitter through an impedance matching circuit. This separation allows the collector to focus on signal generation while the emitter handles impedance transformation, reducing overall circuit complexity and power consumption.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces an impedance matching circuit as an intermediary component at the emitter that transforms the low emitter impedance to match the load impedance. This intermediary circuit enables efficient power transfer without requiring complex collector-side modifications or additional amplification stages.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of energy

If transformer turn ratio is adjusted for impedance matching, then power transfer efficiency is improved, but device complexity and adjustment difficulty increase

Engineering Contradiction:

Improvepower transfer efficiencyVSAvoidimpedance matching adjustability

Core Design Contradiction:

Loss of energyVSEase of operation

Solution Approach 1:

The patent changes the approach from adjusting transformer turn ratios to using an impedance matching circuit with fixed or easily adjustable components at the emitter. This parameter change simplifies the impedance matching process and makes it more adaptable to different load conditions without requiring complex transformer redesign.

Inventive Principle:

Principle #35Parameter changes

3Power

If large signal power is delivered to mixer circuit, then communication performance is improved, but power consumption of oscillator increases

Engineering Contradiction:

Improvesignal power outputVSAvoidoscillator power consumption

Core Design Contradiction:

PowerVSUse of energy by moving object

Solution Approach 1:

The patent converts the inherently low impedance at the emitter, which is typically a disadvantage for power output, into a benefit by using it as the basis for an efficient impedance matching circuit. This transformation allows the oscillator to deliver large signal power to the mixer circuit while maintaining low power consumption through efficient impedance transformation rather than power amplification.

Inventive Principle:

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

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration enables the outputting of large signal power with impedance matching to a predetermined level at low power consumption, effectively addressing the challenges of high-frequency impedance matching and reducing power consumption in voltage-controlled oscillators.

Implementation Method 1

a pair of transformers 31, 32 each having a primary inductor and a secondary inductor, for conducting the alternating current to each primary inductor

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a differential alternating current generator 20 including a resonator 10 capable of varying resonant frequency according to an input control voltage, for generating a pair of differential alternating current each of which having the same frequency with the resonant frequency of the resonator

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS7839229B2Voltage-controlled oscillator and communication device using the same

Publication Date: 2010.11.23 HITACHI LTD

AI summary

The present invention provides a voltage-controlled oscillator operating from microwave frequencies to millimeter wave frequencies, which is capable of outputting a large power with an output impedance thereof being set up to a predetermined level at low power consumption, and a communication device using the same. The voltage-controlled oscillator includes: a differential alternating current generator including a resonator capable of varying resonant frequency according to an input control voltage, for generating a pair of differential alternating current each of which having the same frequency with the resonant frequency of the resonator yet being 180 degrees out of phase in mutual; a pair of transformers each of which having a primary inductor and a secondary inductor, for conducting the alternating current to the primary inductor; and an impedance-matching circuit connected to the secondary inductor of the transformers, wherein an output signal is outputted from the secondary inductors of the transformers.