Complementary Push-Push Frequency Doubler for Differential Output Gain

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Solution Overview

Problem

Conventional frequency doublers suffer from low conversion gain and difficulty in producing differential outputs, which are essential for high-performance millimeter-wave transceiver systems, especially when operating at high frequencies.

Innovation Solution

A push-push frequency doubler based on complementary transistors, featuring a first and second differential amplifier circuit and an output load circuit, amplifies the second harmonic of differential input signals to produce a differential output signal with twice the initial frequency, utilizing NMOS and PMOS transistors to enhance conversion gain and output amplitude.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If conventional frequency doubler structure is used, then the circuit is simple, but the conversion gain is low

Engineering Contradiction:

Improveconversion gainVSAvoidcircuit structure

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The frequency doubler is divided into two separate differential amplifier circuits (first and second differential amplifier circuits), each processing one phase of the differential input signal. This segmentation allows independent optimization of each path to maximize conversion gain while maintaining overall circuit functionality.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent combines NMOS and PMOS differential amplifier circuits in a push-push configuration, merging their output signals to achieve constructive interference at the second harmonic frequency. This merging of complementary transistor types enhances the overall conversion gain beyond what a single amplifier type could achieve.

Inventive Principle:

Principle #5Merging (Combining)

2Ease of operation

If conventional frequency doubler structure is used, then the circuit is simple, but the differential output capability is poor

Engineering Contradiction:

Improvedifferential output capabilityVSAvoidcircuit structure

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent employs asymmetric configuration where the first differential amplifier circuit uses NMOS transistors and the second uses PMOS transistors. This asymmetry in transistor type selection creates complementary push-pull action that naturally generates balanced differential outputs with 180° phase difference, improving differential output capability.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The invention transitions from single-ended to differential operation by adding a second amplifier circuit that processes the complementary signal path. This dimensional expansion from one signal path to two differential paths enables true differential output capability, allowing the circuit to drive differential mixers effectively.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Reliability

If frequency doubler operates at high frequency, then the local oscillator quality is improved, but passive component performance degrades

Engineering Contradiction:

Improvelocal oscillator qualityVSAvoidpassive component performance degradation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces passive frequency multiplication components (such as nonlinear inductors or capacitors) with active differential amplifier circuits based on NMOS and PMOS transistors. This substitution of active devices for passive components enables high-frequency operation with better controlled gain and reduced sensitivity to passive component tolerances and losses.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

The proposed solution achieves a higher conversion gain and differential output, facilitating the generation of high-frequency local oscillators suitable for millimeter-wave transceivers, with improved power efficiency and reduced chip area, enabling effective driving of high-performance mixers.

Implementation Method 1

amplifies the amplitude of the second harmonic of the differential input signal

Methodology Applied

Scientific EffectSecond harmonic generation: Second Harmonic Generation

Implementation Method 2

Both the first and second differential amplifier circuit consist of multiple transistors; The voltage provider terminal VDD is used to provide driving current to thes e multiple transistors in the first and second differential amplifier circuit

Methodology Applied

Scientific EffectComplementary transistor operation:

Data Source

PatentUS11632090B1Push-push frequency doubling scheme and circuit based on complementary transistors

Publication Date: 2023.04.18 THE CHINESE UNIV OF HONG KONG (SHENZHEN)

AI summary

A push-push frequency doubler based on complementary transistors is provided. The first differential amplifier circuit receives a differential input signal having an initial frequency, and amplifies the amplitude of the second harmonic of the differential input signal to obtain a first signal. The second differential amplifier circuit receives the differential input signal with the initial frequency and amplifies the amplitude of the second harmonic of the differential input signal to obtain the second signal. Where, the first signal and the second signal are a set of differential signals with the same amplitude and a phase difference of 180°. The output load circuit extracts the second harmonic signal in the first and second signal respectively to obtain and output a pair of differential output signal with first output frequency whose value is twice of the initial frequency. As a result, the frequency doubler with differential output signal is realized.