Differential Mixer Circuit with Passive V-I Conversion for Linearity

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Solution Overview

Problem

Existing frequency mixer circuitry, particularly in integrated form, faces limitations in speed, linearity, and dynamic range due to the use of transistors for voltage-to-current conversion, which affects the performance in receiver and transmitter applications.

Innovation Solution

The implementation of a differential mixer circuitry using a passive network of impedances, such as resistors and inductors, for voltage-to-current conversion, eliminating the need for transistors and enhancing matching with preceding stages, along with a mixing stage that mixes differential input-current signals with a mixing signal to produce an output signal with a frequency dependent on the input and mixing frequencies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If transistors are used for voltage-to-current conversion in mixer circuitry, then the conversion function is achieved, but speed and linearity are limited

Engineering Contradiction:
Improvemixer speedVSAvoidtransistor-based conversion circuit
Core Design Contradiction:
SpeedVSDevice complexity

Solution Approach 1:

The patent replaces the transistor-based voltage-to-current conversion mechanism with a passive impedance network (resistors and inductors). This substitution eliminates the limitations of transistor switching speed and non-linearity, achieving faster and more linear conversion. The passive network directly converts the differential input voltage signal to a differential input current signal without requiring active transistor components.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If transistors are used for voltage-to-current conversion, then conversion is achieved, but dynamic range is reduced

Engineering Contradiction:
Improvedynamic rangeVSAvoidtransistor-based conversion circuit
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the transistor-based voltage-to-current conversion mechanism with a passive impedance network (resistors and inductors). This substitution eliminates the limitations of transistor switching speed and non-linearity, achieving faster and more linear conversion. The passive network directly converts the differential input voltage signal to a differential input current signal without requiring active transistor components.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If transistors are used for voltage-to-current conversion, then conversion function is provided, but matching with preceding stages is poor

Engineering Contradiction:
Improveimpedance matchingVSAvoidtransistor-based conversion circuit
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces the transistor-based voltage-to-current conversion mechanism with a passive impedance network (resistors and inductors). This substitution eliminates the limitations of transistor switching speed and non-linearity, achieving faster and more linear conversion. The passive network directly converts the differential input voltage signal to a differential input current signal without requiring active transistor components.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP3840220A1Mixer circuitry
Publication Date: 2021.06.23 SOCIONEXT INC
  • EP3840220A1 patent drawingFigure 1A~1B
  • EP3840220A1 patent drawingFigure 2
  • EP3840220A1 patent drawingFigure 3

AI summary

Differential mixer circuitry comprising: first and second input-voltage nodes and first and second input-current nodes; a passive network of impedances connected between the first and second input-voltage nodes and the first and second input-current nodes, and configured to convert first and second input-voltage signals received at the first and second input-voltage nodes, respectively, into first and second input-current signals provided at the first and second input-current nodes, respectively, the first and second input-voltage signals defining a differential input-voltage signal having an input frequency, and the first and second input-current signals defining a differential input-current signal; and a mixing stage configured to mix the differential input-current signal with at least one mixing signal having a corresponding mixing frequency and output a differential output signal having an output frequency dependent on the input frequency and each mixing frequency.