Transformer-Coupled RF Mixer With Shared Bias Current

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Solution Overview

Problem

Designing mixers for electronic devices with wireless communications capabilities that balance performance with minimized power consumption is challenging.

Innovation Solution

The implementation of a transformer-based mixer circuitry that shares a DC bias current between the transconductor and the switching quad, eliminating the need for different power supply voltages and thereby reducing power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If separate power supply voltages are used to bias the transconductor and switching quad, then each component can be optimized for its specific performance requirements, but the overall power consumption increases and device complexity increases

Engineering Contradiction:
Improveperformance optimizationVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent merges the biasing functions by connecting the center taps of both windings to a common bias current source, allowing a single power supply to provide bias current to both the transconductor and switching quad simultaneously, thereby reducing power consumption while maintaining performance

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The common bias current source serves multiple functions by providing bias current to both the transconductor and switching quad through the transformer's center taps, eliminating the need for separate biasing circuits and reducing overall device complexity

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If separate power supply voltages are used to bias the transconductor and switching quad, then each component can be optimized for its specific performance requirements, but the device complexity increases

Engineering Contradiction:
Improveperformance optimizationVSAvoidpower supply configuration
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the biasing functions by connecting the center taps of both windings to a common bias current source, allowing a single power supply to provide bias current to both the transconductor and switching quad simultaneously, thereby reducing power consumption while maintaining performance

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The common bias current source serves multiple functions by providing bias current to both the transconductor and switching quad through the transformer's center taps, eliminating the need for separate biasing circuits and reducing overall device complexity

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 solution enhances the linearity of the mixer while minimizing power consumption, achieving improved performance without increasing power usage.

Implementation Method 1

a transformer that couples an output of the transconductor to an input of the mixer transistors

Methodology Applied
Scientific EffectMagnetic coupling: Electromagnetic Induction

Data Source

PatentEP4521635A1Radio-frequency mixer with shared bias current
Publication Date: 2025.03.12 APPLE INC
  • EP4521635A1 patent drawingFigure 1
  • EP4521635A1 patent drawingFigure 2
  • EP4521635A1 patent drawingFigure 3

AI summary

An electronic device may include wireless circuitry with a mixer. The mixer may include a transconductor with first and second input transistors, a switching quad with first and second pairs of mixer transistors, and a transformer coupled between the transconductor and the switching quad. The transformer may have a primary winding and a secondary winding. The transformer may have a conductive path that couples a center tap contact of the primary winding to a center tap contact of the secondary winding. The conductive path may configure the transformer to share a DC bias current between the transconductor and the switching quad. This may eliminate the need to bias the transconductor and the switching quad using different power supply voltages, thereby minimizing power consumption without sacrificing performance.