Variable Termination Circuit for Balun Amplitude-Phase Imbalance

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Solution Overview

Problem

Existing digital-to-analog converters (DACs) and analog-to-digital converters (ADCs) suffer from significant even-order distortion due to amplitude/phase imbalance introduced by baluns, which degrade their performance.

Innovation Solution

A termination circuit with an amplitude and phase imbalance-tuning technique (APIT) that includes on-chip variable termination circuits with reconfigurable tuning circuits, capable of adapting to either amplitude or phase tuning, to compensate for imbalance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a balun is used to transform differential signals into single-ended signals, then insertion loss is reduced, but amplitude/phase imbalance is introduced which causes even-order distortion

Engineering Contradiction:

Improveinsertion lossVSAvoideven-order distortion

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary termination circuit with tuning circuits between the balun and the DAC/ADC. This intermediary circuit compensates for the amplitude and phase imbalance introduced by the balun, thereby reducing even-order distortion while maintaining the low insertion loss benefit of using a balun.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs tuning circuits that can dynamically adjust electrical parameters (such as resistance, capacitance, or inductance) to compensate for amplitude and phase imbalance. By changing these parameters, the system optimizes signal balance and reduces distortion without sacrificing the low insertion loss characteristic of the balun.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If fixed termination circuits are used, then circuit complexity is reduced, but adaptability to different signal conditions is limited

Engineering Contradiction:

Improvecircuit complexityVSAvoidadaptability to signal conditions

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent transitions from fixed termination circuits to dynamic, tunable termination circuits. The tuning circuits can adjust their characteristics in real-time to adapt to different signal conditions, improving versatility while maintaining manageable complexity through systematic design.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The termination circuit is designed with multi-functional tuning capabilities that can handle various signal conditions and imbalance scenarios. This universal design allows the same circuit structure to adapt to different operating conditions without requiring multiple specialized circuits.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS20250253823A1Termination circuit with amplitude and phase imbalance-tuning technique

Publication Date: 2025.08.07 MEDIATEK INC

AI summary

An on-chip variable termination circuit includes a plurality of first tuning circuits and a plurality of second tuning circuits. Each of the first tuning circuits is coupled between a positive signal node of a differential signal port and a voltage node. The first tuning circuits include at least one amplitude tuning circuit and at least one phase tuning circuit. Each of the second tuning circuits is coupled between a negative signal node of the differential signal port and the voltage node. The second tuning circuits include at least one amplitude tuning circuit and at least one phase tuning circuit.