RF Amplifier Input Baseband Circuit for Resonance Suppression

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Solution Overview

Problem

Radio frequency (RF) power amplifiers face challenges in achieving improved baseband impedance and digital predistortion (DPD) linearity across a given band, with existing solutions often focusing on output-side enhancements and limited to narrowband applications, while resonances in baseband termination impede DPD operation.

Innovation Solution

Incorporating a baseband impedance enhancement circuit with reactive elements into the input matching network of RF power amplifiers, specifically using integrated passive devices (IPDs) to reduce resonances and enhance baseband impedance, allowing DPD to function effectively over wider bandwidths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If baseband termination is implemented in RF power amplifiers, then RF signal amplification is improved, but resonances occur that impede digital predistortion operation

Engineering Contradiction:

ImproveRF signal amplificationVSAvoidbaseband resonances

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

An input baseband enhancement circuit is introduced as an intermediary component between the baseband termination and the input matching network. This circuit contains resonant elements tuned to cancel the harmful baseband resonances generated by the termination, thereby eliminating the negative impact on digital predistortion while preserving RF amplification performance

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The harmful baseband resonances are converted into beneficial effects by designing the enhancement circuit with resonant elements that exploit the same resonant frequencies. The circuit transforms the problematic resonances into constructive impedance enhancement at baseband frequencies while maintaining RF performance

Inventive Principle:

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

2Reliability

If input and output impedance matching circuits are used to match RF power circuits to 50 ohm transmission lines, then impedance matching is improved, but baseband impedance performance deteriorates

Engineering Contradiction:

Improveimpedance matchingVSAvoidbaseband impedance

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The enhancement circuit applies localized impedance transformation specifically at the baseband frequency range without affecting the RF frequency matching. By using frequency-selective resonant elements, the circuit provides different impedance characteristics at different frequency bands, improving baseband impedance while maintaining RF impedance matching

Inventive Principle:

Principle #3Local quality

3Reliability

If conventional impedance matching circuits are implemented, then RF frequency matching is improved, but baseband impedance enhancement is limited to narrowband applications

Engineering Contradiction:

ImproveRF frequency matchingVSAvoidbandwidth

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The enhancement circuit uses dynamic impedance transformation through resonant elements that provide frequency-dependent impedance enhancement. This allows the circuit to adaptively improve baseband impedance across wide bandwidths rather than being fixed to narrowband operation, while maintaining RF frequency matching performance

Inventive Principle:

Principle #15Dynamics

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 significantly improves baseband impedance and DPD linearity, enabling effective operation across wider bandwidths, including the 2 GHz range and frequencies where LDMOS devices are not suitable, such as from 3 GHz to 5 GHz, with substantial improvements in instantaneous bandwidths over 160 MHz.

Implementation Method 1

the baseband impedance enhancement circuit is configured to reduce resonances of a baseband termination

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS11552597B2Radio frequency amplifier implementing an input baseband enhancement circuit and a process of implementing the same

Publication Date: 2023.01.10 MACOM TECH SOLUTIONS HLDG INC

AI summary

An amplifier includes an input matching network; at least one transistor; an input lead coupled to the at least one transistor; a ground terminal coupled to the transistor; an output lead coupled to the at least one transistor; an output matching circuit coupled to the output lead and to the at least one transistor; and a baseband impedance enhancement circuit having at least one reactive element coupled to the input matching network. The baseband impedance enhancement circuit is configured to reduce resonances of a baseband termination.