Doherty PA Output Combining Network Using Bond-Wire Phase Shift

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Solution Overview

Problem

Conventional Doherty power amplifier (PA) circuits face challenges in reducing transmission line losses and size, particularly at high RF frequencies, due to the use of lossy and lengthy planar transmission lines, which also increase complexity and cost.

Innovation Solution

The integration of a combining node within the Doherty PA device using die-to-die bond wires between carrier and peaking amplifier dies, along with a quarter wave transformer network, allows for efficient phase coherency and impedance transformation, reducing the need for downstream impedance matching and enabling a compact design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If planar transmission lines are used for signal transmission, then signal transmission is achieved, but transmission line losses increase and size increases

Engineering Contradiction:

Improvetransmission line lossesVSAvoidtransmission line length

Core Design Contradiction:

Loss of energyVSLength of stationary object

Solution Approach 1:

The patent merges the output combining network with the amplifier dies by integrating the combining node directly onto the peaking amplifier die. This eliminates the need for separate planar transmission lines to carry signals from the carrier amplifier to the combining node, thereby reducing transmission line losses and overall circuit size. The bond wires directly connect the carrier amplifier output to the combining node on the peaking amplifier die, removing lengthy transmission paths.

Inventive Principle:

Principle #5Merging (Combining)

2Device complexity

If planar transmission lines are used for impedance matching, then impedance matching is achieved, but device complexity increases

Engineering Contradiction:

Improvecircuit complexityVSAvoidmanufacturing simplicity

Core Design Contradiction:

Device complexityVSEase of manufacture

Solution Approach 1:

The patent combines multiple functions (amplification, combining, and impedance transformation) into integrated structures on the amplifier dies. The quarter wave transformer network is integrated directly onto the peaking amplifier die, eliminating the need for separate planar transmission line-based impedance matching circuits. This integration reduces device complexity and manufacturing steps while maintaining the required impedance matching functionality.

Inventive Principle:

Principle #5Merging (Combining)

3Volume of moving object

If separate amplifier dies are used for carrier and peaking amplifiers, then amplification functionality is achieved, but overall device size increases

Engineering Contradiction:

Improvedevice sizeVSAvoidamplification capability

Core Design Contradiction:

Volume of moving objectVSAdaptability or versatility

Solution Approach 1:

The patent merges the output combining network with the amplifier dies, integrating the combining node directly onto the peaking amplifier die. This eliminates the need for separate transmission lines and external combining circuits, thereby reducing overall device size while maintaining the dual-amplifier functionality. The compact integration achieves both size reduction and functional versatility.

Inventive Principle:

Principle #5Merging (Combining)

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 approach results in a significant size reduction of the Doherty PA circuit by up to 40%, improved bandwidth, and streamlined integration of harmonic termination circuits, while minimizing combining losses and enhancing efficiency.

Implementation Method 1

The at least one die-to-die bond wire has an electrical length resulting in a 90 degree phase shift imparted to the first amplified signal between the first output terminal and the combining node

Methodology Applied

Scientific EffectPhase shift:

Implementation Method 2

along with a quarter wave transformer network, allows for efficient phase coherency and impedance transformation

Methodology Applied

Scientific EffectImpedance transformation:

Data Source

PatentUS11190146B2Doherty power amplifier devices having intergrated output combining networks

Publication Date: 2021.11.30 NXP USA INC

AI summary

Doherty power amplifier (PA) devices (e.g., packages and modules) including integrated output combining networks are disclosed. In embodiments, the Doherty PA device includes a first amplifier die having a first transistor with a first output terminal at which a first amplified signal is generated, a second amplifier die having a second transistor with a second output terminal at which a second amplified signal is generated, and an output combining network. The output combining network includes, in turn, a combining node integrally formed with the second amplifier die and electrically coupled to the second output terminal. At least one die-to-die bond wire electrically couples the first output terminal to the combining node. The at least one die-to-die bond wire has an electrical length, which is results in a 90 degree phase shift imparted to the first amplified signal between the first output terminal and the combining node.