Differential Doherty Amplifier Layout for Smaller RF Modules
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Solution Overview
Problem
The existing Doherty amplifier circuit configurations for RF modules result in increased die size of HBT devices and RF module substrates, limiting miniaturization potential.
Innovation Solution
A differential Doherty amplifier circuit design where the first and second differential amplifiers, along with their respective peak and carrier amplifiers, are formed on a chip device parallel to the XY plane, with specific wiring lines and components strategically positioned to overlap or not overlap with the chip device mounting region, allowing for reduced die and substrate sizes through flip-chip mounting and multilayer substrate configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If individual components of a Doherty amplifier circuit are disposed on a die of an HBT device, then the amplifier circuit can be integrated, but the die size of the HBT device increases
Solution Approach 1:
The amplifier circuit is divided into two separate parts: differential amplifiers formed on the HBT device die and inductors formed on the substrate. This segmentation allows the die size to be reduced while maintaining circuit integration through the connection of these separated components via wiring lines.
Solution Approach 2:
The circuit components are distributed across different spatial dimensions - the differential amplifiers are placed on the die surface parallel to the XY plane, while the inductors are formed on the substrate in the Z direction. This three-dimensional arrangement reduces the two-dimensional footprint on the die.
2Ease of manufacture
If individual components of a Doherty amplifier circuit are disposed on a die of an HBT device, then the amplifier circuit can be integrated, but the size of the RF module substrate increases
Solution Approach 1:
By segmenting the circuit into differential amplifiers on the die and inductors on the substrate, the substrate only needs to accommodate the inductor components and their connections, significantly reducing the required substrate area compared to placing all components on the substrate.
Solution Approach 2:
The wiring lines that connect the differential amplifiers to the inductors are made to overlap with the region where the chip device is mounted. This merging of connection paths with the mounting region eliminates the need for separate routing areas on the substrate, reducing overall substrate size.
3Reliability
If wiring lines are extended beyond the chip device mounting region, then connections can be established, but the substrate area increases
Solution Approach 1:
The wiring lines are routed in the Z direction (vertical dimension) by forming them on the substrate beneath or above the chip device mounting region, rather than extending in the XY plane. This allows connections to be established without increasing the footprint area of the substrate.
Solution Approach 2:
The wiring lines are positioned to overlap with and be nested within the vertical projection of the chip device mounting region. The wiring lines in the substrate are aligned with the mounting region above, creating a nested arrangement that minimizes substrate area usage.
Data Source
AI summary
A differential Doherty amplifier circuit includes a first differential amplifier including a first carrier amplifier and a second carrier amplifier, a second differential amplifier including a first peak amplifier and a second peak amplifier, a first line connected to the first carrier amplifier and the first peak amplifier, and a second line connected to the second carrier amplifier and the second peak amplifier. The first differential amplifier and the second differential amplifier are formed on a die of a chip device parallel to an XY plane. The first line and the second line are each formed of a wiring line disposed in a substrate parallel to the XY plane. The chip device is flip-chip mounted on the substrate in a Z direction orthogonal to the XY plane.