Monolithic Doherty Amplifier Combining Node Structure
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Solution Overview
Problem
Conventional Doherty power amplifiers face performance issues due to placement tolerances, wirebond length and height variations, and structural variations on printed circuit boards, leading to inconsistent RF performance in modern wireless communication systems requiring high integration and efficiency.
Innovation Solution
The integration of main and peaking amplifiers and a signal combiner within a single semiconductor die, with a high resistivity substrate and a conductive structure directly coupled to the peaking transistor's drain terminals, achieving a 90-degree phase difference using a CLC topology with wirebonds, which reduces tolerance in inductance value and minimizes losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If main and peaking amplifiers are implemented using discretely-packaged devices on a PCB substrate, then the amplifier can be constructed with separate components, but placement tolerances and wirebond variations lead to inconsistent RF performance
Solution Approach 1:
The patent integrates the main amplifier, peaking amplifier, and signal combiner into a single monolithic semiconductor die. This merging eliminates the separate PCB mounting and wirebond connections between discrete devices, thereby removing the source of placement tolerance issues and wirebond length/height variations that caused inconsistent RF performance.
2Reliability
If amplifiers are integrated on a single semiconductor die, then placement tolerance issues are eliminated, but the device complexity increases
Solution Approach 1:
The semiconductor die is segmented into distinct functional regions: a main amplifier section, a peaking amplifier section, and a signal combiner section. Each section is independently designed and optimized for its specific function, then integrated together. This segmentation allows complex functionality to be achieved while maintaining design clarity and manufacturing feasibility.
3Ease of manufacture
If wirebonds are used to connect amplifiers on a PCB, then electrical connections are established, but wirebond length and height variations cause performance inconsistencies
Solution Approach 1:
The patent extracts and eliminates the wirebond interconnection layer from the system architecture. By integrating all active components (main amplifier, peaking amplifier) and the signal combiner directly onto the same semiconductor die, the need for wirebonds to connect separate devices is removed entirely, eliminating the source of length and height variations.
4Ease of manufacture
If a conventional PCB-based combiner structure is used, then signal combining is achieved, but structural variations lead to performance issues
Solution Approach 1:
The signal combiner is merged with the amplifier sections and integrated directly into the semiconductor die structure. This integration ensures that the combiner's physical dimensions and electrical characteristics are precisely controlled by the semiconductor manufacturing process, eliminating the structural variations inherent in discrete PCB-based combiner implementations.
Data Source
AI summary
A multiple-path amplifier (e.g., a Doherty amplifier) includes a semiconductor die, a radio frequency (RF) signal input terminal, a combining node structure integrally formed with the semiconductor die, and first and second amplifiers (e.g., main and peaking amplifiers) integrally formed with the die. Inputs of the first and second amplifiers are electrically coupled to the RF signal input terminal. A plurality of wirebonds is connected between an output of the first amplifier and the combining node structure. An output of the second amplifier is electrically coupled to the combining node structure (e.g., through a conductive path with a negligible phase delay). A phase delay between the outputs of the first and second amplifiers is substantially equal to 90 degrees. The second amplifier may be divided into two amplifier portions that are physically located on opposite sides of the first amplifier.