Stacked Doherty Amplifier Layout for Stable High-Frequency Feedback
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Solution Overview
Problem
Existing high frequency amplifiers face challenges in reducing size and stability due to the mounting of driver, carrier, and peak amplifiers on the same plane, leading to instability and increased size requirements.
Innovation Solution
A two-stage structure is employed with the driver amplifier on a separate substrate stacked on a first substrate, where the electrical length between the input terminal of the driver amplifier and the output terminal of the carrier amplifier is set to (2n+1)π, and a grounded metal layer is used to minimize electromagnetic interference, along with phase adjustment to stabilize the amplifier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If driver amplifier, carrier amplifier, and peak amplifier are mounted on the same plane, then ease of manufacture is improved, but device area increases and stability deteriorates
Solution Approach 1:
The patent transitions from a two-dimensional planar arrangement to a three-dimensional stacked configuration. The driver amplifier is mounted on a first substrate while the carrier and peak amplifiers are mounted on a second substrate positioned above the first substrate. This vertical stacking reduces the horizontal device area while maintaining ease of manufacture through standardized multi-layer PCB technology.
2Ease of manufacture
If driver amplifier, carrier amplifier, and peak amplifier are mounted on the same plane, then ease of manufacture is improved, but stability deteriorates
Solution Approach 1:
By separating the driver amplifier on the first substrate from the carrier and peak amplifiers on the second substrate, the patent reduces electromagnetic interference and signal feedback issues that cause instability in planar configurations. The vertical separation improves stability while maintaining manufacturing simplicity.
Solution Approach 2:
The patent introduces a grounded metal layer between the first substrate (driver amplifier) and the second substrate (carrier and peak amplifiers). This grounded layer acts as an intermediary that shields against electromagnetic interference and prevents signal feedback, thereby improving stability without compromising ease of manufacture.
3Area of stationary object
If two-stage structure with stacked substrates is used, then device area is reduced and stability is improved, but electromagnetic interference occurs between substrates
Solution Approach 1:
The grounded metal layer positioned between the first substrate and second substrate serves as an electromagnetic shield. It blocks harmful electromagnetic fields from passing between the substrates, eliminating the interference problem while maintaining the compact stacked structure.
Solution Approach 2:
The patent extracts the electromagnetic interference problem by introducing a dedicated grounded shielding layer that absorbs and redirects electromagnetic energy away from sensitive amplifier circuits, allowing the compact stacked design to function without interference.
Data Source
AI summary
A high frequency amplifier includes a Doherty amplifier including a carrier amplifier and a peak amplifier; a driver amplifier; a branch circuit configured to branch a signal amplified by the driver amplifier into input paths on a peak amplifier side and on a carrier amplifier side; and a phase adjustment circuit provided on a path on the peak amplifier side or on the carrier amplifier side. An electrical length from an input terminal of the driver amplifier to an output terminal of the carrier amplifier through the driver amplifier, the branch circuit, the input path on the carrier amplifier side, and the carrier amplifier is set such that a phase difference between a signal input to the driver amplifier without passing through the carrier amplifier and a signal fed back to the driver amplifier from the output terminal of the carrier amplifier is in a negative feedback region.