Compact Doherty Amplifier Layout for Stable Wide Video Bandwidth
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Solution Overview
Problem
Existing RF power amplifiers for mobile telecommunications base stations face challenges in achieving high efficiency and stability while minimizing footprint, leading to potential instability due to electromagnetic coupling and parasitic capacitances.
Innovation Solution
The amplifier design incorporates a package with a substrate and integrated high-power transistors, where passive semiconductor dies are used to integrate input and output matching capacitors and inductors, and electromagnetic coupling between inductors is intentionally introduced to mitigate coupling effects, enhancing stability and compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the amplifier footprint is reduced by integrating components, then compactness is improved, but electromagnetic coupling between components increases causing instability
Solution Approach 1:
The patent intentionally introduces electromagnetic coupling between the input and output inductors to counteract the harmful coupling between other components. By positioning the input inductor to electromagnetically couple with the output inductor, the harmful effects of parasitic capacitances and component coupling are converted into a beneficial stabilizing effect that improves amplifier reliability while maintaining compact integration.
Solution Approach 2:
The output resonance network acts as an intermediary element that mediates between the output matching capacitor and the high-power transistor. This resonance network, positioned between the output matching capacitor and the transistor, provides a controlled impedance path that reduces harmful electromagnetic coupling and parasitic effects, enabling stable operation in the compact integrated design.
2Ease of manufacture
If parasitic capacitances of the transistor are present, then transistor operation is enabled, but resonance at baseband frequencies occurs causing instability
Solution Approach 1:
The patent converts the harmful resonance effect of parasitic capacitances into a beneficial stabilizing mechanism. By intentionally designing the output resonance network to resonate at a frequency above the baseband, the parasitic capacitances are incorporated into a controlled resonance system that provides stability rather than causing harmful oscillations. The harmful parasitic effects are thus transformed into a useful stabilizing feature.
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 maintains amplifier stability and efficiency while reducing the footprint, achieving improved performance by closely integrating capacitors and inductors and using deep trench capacitors for resonance damping.
Implementation Method 1
an output resonance network that comprises a series connection of an inductor L3 and an output matching capacitor Cout. This network is configured such that at or close to the operational frequency of FET 3, the network behaves as an inductor that resonates with Cds.
Implementation Method 2
The parasitic capacitances Cgs, Cds resonate at a baseband frequency with the biasing line LGfeed and biasing line LDfeed, respectively
Implementation Method 3
The first and second deep trench capacitors have a first and second resonance frequency, respectively, that is below the baseband frequency range of the high-power transistor. The first and second deep trench capacitors have a quality factor, Q, of less than 10
Data Source
AI summary
Example embodiments relate to compact Doherty amplifiers having improved video bandwidth. One example embodiment includes an amplifier. The amplifier includes a package having a substrate. The amplifier also includes at least one amplifier unit arranged in the package. Each amplifier unit includes an input terminal and an output terminal. Each amplifier unit also includes an active semiconductor die on which a high-power transistor is integrated. Additionally, each amplifier unit includes an input matching capacitor and an output matching capacitor. Further, each amplifier unit includes a third inductor connecting an output of the high-power transistor to the output matching capacitor. In addition, each amplifier unit includes a fourth inductor connecting an input of the high-power transistor to the input matching capacitor. Yet further, each amplifier unit includes an output resonance network including a series connection of a first inductor and a first capacitor. Each amplifier unit includes a passive semiconductor die.