RF Amplifier Output Circuit with Integrated Current Path
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Solution Overview
Problem
Conventional high-power RF transistor devices have limited instantaneous signal bandwidth due to low frequency resonance caused by interactions between bias feeds and baseband decoupling circuit components, restricting their ability to support wider RF bandwidth amplifiers.
Innovation Solution
Incorporating a multi-dielectric ceramic device with a current path structure that circumscribes low-Q material, reducing eddy currents and power losses, and using a baseband decoupling circuit with high capacitance values to increase low frequency resonance and instantaneous signal bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional baseband decoupling circuits are used, then device structure is simple, but instantaneous signal bandwidth is limited due to low frequency resonance
Solution Approach 1:
The baseband decoupling circuit is segmented into multiple discrete capacitors (first baseband decoupling capacitor and second baseband decoupling capacitor) with different capacitance values, allowing each capacitor to target specific frequency ranges and reduce low frequency resonance effects while maintaining overall circuit functionality
Solution Approach 2:
The invention changes the capacitance parameters by using capacitors with different capacitance values (first capacitance value and second capacitance value) to create a decoupling circuit that effectively operates across a broader frequency range, thereby increasing instantaneous signal bandwidth
2Device complexity
If lossy materials are placed between current paths, then device structure is simple, but power losses increase due to eddy currents
Solution Approach 1:
The invention extracts and removes the lossy material from between the forward and reverse current paths, eliminating the source of eddy current losses while maintaining the structural simplicity of the device through alternative current path routing
Solution Approach 2:
The invention introduces an intermediary current path structure that routes currents around the lossy material region, using intermediate conductive paths to transfer energy without direct contact with the lossy material, thereby reducing eddy current generation
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
The solution enables RF amplifiers to achieve wider RF bandwidths, supporting transmission of signals with ISBW of 200 MHz or above and LFR of approximately 600 MHz or greater, while minimizing power losses through the elimination of lossy materials between current paths.
Implementation Method 1
a current path structure configured to circumscribe the relatively low-Q material of Cenv
Implementation Method 2
the ISBW of the device is limited by the low frequency resonance (LFR) caused by interaction between the device's bias feeds and components of such a baseband decoupling circuit
Data Source
AI summary
A device includes multiple ceramic capacitors and a current path structure. A first ceramic capacitor includes a first ceramic material between first and second electrodes. A second ceramic capacitor includes a second ceramic material between third and fourth electrodes. The second ceramic material has a higher Q than the first ceramic material. The current path structure includes a lateral conductor located between the first and second ceramic materials, and first and second vertical conductors that extend from first and second ends of the lateral conductor to a device surface. The device may be coupled to a substrate of a packaged RF amplifier device, which also includes a transistor. For example, the device may form a portion of an output impedance matching circuit coupled between a current carrying terminal of the transistor and an output lead of the RF amplifier device.