RF Amplifier Output Impedance Matching Circuit Using Segmented Bondwires
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Solution Overview
Problem
Conventional RF amplifier devices face significant degradation in impedance transformation due to positive mutual inductance between bondwire arrays in output impedance matching circuits, which limits their performance in terms of impedance matching, bandwidth, gain, efficiency, and power capability.
Innovation Solution
Implementing a multi-segment inductance instead of a single bondwire array for the series inductance in the output impedance matching circuit, which reduces net mutual inductance between series and shunt inductances, effectively minimizing the phase offset and enhancing impedance matching within the package.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single bondwire array is used for series inductance in the output impedance matching circuit, then the device complexity is reduced, but the net mutual inductance between series and shunt inductances increases significantly, degrading impedance transformation
Solution Approach 1:
The series inductance is divided into multiple discrete bondwire arrays (first series bondwire array, second series bondwire array, etc.) instead of using a single bondwire array. This segmentation allows the net mutual inductance between series and shunt inductances to be reduced to near or below zero, significantly improving impedance transformation while maintaining manageable device complexity through systematic arrangement of the segmented elements.
2Ease of manufacture
If conventional bondwire arrays are used with significant inductive reactance, then the impedance matching circuit can be implemented within the package, but the positive mutual inductance between bondwire arrays significantly degrades the impedance transformation achievable
Solution Approach 1:
Different bondwire arrays are positioned and configured with specific local characteristics - the series bondwire arrays are arranged to provide series inductance while the shunt bondwire arrays provide shunt inductance. The local arrangement and orientation of these bondwire arrays are optimized to minimize positive mutual inductance between them, allowing in-package impedance matching to be achieved without significant degradation from mutual inductance effects.
3Device complexity
If the series inductance is implemented as a single bondwire array coupled between the transistor and output lead, then the circuit configuration is simplified, but the phase offset increases and bandwidth is limited
Solution Approach 1:
The series inductance is segmented into multiple bondwire arrays that can be independently optimized. This segmentation enables better control over the phase characteristics and reduces phase offset, thereby expanding the operational bandwidth of the RF amplifier device while maintaining a relatively simple overall circuit configuration.
4Ease of manufacture
If positive mutual inductance between series and shunt bondwire arrays is present, then the bondwire arrays can be used for both series and shunt inductance, but the impedance transformation achievable by the output impedance matching circuit is significantly degraded
Solution Approach 1:
The series inductance is divided into multiple discrete bondwire arrays, allowing independent optimization of each array's position and configuration. This segmentation enables the maintenance of practical manufacturing simplicity while achieving precise impedance matching by minimizing the net mutual inductance between series and shunt inductances to near or below zero.
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 approach significantly increases the real part of the output impedance, improves bandwidth, gain, and efficiency, and allows for higher power capability within a given power transistor footprint, while maintaining a smaller phase offset, thus enhancing the overall performance of RF amplifier devices.
Implementation Method 1
positive mutual inductance between the series bondwire array and the shunt bondwire array may significantly degrade the impedance transformation achievable by an output impedance matching circuit
Data Source
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AI summary
A packaged RF amplifier device includes a transistor and an output circuit. The transistor includes a control terminal and first and second current carrying terminals. The output circuit is coupled between the first current carrying terminal and an output lead. The output circuit includes first and second inductive elements coupled in series. The first inductive element, which may be a first bondwire array or an integrated inductance, is coupled between the first current carrying terminal and a node. The second inductive element, which includes a second bondwire array, is coupled between the node and the output lead. The device also includes a shunt circuit with a shunt capacitor and a third bondwire array coupled between the first current carrying terminal and the shunt capacitor. The first and second inductive elements and the third bondwire array are configured to have a desired mutual inductance.