Split Bondwire Arrays for RF Amplifier Mutual Inductance Reduction
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Solution Overview
Problem
Mutual inductance between bondwire arrays in RF power amplifier circuits affects the performance and operating characteristics, leading to challenges in output matching network design and impedance transformation.
Innovation Solution
The use of a 'split' bondwire array arrangement, where additional bondwires connect the output shunt capacitor's terminal to ground, creating effective negative mutual inductance and improving impedance transformation, thereby reducing the need for a bondback matching network and increasing reliability by eliminating through-substrate vias.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional bondwire arrays are used to connect output shunt capacitor to ground, then mutual inductance between bondwire arrays increases, but device complexity and reliability decrease
Solution Approach 1:
The bondwire array is segmented into multiple subsets arranged in parallel, with each subset containing bondwires that connect the output shunt capacitor terminal to ground. This segmentation reduces mutual inductance between individual bondwires by increasing spatial separation and distributing current paths, thereby eliminating the need for additional bondback matching networks while improving device reliability
Solution Approach 2:
Instead of connecting the output shunt capacitor terminal directly to ground through a single bondwire array, the invention inverts the approach by using multiple parallel bondwire arrays that collectively provide the ground connection. This inverted architecture transforms the mutual inductance problem into a beneficial distributed structure that improves impedance matching without requiring additional matching networks
2Object-affected harmful factors
If additional bondwires are added to create split bondwire array, then mutual coupling between bondwire arrays reduces, but manufacturing complexity increases
Solution Approach 1:
Multiple bondwire arrays are merged in parallel configuration to form a unified ground connection structure for the output shunt capacitor. This merging approach reduces mutual coupling between individual bondwires while maintaining manufacturing simplicity, as all bondwires perform the same function and can be installed using standard bonding processes without requiring complex alignment or additional fabrication steps
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 arrangement reduces mutual coupling between bondwire arrays, enhances impedance matching, and improves isolation, potentially eliminating the need for additional matching networks and increasing the reliability of the device.
Implementation Method 1
These bondwire arrays act as inductors and some are designed to be part of the input and output passive circuits associated with for example a packaged RF transistor. These bondwire arrays interact with one another due to mutual inductance which affects the characteristics of the circuits using the bondwire arrays.
Implementation Method 2
The use of a 'split' bondwire array arrangement, where additional bondwires connect the output shunt capacitor's terminal to ground, creating effective negative mutual inductance and improving impedance transformation
Data Source
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AI summary
Various embodiments relate to a packaged radio frequency (RF) amplifier device implementing a split bondwire where the direct ground connection of an output capacitor is replaced with a set of bondwires connecting to ground in a direction opposite to the wires connecting to the output of a transistor to an output pad. This is done in order to reduce the effects of mutual inductance between the various bondwires associated with the output of the RF amplifier device.