GaN HEMT ESD Protection via Inductive Mediator
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Solution Overview
Problem
GaN-based HEMT devices used in electric power amplifiers for mobile phone base stations have insufficient tolerance to electrostatic discharge (ESD) breakdown, leading to reduced performance and increased costs due to the need for expensive ESD protection diodes, which also cause high-frequency loss and reduced power gain.
Innovation Solution
A semiconductor device configuration that includes a GaN-based HEMT chip and a pre-matching chip with a protective circuit featuring series-connected diodes and a low-pass filter, reducing the number of stages of protective diodes and minimizing parasitic resistance to achieve ESD breakdown protection without significant power gain reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ESD protection diodes are added to GaN-based HEMT devices, then tolerance to electrostatic discharge breakdown is improved, but high-frequency loss increases and power gain is reduced
Solution Approach 1:
A common ground inductor is introduced as an intermediary element between the ESD protection diodes and the signal path. This inductor acts as a mediator that blocks high-frequency signal currents from flowing through the ESD diodes while allowing DC protection currents to pass, thereby preventing high-frequency loss without compromising ESD protection capability
Solution Approach 2:
The ESD protection function is extracted and separated from the main signal path by connecting protection diodes to a dedicated ground reference point through an inductor, rather than directly to the signal line. This separation allows the protection mechanism to operate independently without interfering with the high-frequency signal transmission
2Reliability
If multiple stages of ESD protection diodes are used, then tolerance to electrostatic discharge breakdown is improved, but device complexity and cost increase
Solution Approach 1:
The invention changes the electrical parameters of the protection circuit by introducing an inductor with specific inductance value that creates frequency-dependent impedance. This parameter change allows a single stage of ESD diodes to provide adequate protection by blocking high-frequency signals through the inductor's impedance, eliminating the need for multiple cascaded diode stages
Solution Approach 2:
The common ground inductor serves multiple functions simultaneously: it provides the DC ground reference for ESD protection, blocks high-frequency signal leakage to protection diodes, and establishes the proper impedance for protection operation. This multi-functionality reduces the overall component count and circuit complexity
3Speed
If ESD protection diodes are connected directly to the gate terminal, then response speed to electrostatic discharge is improved, but parasitic resistance increases and power gain is reduced
Solution Approach 1:
The inductor acts as an intermediary that differentiates between DC protection currents and AC signal currents. For fast-acting ESD events, the inductor presents low DC resistance allowing immediate diode activation, while for continuous high-frequency signals, the inductor's reactive impedance blocks signal current, preventing power loss
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 configuration effectively provides ESD breakdown protection with a reduced number of series diodes, minimizing power gain loss and cost, making it suitable for high-frequency applications like mobile phone base station amplifiers.
Implementation Method 1
protective circuit featuring series-connected diodes and a low-pass filter
Implementation Method 2
insufficient tolerance to electrostatic discharge (ESD) breakdown
Data Source
AI summary
The present invention includes a first semiconductor chip, a second semiconductor chip, a first inductor, a second inductor, a second capacitor, protective diodes, and a third inductor. A field effect transistor includes a gate terminal, a drain terminal, and a source terminal connected to a ground terminal. The second semiconductor chip includes an input terminal and an output terminal connected in a direct current manner, and includes a first capacitor connected to the input terminal and to the ground terminal. The first inductor is connected between the output terminal and the gate terminal. The second inductor includes a first terminal connected to the input terminal. The second capacitor is connected between a second terminal of the second inductor and the ground terminal. Protective diodes are connected in series in a forward direction, and each has a cathode, and an anode connected to the ground terminal. The third inductor is connected between the cathode and the second terminal.