Transformer-Coupled RF Switch Layout for ESD Current Shunting
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Solution Overview
Problem
Wireless devices with shared antennas for time division duplexing are susceptible to damage from electrostatic discharge (ESD) events, which can rupture the gate oxide of switches, leading to manufacturing failures and operational issues.
Innovation Solution
A transceiver chip design that includes a power amplifier, a transformer, a switch, a shunt inductor, and clamp circuits to provide ESD protection by shunting ESD current around the switch and limiting voltage between critical components to prevent gate oxide breakdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a switch is used to switch between transmit mode and receive mode in a wireless device with shared antenna, then the device can share the antenna effectively, but the switch becomes susceptible to damage from electrostatic discharge (ESD) events
Solution Approach 1:
A diode is introduced as an intermediary component between the switch and the antenna pad. The diode acts as a mediator that captures and redirects ESD current away from the switch, allowing the switch to perform its antenna sharing function while the diode protects it from ESD damage.
Solution Approach 2:
The diode is positioned to intentionally intercept the harmful ESD current, converting the potentially damaging event into a controlled path where the ESD energy is dissipated through the diode's forward bias connection to ground, thereby protecting the switch.
2Reliability
If ESD protection components are added to protect the switch, then the reliability against ESD improves, but the device complexity increases
Solution Approach 1:
The diode serves multiple functions: it provides ESD protection by capturing discharge current, and its forward bias connection to ground also serves as a reference potential for the switch operation. This multi-functionality reduces the need for additional separate components.
Solution Approach 2:
The diode is a simple, inexpensive component that can be easily replaced if needed. Its use as a sacrificial protection element is cost-effective compared to using more complex or expensive protection circuits, and the diode's simplicity minimizes the increase in device complexity.
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 effectively prevents ESD-induced damage to the switch and low-noise amplifier, enhancing the robustness of the chip during ESD events and improving manufacturing yields by providing a safe discharge path and voltage clamping.
Implementation Method 1
The switch may be susceptible to damage from an electrostatic discharge (ESD) event. The solution effectively prevents ESD-induced damage to the switch and low-noise amplifier, enhancing the robustness of the chip during ESD events by providing a safe discharge path
Implementation Method 2
A first aspect relates to a chip. The chip includes a pad, and a power amplifier having a first output and a second output. The chip also includes a transformer, wherein the transformer includes a first inductor coupled between a first terminal and a second terminal of the transformer
Data Source
AI summary
In certain aspects, a chip includes a pad, and a power amplifier having a first output and a second output. The chip also includes a transformer, wherein the transformer includes a first inductor coupled between a first terminal and a second terminal of the transformer, wherein the first terminal is coupled to the first output of the power amplifier, and the second terminal is coupled to the second output of the power amplifier. The transformer also includes a second inductor coupled between a third terminal and a fourth terminal of the transformer, wherein the third terminal is coupled to the pad. The chip also includes a first switch coupled to the fourth terminal, a shunt inductor coupled in parallel with the first switch, and a low-noise amplifier coupled to the third terminal.