SOI RF Switch Body Bias Circuit for Leakage and Harmonics
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Mobile RF transceivers using SOI technology face challenges with the floating body effect, leading to parasitic transistors, OFF-state leakage, and generation of out-of-band harmonics, which degrade device performance and hinder communication enhancements.
Innovation Solution
A dynamic bias control circuit is implemented, comprising transistors coupled to the gate and body regions of a switch FET with resistors and capacitors, dynamically biasing the body to improve breakdown voltage and harmonic performance, reducing real loss and optimizing chip area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SOI technology is used to reduce parasitic device capacitance, then device isolation is improved, but the floating body effect causes OFF-state leakage and out-of-band harmonics
Solution Approach 1:
A dynamic body bias control circuit is introduced as an intermediary between the body terminal and ground. This circuit includes a control transistor that dynamically adjusts the body bias voltage based on the switch state, effectively mediating the floating body effect and preventing charge accumulation that causes leakage and harmonics
Solution Approach 2:
The body bias voltage is changed from a static connection to a dynamically controlled voltage. The control transistor adjusts the body bias in real-time according to the switch state, making the system adaptive and preventing the floating body effect during critical operating conditions
2Object-generated harmful factors
If a thicker BOX layer is used to reduce artificial harmonics, then harmonic performance is improved, but parasitic device capacitance increases
Solution Approach 1:
Instead of changing the physical parameter of BOX layer thickness, the patent changes the electrical parameter of body bias voltage. By dynamically adjusting the body bias voltage, the patent achieves harmonic suppression without modifying the physical structure, thereby avoiding increased parasitic capacitance
3Loss of energy
If device isolation is increased to reduce RF loss, then RF performance is improved, but the floating body effect becomes more pronounced
Solution Approach 1:
The dynamic body bias control circuit serves as an intermediary that actively manages charge in the body region. By providing a controlled path for charge discharge through the control transistor, it prevents charge accumulation that would otherwise worsen with increased device isolation
Data Source
AI summary
A radio frequency (RF) device is described. The RF device includes a switch field effect transistor (FET), having a source region, a drain region, a body region, and a gate region. The RF device also includes a dynamic bias control circuit. The dynamic bias control circuit includes a first transistor coupled to the gate region of the switch FET by a gate resistor. The dynamic bias control circuit also includes a second transistor coupled to the first transistor and coupled to the body region of the switch FET by a body resistor. The dynamic bias control circuit further includes a capacitor coupled to the body region of the switch FET by the body resistor, and the gate region of the switch FET, by the gate resistor.