RF Antenna Switch Stack Layout for Uniform Transistor Voltage
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Solution Overview
Problem
Existing radio frequency antenna switches face reliability issues due to uneven voltage distribution among stacked transistors, leading to poor transistor reliability and increased costs from additional passive devices or signal paths, which result in performance deterioration.
Innovation Solution
The radio frequency antenna switch employs a stack manner with transistors having progressively decreasing channel width to length ratios and resistance values, or metal wire coverage areas, to ensure even voltage distribution and improved reliability, without introducing extra passive devices or signal paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple transistors are stacked in a branch to improve voltage distribution and reliability, then transistor reliability is improved, but uneven voltage distribution among the stacked transistors occurs due to gate and body current leakages
Solution Approach 1:
The patent applies local quality by making different parts of the transistor structure have different properties. Specifically, the gate and body regions are doped with different types and concentrations of impurities (e.g., p-type doping in gate region, n-type in body region) to create localized electrical characteristics that compensate for the inherent current leakage paths, thereby achieving more uniform voltage distribution across stacked transistors
Solution Approach 2:
The patent changes physical parameters of the transistor structure, particularly doping concentrations and types in different regions. By adjusting the impurity concentration profiles in gate, body, and channel regions, the electrical characteristics are modified to reduce gate-to-body current leakage and achieve more uniform voltage distribution among stacked transistors operating in high-voltage swing conditions
2Manufacturing precision
If additional passive devices or coupled circuits are added to balance voltage distribution among stacked transistors, then voltage distribution uniformity is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the need for external passive balancing devices (such as gate resistors, body resistors, or coupling capacitors) by incorporating the voltage distribution balancing function directly into the transistor structure itself through specialized doping profiles. This internal integration removes the need for additional circuit elements while achieving the desired voltage uniformity
Solution Approach 2:
The patent merges the voltage distribution balancing function with the transistor's inherent structure by combining the impurity doping design with the transistor operation. The doping structure itself performs the voltage balancing function that would otherwise require separate passive components, thereby simplifying the overall circuit architecture
3Manufacturing precision
If additional coupled circuits or passive devices are introduced to balance voltage distribution, then voltage distribution uniformity is improved, but insertion loss increases and performance deteriorates
Solution Approach 1:
The patent removes the need for additional passive balancing components that would introduce energy loss. By achieving voltage distribution uniformity through intrinsic transistor doping structures rather than external resistors or capacitors, the solution eliminates the parasitic losses associated with those components while maintaining low insertion loss
Data Source
AI summary
A radio frequency antenna switch includes an antenna port, a radio frequency signal port, and at least one branch connected to the antenna port or the radio frequency signal port, where each branch includes multiple transistors which are connected in a stack manner; channel width to length ratios of a preset number of transistors in the multiple transistors progressively decrease in a direction away from the antenna port, where the preset number is less than or equal to the total number of the multiple transistors. With the radio frequency antenna switch, capacitances of the preset number of transistors close to the antenna port increase, and distributed voltages that these transistors close to an antenna end in an off state need to bear are reduced.