SOI RF Switch Charge Injection Control in Stacked Transistors
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Solution Overview
Problem
Charge injection is a significant issue in semiconductor-on-insulator (SOI) radio frequency (RF) switches, leading to performance degradation, nonlinear switch response, and undesirable RF harmonics generation.
Innovation Solution
A novel circuit and method for controlling charge injection in SOI RF switches, which includes a plurality of switching transistors connected in series with charge injection control elements. These control elements receive injected charge from resistively-isolated nodes and convey it to non-isolated nodes, optionally switching between ON and OFF states based on a control signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If charge injection control elements are added to SOI RF switches, then linearity and reliability are improved, but device complexity increases
Solution Approach 1:
Charge injection control elements are introduced as intermediary components between the switching transistors and resistively-isolated nodes. These control elements actively manage charge accumulation by providing controlled charge transfer paths, thereby improving switch reliability and linearity without requiring fundamental changes to the SOI RF switch architecture.
Solution Approach 2:
The invention modifies the electrical parameters of the SOI RF switch by introducing controllable charge transfer mechanisms. By dynamically adjusting charge distribution through the control elements, the system achieves improved linearity and reliability while maintaining compatibility with existing switch designs.
2Speed
If switching transistors are used in SOI RF switches, then switching speed is improved, but charge injection effects worsen
Solution Approach 1:
The invention converts the harmful charge injection effect into a beneficial phenomenon by introducing control elements that deliberately manage charge transfer. These elements use controlled charge injection mechanisms to neutralize unwanted charge accumulation, thereby maintaining fast switching speeds while eliminating nonlinear distortion and RF harmonics generation.
3Reliability
If resistively-isolated nodes are used in SOI RF switches, then switch isolation is improved, but charge accumulation increases
Solution Approach 1:
Charge injection control elements are positioned as intermediary components connected to resistively-isolated nodes. These control elements provide controlled charge transfer paths that prevent charge accumulation while preserving the high isolation characteristics of the resistively-isolated nodes. The control elements act as charge sinks or sources that balance charge distribution.
Data Source
AI summary
A circuit and method for controlling charge injection in a circuit are disclosed. In one embodiment, the circuit and method are employed in a semiconductor-on-insulator (SOI) Radio Frequency (RF) switch. In one embodiment, an SOI RF switch includes switching transistors coupled in series, referred to as “stacked” transistors, and implemented as a monolithic integrated circuit on an SOI substrate. Charge injection control elements are coupled to receive injected charge from resistively-isolated nodes located between the switching transistors, and to convey the injected charge to at least one node that is not resistively-isolated. The charge injection control elements include resistors or transistors. A method for controlling charge injection in a switch circuit is disclosed whereby injected charge is generated at resistively-isolated nodes between series coupled switching transistors, and the injected charge is conveyed to at least one node of the switch circuit that is not resistively-isolated.