MEMS Switch Die Logic Decoder for RF Signal Control
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Solution Overview
Problem
Current MEMS switches face challenges in efficiently integrating with semiconductor substrates to form compact digital logic circuits, particularly in radio frequency applications, due to limitations in reducing insertion losses and parasitic capacitance and inductance compared to silicon-on-insulator complementary metal oxide switches.
Innovation Solution
A microelectromechanical systems (MEMS) switch die with N number of RF MEMS switches, each having an anchored beam with a switch contact, a gate, and a terminal contact, is combined with a MEMS-based decoder to selectively open and close the switches using gate voltages, allowing for the realization of logic gates like inverter, NOR, NAND, and AND gates, reducing the need for multiple control lines and improving signal path efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If MEMS switches are used to replace FETs in signal path, then insertion losses and parasitic capacitance are reduced, but device complexity and integration with semiconductor substrates increases
Solution Approach 1:
The patent combines multiple RF MEMS switches and logic MEMS switches onto a single semiconductor substrate to form an integrated MEMS switch die. This merging approach reduces the need for external control logic and multiple discrete components, thereby addressing the integration complexity while maintaining the low insertion loss benefits of MEMS switches.
Solution Approach 2:
The invention implements logic gates using MEMS switches that can perform both switching and logic functions on the same substrate. This multi-functionality reduces the overall system complexity by eliminating separate control circuits, while preserving the low parasitic capacitance and insertion loss characteristics of MEMS technology.
2Ease of operation
If multiple control lines are used to control N number of RF MEMS switches, then individual switch control is achieved, but control line complexity and signal path length increases
Solution Approach 1:
The patent uses logic MEMS switches to decode control signals and generate the appropriate control voltages for each RF MEMS switch. This copying approach allows a single control input to be replicated and distributed to multiple switches through the logic gate network, reducing the number of independent control lines needed while maintaining individual switch control capability.
Solution Approach 2:
The logic MEMS switches act as intermediary components between the control input and the RF MEMS switches. These intermediaries decode the control signals and generate the necessary gate voltages, thereby reducing control line complexity while preserving the ability to individually control each RF MEMS switch.
3Device complexity
If FET switches are used in signal path, then device integration is simplified, but parasitic capacitance and inductance increase
Solution Approach 1:
The patent replaces FET-based electronic switching with MEMS mechanical switching. The MEMS switches use electrostatic actuation to physically open or close the signal path, eliminating the parasitic capacitance and inductance inherent in FET structures. The integration is achieved by fabricating the MEMS structures directly on the semiconductor substrate using compatible processes.
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 MEMS-based logic gates effectively decode signals to control RF MEMS switches, reducing insertion losses and parasitic effects, enabling more efficient and compact digital logic circuits with reduced control lines, thereby enhancing the performance in radio frequency applications.
Implementation Method 1
apply a higher level gate voltage to each gate of the RF MEMS switches determined to be closed, wherein the higher gate voltage electrostatically pulls the anchored beam and brings the switch contact into electrical contact with the terminal contact
Implementation Method 2
apply a lower gate voltage to each gate of the RF MEMS switches to be opened, wherein the lower gate voltage releases the anchored beam and allows the switch contact to break electrical contact with the terminal contact
Data Source
AI summary
A microelectromechanical systems (MEMS) switch die having an N number of radio frequency (RF) MEMS switches, each having a anchored beam with a switch contact, a gate, and a terminal contact is disclosed. Also included is a MEMS-based decoder having logic gates comprised of logic MEMS switches that are configured to decode the coded signals to determine which of the N number of RF MEMS switches to open and close, apply a higher level gate voltage to each gate of the RF MEMS switches determined to be closed, wherein the higher gate voltage electrostatically pulls the anchored beam and brings the switch contact into electrical contact with the terminal contact, and apply a lower gate voltage to each gate of the RF MEMS switches to be opened, wherein the lower gate voltage releases the anchored beam and allows the switch contact to break electrical contact with the terminal contact.