SJT Si-MESFETTM Benefits the Designer and End User:
Easy Implementation with existing SOI CMOS
Helps Combat Obsolescence
Simpler RF PA Development
The Problem: High Voltage (>2V) is Difficult on Modern CMOS
Original equipment designers are challenged by rapid technological obsolescence and increasingly smaller system packaging, driving the search for new, innovative technologies that can reduce physical footprints on printed circuit boards and operate at higher efficiencies to increase battery life. These technologies must also reduce total manufacturing costs and improve reliability.
Micropower circuits are used primarily for analog applications yet they can be manufactured inexpensively using CMOS foundries designed for digital circuits. However, as digital CMOS continues to scale, the constraints placed on micropower analog circuit design become ever more challenging. Chief amongst these is the continuing reduction in supply voltage. Today’s digital circuits operate with supply voltages of 1.2V and the International Technology Roadmap for Semiconductors (‘Roadmap’ for short) has this falling to 1V by 2013.
Even for CMOS foundries with precision analog capability the supply voltage is 2.5V today falling to 1.8V by 2013. Although low voltage operation generally equates to low power consumption, it can come at the price of reduced power efficiency. At the same time there are numerous analog circuits where an inductive load induces a ‘back-emf’ that is 2-4 times larger than the nominal operating voltage. For these circuits the only way to prevent CMOS transistors from being destroyed is to reduce the supply voltage still further.
The Solution - Patented Si-MESFETTM Enables High Voltage and RF Performance
SJT Micropower has patented methods for fabricating metal-semiconductor field-effect transistors (MESFETs) that are a high voltage (5-50V) alternative to CMOS. The MESFETs are fabricated using existing SOI CMOS foundries with no additional processing steps making them extremely cost effective.
The MESFETs can withstand voltages that would destroy conventional digital CMOS transistors and are capable of ultra-low power operation at radio frequencies (RF) making them ideally suited to high speed switching applications. As CMOS continues to scale, the maximum voltage conventional transistors can withstand will continue to decrease making RF analog design increasingly difficult with future technologies.
Our added value is that engineers will be able to continue high-speed/high-voltage design on CMOS processes by using our patented silicon MESFETs. The demand for our technologies will continue to increase as the industry pushes to smaller technologies and increase their use of SOI substrates.
Figure 1. Family of curves showing higher voltage operation on a scaled technology with maximum CMSO MOSFET voltage of 2V. The MESFET shows soft breakdown at 10V. No additional process steps were needed to achieve higher voltage operation.
Figure 2. Die Micrograph of fabricated Si-MESFETs showing DC and GSG structures.
There are many opportunities including efficient power regulation modules, RF power amplifiers and radiation hardened electronics that can take advantage of our technology.
Key Technology Enablers
- Add to SOI CMOS with No Additional Cost
- High Voltage Devices
- Depletion Mode Operation
- GHz Device Operation
- Robust Gate
- Cadence Based Models