This presentation shows how various CMOS components can be replaced using MEMS technology for higher power efficiency.

1. MEMS SWITCHES AS AN
ALTERNATIVE TO CMOS
TECHNOLOGY
DEVANG SANKHALA
DGS150030
4/11/2016

2. INTRODUCTION
• Switches are easy to use: push, toggle or turn. But
they are BIG.
• Transistors are used to scale down electronics devices
and make them lighter, power efficient and easy to
use

3. MOTIVATION
Transistors have leakage
resistances and capacitances.
They become less efficient
and consume power (nW or
uW) even when OFF or in
quiescent state. [7]

4. WHY MEMS SWITCHES ARE SUPERIOR THAT
WAY?
• For an ideal switch, requirements are:
• On resistance is zero
• Off resistance is infinite
• Off capacitance is zero

5. REAL MEMS SWITCHES
• In a real switch:
• On resistance is lower as it can have metal as a
conductor rather than semiconductor
• Off resistance is infinite due to air gap
• Capacitance still dominates the model and is to be
reduced by the designer.

6. FIGURE OF MERIT (FOM) FOR A SWITCH
• 𝐹𝑂𝑀 =
1
2π𝑅 𝑜𝑛 𝐶 𝑜𝑓𝑓
•For a higher FOM, the characteristics
should match that of an ideal switch, thus
FOM tends to infinity.

7. SWITCHING LOSSES
• 𝑃 =
1
2
𝐶𝑉2 𝑓2
• Higher the switching voltage and frequency, higher
the losses.
• Scaled for lowest power dissipation

8. THE OPERATING
REGION PROBLEM
As per the Bode plot for a
mechanical system, we have
3 regions:
• Below resonance
• At resonance (3dB
bandwidth)
• Above resonance

9. THE OPERATING REGIONS FOR MEMS
SWITCH
1. At resonance (resonating switch)
2. Below resonance

10. THE RESONATING SWITCH (RESOSWITCH)
• A cross-product of a resonator and a switch
• Operates in narrow 3db Bandwidth
• 𝑋 =
𝑄𝐹
𝑘

11. THE RESONATING SWITCH (RESO-SWITCH)
• Theoretically allows large gap sizes due to Q, thus small
parasitic losses.
• Phase of system is non-zero and varies sharply
• Large switching losses

12. WINE-GLASS RESO-SWITCH FOR AMPLIFIERS [2]

13. SWITCHING BELOW RESONANCE
• Operates in the flat region between DC and a decade before
resonant frequency
• 𝑋 =
𝐹
𝑘

14. SWITCHING BELOW RESONANCE
• Low switching losses
• Phase is ideally zero

15. DRIVING SWITCHES WITH HIGH PULL IN
VOLTAGE
• When pull in voltages are
high for a given design which
operates below resonance,
input voltage can be
amplified using:
• Charge pumps
• Gate drivers

16. SUSPENDED GATE RELAY FOR DIGITAL LOGIC
[1,3]

19. BAND SELECTOR SINGLE POLE 4 THROW RF
SWITCH [4]

20. RF MEMS SWITCH
• GE's tiny MEMS switch
measures just 100 microns
square and yet can switch up
to 5 kilowatts of power at 3
GHz.
(Source: General Electric) [5]

21. COMMERCIAL RF MEMS SWITCH BY OMRON [6]

22. RATINGS [6]

23. REFERENCES
1. Manohar et. al, “Heterogeneous NEMS-CMOS DCM Buck Regulator for Improved Area and Enhanced Power Efficiency”, IEEE
TRANSACTIONS ON NANOTECHNOLOGY, VOL. 14, NO. 1, JANUARY 2015
2. Nguyen et. al, “A resonance dynamical approach to faster, more reliable micromechanical switches,” Proceedings, 2008
IEEE Int. Frequency Control Symp., Honolulu, Hawaii, May 19-21, 2008, pp. 640-645
3. Hei Kam et. al, :Design and Reliability of a Micro-Relay Technology for Zero-Standby-Power Digital Logic Applications”,
4. Kang et. al, “Single Pole Four Throw Rf Mems Switch With Double Stop”, MEMS 2008, Tucson, AZ, USA, January 13-17,
2008
5. http://www.eetimes.com/document.asp?doc_id=1321677
6. http://www.mouser.com/ds/2/307/2SMES-01_0911-15621.pdf
7. Paul Gray Et Al, Analysis and Design of Analog Integrated Circuits, 5e