Transcript No Slide Title

Project Introduction and Motivation
Started 1 May 99
October 1999
•Millimeter-wave switches may be used in a variety of applications, including
Millimeter-wave imaging system and collision avoidance systems.
Millimeter-wave power control systems.
Moderate pulse radar reflectometry for plasma diagnostics.
.
• Beam control array technology offers the possibility of achieving high speed and
high power handling capability with increased dynamic range.
• Silicon based microelectromechanical system (MEMS) switches have the potential
to form low cost, high performance, ultrawide quasi-optical control elements for
advanced defense and commercial applications.
MVE MURI 99 Kick-off Meeting
R. Barker, Technical Monitor
High Speed Switching System Design
Started 1 May 99
October 1999
Switch Array
Switched Mmwave Output
CW Mmwave Input
E
Matching Plate
Matching Plate
Bias
Microstrip Wilkison Power Divider
Microstrip to CPW Transition
Wirebond from Bias Board to
GaAs Wafer
The high speed switch consists of a quasi-optical beam control array, matching system, and high speed
bias circuitry.
Quasi-optical power combining techniques are utilized to obtain high output power by combining the
power of thousands of diodes.
The control speed is limited by three factors: the quasi-optical array physical dimensions, bias circuitry,
and diode grid layout.
MVE MURI 99 Kick-off Meeting
R. Barker, Technical Monitor
Introduction to High Speed Quasi-Optical
Arrays
Started 1 May 99
October 1999
MVE MURI 99 Kick-off Meeting
R. Barker, Technical Monitor
Equivalent Circuit Model of the Diode
Grid Unit Cell
Started 1 May 99
October 1999
Ld
Cgrid
Varactor
Diode
Rs
Cp
Equivalent Circuit for Diode Grid Unit Cell
SEM photo of Unit cell
E-Field Distribution of Top View of Schottky Varactor
MVE MURI 99 Kick-off Meeting
R. Barker, Technical Monitor
High Speed Switch Array with Bias
Control Board
Started 1 May 99
MVE MURI 99 Kick-off Meeting
R. Barker, Technical Monitor
October 1999
High Speed Beam Control Switch
Testing Setup
Started 1 May 99
V-K Trans.
BWO
October 1999
K-V Trans
Atten. Directional
Coupler
Power
Detector
Frequency
Meter
Overmode
Waveguide
Mounting Fixture
Isolator Diode
Detector
Sampling Oscilloscope
Signal Generator
Pulse Circuit
Trigger
MVE MURI 99 Kick-off Meeting
R. Barker, Technical Monitor
Signal
High Speed Switch Testing Results
Started 1 May 99
October 1999
20
Contrast Ratio (dB)
15
10
Measured
Simulated
5
0
54
56
58
60
62
64
66
Frequency (GHz)
Comparison Between Measured and Simulated Contrast Ratio

<1.5 dB insertion loss and 16.8 dB on/off contrast ratio measured at 60 GHz.The switch fall
time is <127 psec, rise time is 168 psec with pulse width (FWHM) 317 psec limited by bias pulse.

> 10 dB on/off contrast ratio for the frequency band from 55 GHz to 66 GHz.The measured
results are very close to the simulation results.
MVE MURI 99 Kick-off Meeting
R. Barker, Technical Monitor
New High Speed Switch Performance
Started 1 May 99

October 1999
High speed, monolithic millimeter wave switch arrays, which will operate at V-
band and W-band, have been designed and are being fabricated

In the new class high speed switch system, a new 1:8 wilkinson power divider
and a new optimized overmoded K-band mounting fixture will be used.

The grid switch array size is 0.4 x 1 cm2. There are around 400 Schottky varactor
diodes on the wafer, and it can handle power levels in excess of 1 W.

Lower insertion loss and higher contrast ratio is expected:
V-band switch array: < 1 dB insertion loss and 27 dB ON/OFF contrast ratio.
W-band switch array: < 2.5 dB insertion loss and > 25 dB ON/OFF contrast ratio.
MVE MURI 99 Kick-off Meeting
R. Barker, Technical Monitor
Introduction: Microelectromechanical
System (MEMS)
Started 1 May 99
October 1999
•MEMS stands for Micro-Electro-Mechanical System, where the physical dimensions
are on the order of a few or tens of microns.
•There are two advantage of RF MEMS devices compared to traditional semiconductor
devices:
a. Electromechanical isolation
b. Power consumption
• Developments in MEMS technologies have facilitated exciting advancements in the
fields of sensors (accelerometers and pressure sensors), micromachines (microsized
pumps and motors), and control components (high definition TV displays and spatial
light modulators).
MVE MURI 99 Kick-off Meeting
R. Barker, Technical Monitor
Microwave / Millimeter Wave MEMS
Switch Operation
Started 1 May 99
4 m Metal
October 1999
0.3 m Al
Membrane
V+
V-
Silicon Wafer
0.3 m Al
The MEMS switch consists of two metal plates, a fixed base plate and a movable thin film membrane.
Electrically, the MEMS switch is a nonlinear function of the DC bias applied to the switch.
Through the application of a DC electrostatic field, the MEMS membrane is attracted towards a metalized
bottom contact.
MVE MURI 99 Kick-off Meeting
R. Barker, Technical Monitor
SEM Photo of MEMS Switch
Started 1 May 99
October 1999
•The top metal with holes is a movable membrane, which is supported by Al post.
•The holes are employed to etch the sacrificial layer using a plasma etcher. The unit
cell size is 1200 x1200 µm2, and membrane is 120 x120 µm2.
MVE MURI 99 Kick-off Meeting
R. Barker, Technical Monitor
MEMS Switch Array Layout
Started 1 May 99
MVE MURI 99 Kick-off Meeting
October 1999
R. Barker, Technical Monitor
Started 1 May 99
MDS Simulation of MEMS Power
Control Array
-15
-0.4
-20
-0.6
-25
Cm ax (Off)
-30
-0.8
-35
-40
-1
50
55
60
65
Frequency (GHz)
70
0
Cm a x (O ff)
Reflection Loss in Off Mode (dB)
-0.2
-10
Insertion Loss in On Mode (dB)
Cm in (On)
-5
Insertion Loss in Off Mode (dB)
0
0
-5
-0. 1
-10
-0. 2
-15
-20
-0. 3
Cm in ( On)
-25
-0. 4
-30
-0. 5
-35
50
55
60
65
Frequency (GHz)
70
The MDS simulation tool has been used to simulate the MEMS switch array.
The contrast ratio is > 20 dB over a 20 GHz bandwidth.
MVE MURI 99 Kick-off Meeting
Reflection Loss in On Mode (dB)
0
October 1999
R. Barker, Technical Monitor
Design of MEMS Tunable Filters
Started 1 May 99
October 1999
LC
Circuit
QO MEMS Tunable Filter System
Transmission
Line
LC
Circuit
Transmission
Line
Equivalent circuit of the Tunable Filter
MEMS Tunable QO filter consists of sevearl pieces, an LC resonant circuit is fabricated on
each of the wafer surfaces.
MVE MURI 99 Kick-off Meeting
R. Barker, Technical Monitor
Simulation Result of W-band Tunable
Filter
Started 1 May 99
October 1999
Pass- Band o f Tunable Filter
0
Phase of W-band Tunable filte r
-2
S 2 1 (d B)
100
Tune 1
Tune 2
50
Tune 1
Tune 2
-4
-6
-8
-10
90
95
100
Frequency(GHz)
105
110
40
45
0
Sto p-B an d of Tun able Filter
0
-50
Tune 1
Tune 2
S 2 1 (d B)
-5
-100
25
30
35
40
45
-10
-15
-20
25
30
35
W-band tunable filter can tune ~30 degree phase shift From 30GHz---40GHz.
MVE MURI 99 Kick-off Meeting
R. Barker, Technical Monitor
Ongoing Activities
Started 1 May 99
October 1999
•A new class of GaAs based V-band and W-band high speed monolithic millimeter
wave switch array has been designed and is being fabricated.
•MEMS Switch array technology is being developing. MEMS based quasi-optical
arrays will be employed as quasi-optical power control, quasi-optical phase shifters,
and tunable quasi-optical filters.
MVE MURI 99 Kick-off Meeting
R. Barker, Technical Monitor