1. 1
12/8/14
Group Members: Ryan Gough, Ashikur Rahman, Julian Cheng
Member Emeritus: Ehsan Yavari
SWITCHCRAFT
Project 1 Final Presentation
Group 2

2. 2
Project Objective
Design and build two solid state RF switches
One switch with PIN diode(s), and one with FET(s)
Primary Design Parameters
• Operational at 4 GHz
• Minimize insertion loss
• Maximize isolation
Secondary Design Parameters
• Minimize DC power consumption
• Simplicity
• Bandwidth

3. 3
The Gameplan
Parts Selection
VICTORY!
Acceptable
Performance?
Acceptable
Performance?
Modular Fab
(PIN)
Modular Fab
(FET)
Full Fab
(PIN)
Full Fab
(FET)
Acceptable
Performance?
Acceptable
Performance?
Initial Design
Rework/
Redesign
Rework/
Redesign
Rework/
Redesign
Rework/
Redesign
y y
y y
nn
nn

4. 4
Parts Selection
Chose PIN diode and FET based on low-cost, immediate availability,
advantageous operating parameters, and ease of modeling.
Manf. P/N
Max Fwd.
Current
Max ‘On’
Resis.
Max Total
Cap.
Inductance S2P?
Skyworks SMP1345-079LF 100 mA 2 Ω 0.20 pF 0.7 nH Yes
Manf. P/N Packaging
Max. Drain
Current
Pinch-off S2P? ADP model?
Avago ATF-38143 SOT-343 145 mA -0.5V Yes Yes

5. 5
PIN Diode Switch

6. 6
Initial Design – Diode Switch
Three shunt diodes with matching network
DIODE #1 DIODE #2 DIODE #3
DIODES OFF / SWITCH ON: Low-value capacitor presents high
impedance to primary line
DIODES ON / SWITCH OFF: Primary line exposed to quarter-wave
transformer stub; creates three short circuit nodes 90° apart

7. 7
Initial Design – Diode Switch
Device parasitics
already included in S2P
Stub is performing tuning;
extra cap not needed

8. 8
Diode Switch - Modular Fabrication
Iteration #1: Tuning stub worked, but inductor position at the
lower end limited available tuning range.

9. 9
Diode Switch - Modular Results
Single-stage shunt diode with open-circuit tuning stub

10. 10
Diode Switch
Stubs create RF short circuit at three points (90° apart) to
discourage anti-nodes

11. 11
Diode Switch Results
Isolation: 57.6 dB (@ 4.07 GHz)
Better than 20 dB: 3.54 – 4.47 GHz (23.3%)
VDC = 1.8 VDC
IDC = 300 mA

12. 12
Diode Switch Results
Insertion Loss: 1.3 dB
3dB Bandwidth: 1.84 GHz (46%)
VDC = -2 VDC
IDC = 0 mA

13. 13
FET Switch

14. 14
Initial Design – FET Switch
Two FETs in series; gate-controlled

15. 15
Initial Design – FET Switch
Insertion Loss: 0.3 dB
Isolation: 19.4 dB
This switch stuff is easy!!!!
+3VDC Vgs -3VDC Vgs

16. 16
FET Switch Trouble
Series FET deviates significantly from ADS simulation
Measured data courtesy Group 3
~7.2 dB disparity
in isolation

17. 17
FET Switch Updated Design
Simplified design and switched (!) to shunt topology

18. 18
Insertion Loss: 2.3 dB
Isolation: 40.2 dB
FET Simulated Results

19. 19
FET Switch
FET
Tuning
stub

20. 20
FET Switch Results
Isolation: 22.3 dB (@ 4.0 GHz)
Better than 20 dB: 3.63 – 4.15 GHz (13%)
VDC = -0.9 VDC
IDC = < 1 mA

21. 21
FET Switch Results
Insertion Loss: 6.2 dB (@ 4.0 GHz)
VDC = 0 VDC
IDC = 0 mA

22. 22
FET Switch Results
Best case insertion loss: 3.1 dB (@ 4.0 GHz)
At this stub length, isolation is only 7.0 dB

23. 23
FET Switch Results
Isolation improves as a function of stub length on either side of 4 GHz. : (

24. 24
Summary
Successfully fabricated RF switches with both PIN diodes
and FETs.
PIN Diode Switch
• Num. Devices: 3
• DC Power: 540 mW (1.8 VDC @ 300 mA)
• Insertion Loss: 1.3 dB
• Isolation: 57.6 dB
FET Switch
• Num. Devices: 1
• DC Power: < 1 mW (0.9 VDC @ < 1 mA)
• Insertion Loss: 6.2 dB (3.1 dB best case)
• Isolation: 22.3 dB

25. Supplemental

26. 26
Parts Selection – PIN Diodes
Need a low-cost, readily available option that operates @ 4 GHz
Manf. P/N Packaging In Stock?
Cost
(per unit)
Dist.
Upper
Freq.
Infineon BAR 64-03W E6327 SOD 323 Yes
$0.50
($0.297 @
10)
Mouse
r
“SHF”
Infineon BAR 64-02V H6327 SC 79 Yes
$0.51
($0.359 @
10)
Digikey 6 GHz
MACOM
MADP-0110280-
1415OT
SMD Yes
$3.05
($2.47 @ 10)
Mouse
r
12
GHz
MCC BAP51-02-TP SOD-523 Yes
$0.52
($0.371 @
10)
Digikey N/A
Skyworks SMP1345-079LF SC 79 Yes
$0.55
($0.503 @
10)
Mouse
r
6 GHz

27. 27
Parts Selection – PIN Diodes
Performance specs? Ease of simulation?
Manf. P/N
Max Fwd.
Current
Max ‘On’
Resis.
Max Total
Cap.
Induct
ance
S2P?
Infineon BAR 64-02V H6327 100 mA 1.35 Ω 0.17 pF 0.6 nH No
Skyworks SMP1345-079LF 100 mA 2 Ω 0.20 pF 0.7 nH Yes
Infineon has slightly better specs at a slightly lower price, but without an S2P file
it will be more difficult to model.
Final decision was to select the Skyworks SMP1345.

28. 28
MESFETs expensive… expanded search to include other FETs.
Manf. P/N Packaging In Stock?
Cost
(per unit)
Upper
Freq.
FET Type
MWT MWT-773 Pkg 73 Yes $27.40 26 GHz MESFET
Avago ATF-58143 SOT-343 Yes $2.87 6 GHZ pHEMT
CEL
NE3510M04-
A
M04 Yes $1.75 12 GHZ HJFET
Avago ATF-33143 SOT-343 Yes
$4.10
($3.65 @ 10)
10 GHZ pHEMT
Avago ATF-38143 SOT-343 Yes $1.31 10 GHZ pHEMT
Parts Selection – FETs

29. 29
Other parameters?
Manf. P/N Packaging
Max.
Drain
Current
Pinch-off S2P?
ADP
model?
CEL
NE3510M04-
A
M04 97 mA -0.7V No No
Avago ATF-38143 SOT-343 145 mA -0.5V Yes Yes
The Avago FET is less expensive, and comes with both S2P files and an ADP model.
Parts Selection – FETs

30. 30
Device Operation
PIN Diode
• Wide intrinsic region acts as low-value
capacitor under reverse bias
• Variable RF resistor under forward bias
Field Effect Transistor
• Gate voltage below pinch-off prevents
current through channel; drain-source
capacitance remains
• Gate voltage above pinch-off allows
conduction; variable resistor to RF
Images from Agilent white paper: “Understanding RF/Microwave Solid State
Switches and their Applications”

32. 32
Diode Switch - Modular Fabrication
Iteration #2: Moved inductor to top of stub… success!
(Re-purposed SMAs before remembering to take a photo. Whoops.)

33. SC-79

34. 34
Initial Design – FET Switch
Open circuit stub for matching

35. M04

36. SOT-343