Specifications and information are subject to change without notice

WJ Communications, Inc • Phone 1-800-WJ1-4401 • FAX: 408-577-6621 • e-mail: sales@wj.com • Web site: www.wj.com

Page 10 of 12 October 2006

FP31QF

2-Watt HFET

Product Information

The Communications Edge

TM

Reference Design: 3500 MHz

The application circuit is matched for output power.

Typical RF Performance

Frequency

MHz

3500

S21 – Gain

dB

11.9

S11 – Input Return Loss

dB

-16

S22 – Output Return Loss

dB

-8.8

Output P1dB

dBm

+33.5

Output IP3

(+18 dBm / tone, 1 MHz spacing)

dBm

+45

The 3.5 GHz Reference Circuit is shown for design purposes only. An

evaluation board is not readily available for this application. The reader can

obtain any FP31QF evaluation board and modify it with the circuit shown to

achieve the performance shown in this reference design.

3.3

3.35

3.4

3.45

3.5

3.55

3.6

3.65

3.7

Frequency (GHz)

Measured S-Parameters

-25

-20

-15

-10

-5

0

5

10

15

DB(|S[1,1]|)

DB(|S[2,1]|)

DB(|S[2,2]|)

4 layers (other layers added for rigidity), .062” total thickness, 1 oz copper

The main microstrip line has a line impedance of 50

.

Bill of Materials

Ref. Desig.

Value

Part style

Size

C1, C4, C8, C10

22 pF

Chip capacitor

0603

C2

0.9 pF

Chip capacitor

0603

C3

1.0 pF

Chip capacitor

0603

C7, C11

1000 pF

Chip capacitor

0603

C12

0.1 µF

Chip capacitor

1206

L1, L2

6.8 nH

Wirewound chip inductor

0805

L3

3.3 nH

Multilayer chip inductor

0603

R1

2.2

Chip resistor

0603

R2

50

Chip resistor

0603

Q1

FP31QF

WJ 2W HFET

QFN 6x6

C5, C6

Do Not Place

• Both the C2 and C3 placements are between the first and second via locations

along the main microstrip line leading from the FP31QF device. Further

descriptions are shown in the diagram on the left.

• The via hole spacing along the main microstrip line is .040”.

• The distance from the edge of the FP31QF to the closer edge of L3 is .305”.

• The transmission line lengths shown in the schematic are from the FP31QF

device edge to the component edge.

ID=C1

C=22 pF

ID=C2

C=0.9 pF

ID=C3

C=1 pF

ID=C4

C=22 pF

ID=C8

C=22 pF

ID=C7

C=1000 pF

ID=C10

C=22 pF

ID=C12

C=1e4 pF

ID=C11

C=1000 pF

ID=L1

L=6.8 nH

ID=L2

L=6.8 nH

ID=L3

L=3.3 nH

ID=R1

R=2.2 Ohm

ID=R2

R=51 Ohm

TLIN

Z0=50 Ohm

EL=55 Deg

F0=3.5 GHz

TLIN

Z0=50 Ohm

EL=5.9 Deg

F0=3.5 GHz

TLIN

Z0=50 Ohm

EL=12.8 Deg

F0=3.5 GHz

1

2

NET="FP31QF"

-Vgg

Vds=9V @ 450 mA

C2

C3