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

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December 2006

VG112

PCS/UMTS-band Variable Gain Amplifier

2140 MHz Application Circuit Performance

Performance using the circuitry on the VG112-PCB Evaluation Board

• The center of C5 should be placed 5mm (.197”) away from the edge of the VG112.

• The input trace is a high impedance line and is needed to get a good input match into the VGA.

• The board is optimized for performance at 2140 MHz.

Performance at 1960 MHz can be

optimized by replacing C5 with 2.7 pF at location A on the WJ VG112 evaluation board.

Circuit Board Material: .014” FR-4, 4 layers, .062” total thickness

Bill of Materials

Ref. Des.

Description

Size

C1, C7, C10 47 pF Chip Capacitor

0603

C2, C3, C4,

C8, C9

1000 pF Chip Capacitor

0603

C5

2.4 pF Chip Capacitor

0603

C6

3.3 µF Chip Capacitor

0805

L1, L2

18 nH Chip Inductor

0603

R1

220 Ω Chip Resistor

0603

R3

75 Ω Chip Resistor

0603

R2, R4

0 Ω Chip Resistor

0603

U1

VG112-G VGA

QFN 6x6

S21 vs. Frequency

Vctrl=0V (Maximum Gain Setting)

18

20

22

24

26

28

1800

1900

2000

2100

2200

Frequency (MHz)

-40 °C

+25 °C

+85 °C

S11 vs. Frequency

Vctrl=0V (Maximum Gain Setting)

-25

-20

-15

-10

-5

0

1800

1900

2000

2100

2200

Frequency (MHz)

-40 °C

+25 °C

+85 °C

S22 vs. Frequency

Vctrl=0V (Maximum Gain Setting)

-25

-20

-15

-10

-5

0

1800

1900

2000

2100

2200

Frequency (MHz)

-40 °C

+25 °C

+85 °C

S21 vs. Frequency vs. Control Voltage

-10

0

10

20

30

1800

1900

2000

2100

2200

Frequency (MHz)

Vctrl=0.00V

Vctrl=0.73V

Vctrl=1.06V

Vctrl=1.52V

Vctrl=2.20V

Vctrl=4.50V

S11 vs. Frequency vs. Control Voltage

-25

-20

-15

-10

-5

0

1800

1900

2000

2100

2200

Frequency (MHz)

Vctrl=0.00V

Vctrl=0.73V

Vctrl=1.06V

Vctrl=1.52V

Vctrl=2.20V

Vctrl=4.50V

S22 vs. Frequency vs. Control Voltage

-25

-20

-15

-10

-5

0

1800

1900

2000

2100

2200

Frequency (MHz)

Vctrl=0.00V

Vctrl=0.73V

Vctrl=1.06V

Vctrl=1.52V

Vctrl=2.20V

Vctrl=4.50V