Data Sheet P11491EJ4V0DS00

5

TEST CIRCUIT

1 800 pF

1 800 pF

1 800 pF

L

5

1

8

2, 3, 4, 6, 7

OUT

IN

50

Ω

50

Ω

L: 20.5 T, 2 mm I.D.,

0.25 UEW

(about 300 nH)

φ

INDUCTOR FOR THE OUTPUT PIN

The internal output transistor of this IC consumes 30 mA, to output medium power. To supply current for output

The inductor has both DC and AC effects. In terms of DC, the inductor biases the output transistor with minimum

voltage drop to output enable high level. In terms of AC, the inductor make output-port impedance higher to get

enough gain. In this case, large inductance and Q is suitable.

for the input and output pins.

The coupling capacitors, connected to the input and output pins, are used to cut the DC and minimize RF serial

impedance. Their capacitance are therefore selected as lower impedance against a 50

Ω load. The capacitors thus

perform as high pass filters, suppressing low frequencies to DC.

To obtain a flat gain from 100 MHz upwards, 1 800 pF capacitors are used in the test circuit. In the case of under

100 MHz operation, increase the value of coupling capacitor such as 10 000 pF. Because the coupling capacitors

are determined by equation, C = 1/(2

πRfc).