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13

Pad Descriptions

Pad Number

Function

Description

Interface Schematic

1, 5, 8, 10,

13, 15, 20,

23, 25, 26,

Die Bottom

GND

These pads and the die bottom must be connected to a

high quality RF/DC ground.

2

EN

Enable pad. System is enabled when Ven is HIGH (VDIG).

If left floating, Ven defaults to HIGH (enabled).

3

SW

Internal switch resistance control pad. If left floating, VSW

defaults to HIGH.

12

DISBLSC

Disables short circuit lock down when pulled to ground.

Leave it floating to enable short circuit lock down.

4

VG2CONT

Control voltage of the VG2. Use a resistor divider between

VDD and GND to set the voltage. VG2 is typically 1.3V

lower than the VG2CONT

19

VG2

Second gate control.

6-7, 29-30

VDD, VDIG

Bias supply pan. Connect supply voltage

to this pad with appropriate filtering.

9

VREF

1.5V reference voltage. 0.1uF or greater capacitor to GND

is needed for noise filtering.

11

ISENSE

To adjust the bias current of the external amplifier connect

a resistor (Rsense) from ISENSE pad to GND. Use Eqn.2

to

determine the required Rsense value.

HMC981

v00.0611

ACTIVE BIAS CONTROLLER