Data Sheet

ADPA7005CHIP

Rev. 0 | Page 17 of 23

BIASING ADPA7005CHIP WITH THE HMC980LP4E

The HMC980LP4E is an active bias controller that is designed

to meet the bias requirements for enhancement mode and

depletion mode amplifiers such as the ADPA7005CHIP. The

controller provides constant drain current biasing over temperature

and part to part variation, and properly sequences gate and

drain voltages to ensure the safe operation of the amplifier. The

HMC980LP4E also offers self protection in the event of a short

circuit, as well as an internal charge pump that generates the

negative voltage needed on the gate of the ADPA7005CHIP,

and the option to use an external negative voltage source.

HMC980LP4E is also available in die form as the HMC980-DIE.

Figure 54. Functional Diagram of HMC980LP4E

APPLICATION CIRCUIT SETUP

Figure 55 displays the schematic of an application circuit using

the HMC980LP4E to control the ADPA7005CHIP. When using

an external negative supply for VNEG, refer to the schematic in

Figure 56.

In the application circuit shown in Figure 55, the ADPA7005CHIP

drain voltage and drain current are set by the following equations:

(2)

MAXIMUM RATING REQUIREMENT

When using the HMC980LP4E to control the ADPA7005CHIP,

the minimum voltages for VNEG and VGATE must be −1.5 V

to keep these voltages within the absolute maximum rating

minimum voltages, set R15 and R16 to the values shown in

Figure 55 and Figure 56. Please refer to the AN-1363 for more

information and calculations for R15 and R16.

2

1

3

4

5

6

18

17

16

15

14

13

ALM

EN

S1

S0

VDD

VDD

VG2_CONT

PACKAGE

BASE

GND

VG2

VNEG

VGATE

VDRAIN

VDRAIN

CONTROL

BLOCK

GATE

CONTROL

BAND GAP

NEGATIVE

VOLTAGE

GENERATOR