ADPA7006CHIP datasheet(18/24 Pages) AD

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ADPA7006CHIP

Data Sheet

Rev. 0 | Page 18 of 24

BIASING THE ADPA7006CHIP WITH THE HMC980LP4E

The HMC980LP4E is an active bias controller designed to meet

the bias requirements for enhancement mode and depletion

mode amplifiers, such as the ADPA7006CHIP. The controller

provides constant drain current biasing over temperature and

device to device 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, an internal charge pump that generates the negative

voltage needed on the gate of the ADPA7006CHIP, and

the option to use an external negative voltage source. The

HMC980LP4E is also available in die form as the HMC980-

DIE.

ALM

VDD

VG2_CONT

PACKAGE

BASE

GND

VG2

VNEG

VGATE

VDRAIN

CONTROL

BLOCK

GATE

CONTROL

HMC980LP4E

BAND GAP

NEGATIVE

VOLTAGE

GENERATOR

Figure 54. HMC980LP4E Active Bias Control

APPLICATION CIRCUIT SETUP

Figure 55 shows an application circuit using the HMC980LP4E

to control the ADPA7006CHIP. When using an external negative

supply for VNEG, refer to the application circuit shown in

Figure 56.

In the application circuit shown in Figure 55, the ADPA7006CHIP

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

VDRAIN (5 V) = VDD (5.77 V) − IDRAIN (900 mA) × 0.85

IDRAIN (900 mA) = 150 ÷ R10 (125 Ω)

LIMITING VGATE FOR THE ADPA7006CHIP VGGx

AMR (ABSOLUTE MAXIMUM RATING)

REQUIREMENT

When using the HMC980LP4E to control the ADPA7006CHIP,

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

to keep them within the absolute maximum rating limit for the

VGGx pad of the ADPA7006CHIP. To set the minimum voltages, set

R15 and R16 to the values shown in Figure 56 and Figure 57. Refer

to the AN-1363 Application Note for more information and

calculations for R15 and R16.

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