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Data Sheet

ADPA7009-2

BIASING THE ADPA7009-2 WITH THE HMC980LP4E

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After the HMC980LP4E bias control circuit is set up, toggle the bias

to the ADPA7009-2 on or off by applying 3.3 V or 0 V, respectively,

to the EN pin. At EN = +3.3 V, VGATE drops to −1.5 V, and

VDRAIN turns on at +5 V. VGATE then rises until IDRAIN = 950 mA,

and the closed control loop regulates IDRAIN at 950 mA. When EN =

0 V, VGATE is set to −1.5 V, and VDRAIN is set to 0 V.

CONSTANT DRAIN CURRENT BIASING VS.

CONSTANT GATE VOLTAGE BIASING

The HMC980LP4E uses closed-loop feedback to continuously ad-

just VGATE to maintain a constant drain current bias over DC

supply variation, temperature, and device-to-device variation. In

addition, constant drain current bias is the optimum method for re-

ducing time in calibration procedures and for maintaining consistent

performance over time. Comparing the constant drain current bias

with a constant gate voltage bias where the current is driven to

increase when RF power is applied, a slightly lower OP1dB is seen

with a constant drain current bias. This OP1dB is shown in Figure

78, where the RF performance is slightly lower than the constant

gate voltage bias operation due to a lower drain current at the high

input powers as the device reaches 1 dB compression.

To increase the OP1dB performance for the constant drain current

bias toward the constant gate voltage bias performance, increase

the setpoint current, bringing it closer to the maximum IDD current,

as shown in Figure 78. The limit of increasing IDQ under the

constant drain current operation is set by the thermal limitations

found in Table 4 with the maximum power-dissipation specification.

As the IDD increase continues, the actual OP1dB does not continue

to increase indefinitely, and the power dissipation increases. There-

fore, when using constant drain current biasing, take the trade-off

between the power dissipation and the output P1dB performance

into consideration.

CONSTANT IDD OPERATION

TCASE = 25°C, VDD = 5 V, and IDD = 950 mA for nominal operation,

unless otherwise noted. Figure 71 to Figure 78 are biased with

the HMC980LP4E active bias controller. See the Biasing the AD-

PA7009-2 with the HMC980LP4E section for biasing details.

Figure 71. OP1dB vs. Frequency for Various Temperatures, VDD = 5 V, Data

Measured with Constant IDD = 950 mA

Figure 72. OP1dB vs. Frequency for Various IDQ Values, VDD = 5 V, Data

Measured with Constant IDD = 950 mA

Figure 73. IDD vs. PIN, VDD = 5 V, Frequency = 36 GHz, Constant Drain Current

(IDRAIN Setpoint = 950 mA) and Constant Gate Voltage (IDQ = 850 mA)

ADPA7009-2ACEZ-R7 Datasheet(PDF) 22 Page - Analog Devices

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