Data Sheet

ADPA1113

APPLICATIONS INFORMATION

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Rev. 0 | 16 of 17

APPLICATIONS CIRCUIT

Figure 46. Typical Application Circuit

BASIC CONNECTIONS

The basic connections to operate the ADPA1113 are shown in

Figure 46.The same drain supply voltage, 28 V nominal, must be

applied to all of the five VDD pins (VDD1, VDD2A, VDD2B, VDD3A,

and VDD3B). The VDD pins are capactively decoupled as shown

in Figure 46. The gate voltage for all three stages (−1.9 V to −4.0

V for biased operation and −8 V for pinch-off voltage) is applied to

the VGG1 pin that is decoupled as shown in Figure 46. Pin 1 and

Pin 7 are designated as no internal connection (NIC) pins. Although

these NIC pins are not internally connected, the NIC pins were all

connected to ground during the characterization of the device.

To turn on the device, apply −4 V to VGG1 which places it in

pinch-off voltage. Then, apply 28 V to VDD1, VDD2A, VDD2B,

VDD3A, and VDD3B. Increase the gate voltage (more positive) until

the drain current is 750 mA, VGG1 is approximately −2 V, and apply

the RF signal. If the desired gate voltage is known in advance,

VGG1 can be set to that voltage directly without going through the

pinch-off step.

To turn off the device, turn off the RF signal and set the VDD

voltages to 0 V before increasing VGG1 to 0 V.

The configuration shown in Figure 46, which is also the default

configuration of the customer evaluation board, was used to char-

acterize the ADPA1113. It can be possible to reduce the number

of power supply decoupling capacitors shown, but this reduction

varies by system. When reducing capacitors, the recommendation

is to first remove or combine the largest capacitors that are farthest

from the device.

Soldering and Assembly Considerations

The ADPA1113 is a nonhermetic air cavity device. The body of the

package normally sits within a cutout in the PCB that allows direct

access to a heatsink beneath the PCB. To facilitate good thermal

and electrical conduction to the heatsink, a shim of electrically

and thermally conductive material such as Heat-Spring indium from

Indium Corporation can be used. (Alternatively, electrically and

thermally conductive paste or grease can be used). The shim is

placed between the heatsink and the bottom of the package flange.

Then, the package can be attached to the heatsink using 0-80

thread size, 3/16 inches long stainless steel socket head screws

(typically). Once attached with the screw hardware, the pins are

flush with the PCB which allows the leads to be soldered to the

PCB pads.