Electrical Characterization of Packages for Use with GaAs

MMIC Amplifiers

Rev. V4

Application Note

M542

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3

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Experimental Results

The feedthrough walls of each package listed in

Table 1 have been tested and modeled.

This

feedthrough data alone largely indicates the useful

frequency range of each package. Figure 5 shows

the frequency response for the feedthrough of the

8-lead ceramic flatpack. This package, previously

thought to be useful only at lower frequencies,

demonstrates excellent performance well into X-

band before resonating. Based on this result, we

assembled our 2-8 GHz GaAs MMIC amplifier into

this package. The performance of this packaged

amplifier, part number MAAM28000-A1, is shown

in Figure 6.

Figure 5. Feedthrough Frequency

Response

Figure 6. MAAM28000-A1 Performance

Using the de-embedded feedthrough data, Y-

parameter extraction followed by a constrained op-

timization was performed to derive the feedthrough

model shown in Figure 7.

Figure 8 shows the measured versus modeled in-

sertion loss and input return loss for this package

feedthrough. The model simulates the feedthrough

performance closely over the useful frequency

range of the package.

Figure 7. Feedthrough Model

Figure 8. Measured vs. Modeled

Performance

Coupling effects between package ports were also

measured and modeled. A Y-parameter extraction

showed that the coupling could be attributed to

equivalent capacitance values. In the case of the

8-lead ceramic flatpack, coupling between adjacent

ports along one side of the flatpack can be repre-

sented by a 0.03 pF capacitance. Between alter-

nate ports along the same side, the coupling ca-

pacitance is nominally 0.003 pF.

Coupling be-

tween internally terminated ports on opposite sides

of the flatpack was modeled with a 0.0007 pF ca-

pacitor.

This coupling model accurately predicts

the measured input to output isolation, as illus-

trated in Figure 9, over the package’s useful fre-

quency range.

-20

-15

-10

-5

0

5

10

15

20

0246

8

10

Gain

S11

S22

Frequency (GHz)