EB212

2

MOTOROLA SEMICONDUCTOR APPLICATION INFORMATION

SINGLE–ENDED DEVICES

The data sheet impedance format for single-ended devices

is illustrated in Figure 3. The impedance data is taken by

tuning the fixture for optimum* performance and then

measuring the impedance at the device reference plane.

Figure 4 shows the format for in-band frequency-depend -

ent impedances that should be presented to the device for

optimal performance. This measured data can be turned into

an S1P file as shown in Figure 5.

Note: The imaginary portion of the measured impedance

data has been conjugated from the data shown in Figure 4.

The impedances are to be conjugated from the data sheet

to account for rotation of reference frames. This means that

when data is first acquired, the measured data represents

impedances as seen by looking into the input side RF launch

point. However, the data needs to be presented as looking into

redirection of the arrows as well as the conjugation of the

measured impedance data.

*

An optimum tuned fixture will be tuned for overall peak performance considering all major parameters:

gate to ground.

= Test circuit impedance as measured

from drain to ground.

Z source

Z load

Input

Matching

Network

Device

Under Test

Output

Matching

Network

Figure 3. Data Sheet Impedance Format for

Single–Ended Devices

Figure 4. Optimal Impedances for an MRF19125

Test Fixture

f

MHz

Ω

Ω

1930

1960

1990

1.43 - j5.01

1.56 - j4.93

1.51 - j4.88

0.75 - j0.93

0.71 - j0.89

0.68 - j1.02

gate to ground.

= Test circuit impedance as measured

from drain to ground.

Z source

Z load

Input

Matching

Network

Device

Under Test

Output

Matching

Network

!

S11 (input) file

!

Circuit

: MRF19125

!

Author

: John Q. Designer

!

Date

: 01/01/2003

!

File

: mrf19125_zin.s1p

!

!

File Format:

#

MHz

Z

RE

IM

!

!

1930

1.43

5.01

1960

1.51

4.88

1990

1.56

4.93

!

!

End of File

Figure 5. S1P File of Impedances to Be Used

at Input Block

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com