MRF1550NT1_08 Datasheet, PDF (10/18 Pages) Freescale Semiconductor, Inc – RF Power Field Effect Transistors

AMPLIFIER DESIGN
Impedance matching networks similar to those used with
bipolar transistors are suitable for this device. For examples
see Freescale Application Note AN721, “Impedance
Matching Networks Applied to RF Power Transistors.”
Large - signal impedances are provided, and will yield a good
first pass approximation.
Since RF power MOSFETs are triode devices, they are not
unilateral. This coupled with the very high gain of this device
yields a device capable of self oscillation. Stability may be
achieved by techniques such as drain loading, input shunt
resistive loading, or output to input feedback. The RF test fix-
ture implements a parallel resistor and capacitor in series
with the gate, and has a load line selected for a higher effi-
ciency, lower gain, and more stable operating region.
Two - port stability analysis with this device’s
S - parameters provides a useful tool for selection of loading
or feedback circuitry to assure stable operation. See Free-
scale Application Note AN215A, “RF Small - Signal Design
Using Two - Port Parameters” for a discussion of two port
network theory and stability.
MRF1550NT1 MRF1550FNT1
10
RF Device Data
Freescale Semiconductor