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Figure 7.33:
Output characteristics of a
= 300 nm AlGaAs/InGaAs HEMT on GaAs substrate.
|
Technology D is designed primarily to match high-power requirements in X-band (8-12 GHz)
to the Ka-band (26.5- 40 GHz).
Figure 7.34:
Measured temperature dependence
of
and
for
= 300-473 K for a
= 150 nm device.
|
Fig. 7.33 shows the simulated and measured
output characteristics of a pseudomorphic AlGaAs/ InGaAs/ GaAs
HEMT with
= 300 nm.
Scaling the device to
= 150 nm allows for high-power applications up to 42 GHz.
Fig. 7.34 shows the simulated and measured transconductance
and
at
= 5 V
for a HEMT with
= 150 nm for the temperature range between
= 300 K and
= 473 K.
Considering an operational voltage of typically
=
5 V for a high-power device, the limitation of a double recess
concept can be seen in Fig. 7.34. Although this device
provides extremely high output power levels up to 42 GHz, as shown
in Chapter 6, for applications beyond 42 GHz aggressive gate
length scaling to
= 100 nm [131] is necessary to
reduce capacitances. An alternative is the use of single recess
devices, such as Technology C, at reduced
voltage to ensure
reliability. A possible alternative under consideration is the
metamorphic materials system with well chosen In content, as
discussed below, to overcome the gain shortage for f
42 GHz
and to achieve better PAE.
Next: 7.6 Technologies Based on
Up: 7. Simulation Studies
Previous: 7.4 Technology C: Pseudomorphic HEMT
Quay
2001-12-21