![[LDMOS Device]](./images/dope.gif)
LDMOS Device Analysis
This page contains some plots that show the operation of an LDMOS
RF power amplifier under large signal sinusoidal perturbation. The
LDMOS device is shown on this page with a contour plot of the
dopant concentration around the channel region. The color scale
corresponds to the log base 10 of the doping where negative
implies P-type
dopant. For more information on this device
structure, the circuit in which
it is placed, and
the running of the simulations
described on this pages, please refer to this
paper
from the SISPAD '97 conference. Only the results are shown here.
The large signal simulation of this device involves finding
the gain and efficiency as describe in the SISPAD paper. From
the plots of the gain and efficiency, six points are chosen in
order to examine the device in closer detail. These points are
shown on each plot for the
gain versus pout,
efficiency versus pout,
and
pout versus pin.
In the time domain, the voltages and currents at the terminals
are given in the following plots. In each plot, the six curves
represent the six points of interest.
- Vdrain
- Idrain
- Vgate
- Igate
In addition, each of these time domain plots may be
examined in the frequency domain. Note that the
3rd order and 5th order harmonics tend to increase much
more that the 2nd and 4th order harmonics.
- Spectrum for Drain Voltage
- Point 1: Pin=12.4dbm / Pout=26.0dbm
- Point 2: Pin=17.5dbm / Pout=30.0dbm
- Point 3: Pin=20.7dbm / Pout=31.7dbm
- Point 4: Pin=23.3dbm / Pout=32.5dbm
- Point 5: Pin=26.9dbm / Pout=33.2dbm
- Point 6: Pin=29.3dbm / Pout=33.6dbm
- Spectrum for Gate Voltage
- Point 1: Pin=12.4dbm / Pout=26.0dbm
- Point 2: Pin=17.5dbm / Pout=30.0dbm
- Point 3: Pin=20.7dbm / Pout=31.7dbm
- Point 4: Pin=23.3dbm / Pout=32.5dbm
- Point 5: Pin=26.9dbm / Pout=33.2dbm
- Point 6: Pin=29.3dbm / Pout=33.6dbm
- Spectrum for Drain Current
- Point 1: Pin=12.4dbm / Pout=26.0dbm
- Point 2: Pin=17.5dbm / Pout=30.0dbm
- Point 3: Pin=20.7dbm / Pout=31.7dbm
- Point 4: Pin=23.3dbm / Pout=32.5dbm
- Point 5: Pin=26.9dbm / Pout=33.2dbm
- Point 6: Pin=29.3dbm / Pout=33.6dbm
- Spectrum for Gate Current
- Point 1: Pin=12.4dbm / Pout=26.0dbm
- Point 2: Pin=17.5dbm / Pout=30.0dbm
- Point 3: Pin=20.7dbm / Pout=31.7dbm
- Point 4: Pin=23.3dbm / Pout=32.5dbm
- Point 5: Pin=26.9dbm / Pout=33.2dbm
- Point 6: Pin=29.3dbm / Pout=33.6dbm
Inside the device, the following plots of electron concentration,
hole concentration, electric fields, and potentials provide even
more insight into the performance of the device. Note especially
the electron concentration which shows a excessive amount of
carriers generated under the channel region as the power is
increased.
Each of the MPEG movies were generated with 120 samples over one
period of the fundamental (f0). This sampling rate means that there
are 60 samples over 2*f0, 40 samples over 3*f0, 30 samples over
4*f0, 24 samples over 5*f0, and 20 samples over 6*f0. The color
in the MPEG's represents the color as given in the "Color scale"
for each variable.
- MPEG Movies of Potential
(Color scale (V))
- Point 1: Pin=12.4dbm / Pout=26.0dbm
- Point 2: Pin=17.5dbm / Pout=30.0dbm
- Point 3: Pin=20.7dbm / Pout=31.7dbm
- Point 4: Pin=23.3dbm / Pout=32.5dbm
- Point 5: Pin=26.9dbm / Pout=33.2dbm
- Point 6: Pin=29.3dbm / Pout=33.6dbm
- MPEG Movies of Magnitude of Electric Field
(Color scale (V/um))
- Point 1: Pin=12.4dbm / Pout=26.0dbm
- Point 2: Pin=17.5dbm / Pout=30.0dbm
- Point 3: Pin=20.7dbm / Pout=31.7dbm
- Point 4: Pin=23.3dbm / Pout=32.5dbm
- Point 5: Pin=26.9dbm / Pout=33.2dbm
- Point 6: Pin=29.3dbm / Pout=33.6dbm
- MPEG Movies of X Component of Electric Field
(Color scale (V/um))
- Point 1: Pin=12.4dbm / Pout=26.0dbm
- Point 2: Pin=17.5dbm / Pout=30.0dbm
- Point 3: Pin=20.7dbm / Pout=31.7dbm
- Point 4: Pin=23.3dbm / Pout=32.5dbm
- Point 5: Pin=26.9dbm / Pout=33.2dbm
- Point 6: Pin=29.3dbm / Pout=33.6dbm
- MPEG Movies of Y Component of Electric Field
(Color scale (V/um))
- Point 1: Pin=12.4dbm / Pout=26.0dbm
- Point 2: Pin=17.5dbm / Pout=30.0dbm
- Point 3: Pin=20.7dbm / Pout=31.7dbm
- Point 4: Pin=23.3dbm / Pout=32.5dbm
- Point 5: Pin=26.9dbm / Pout=33.2dbm
- Point 6: Pin=29.3dbm / Pout=33.6dbm
- MPEG Movies of Electron Concentration
(Color scale log(abs(n)))
- Point 1: Pin=12.4dbm / Pout=26.0dbm
- Point 2: Pin=17.5dbm / Pout=30.0dbm
- Point 3: Pin=20.7dbm / Pout=31.7dbm
- Point 4: Pin=23.3dbm / Pout=32.5dbm
- Point 5: Pin=26.9dbm / Pout=33.2dbm
- Point 6: Pin=29.3dbm / Pout=33.6dbm
- MPEG Movies of Hole Concentration
(Color scale log(abs(p)))
- Point 1: Pin=12.4dbm / Pout=26.0dbm
- Point 2: Pin=17.5dbm / Pout=30.0dbm
- Point 3: Pin=20.7dbm / Pout=31.7dbm
- Point 4: Pin=23.3dbm / Pout=32.5dbm
- Point 5: Pin=26.9dbm / Pout=33.2dbm
- Point 6: Pin=29.3dbm / Pout=33.6dbm
Since the electron concentration seems to have the most
interesting response, one can look at
snapshots
of the electron concentration.
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Research Page for Francis Rotella