Promax MO-180 Manual De Usuario página 102

The maximum quantisation error for the P
dB. The maximum quantisation error for the G
0.001 dB. Finally, the maximum quantisation error for the φ
0.003°.
Figure 4 shows the region of the complex plane containing all the valid
correction gains. The separation between the arcs spanning 60° is 0.1 dB.
Figure 4: Valid range for the quantised complex correction gains (divided by 32768).
In the following we present another example of how to calculate the complex
correcting gains for an RF amplifier modelled using Saleh's model
model a simple two-parameter function is used to model the AM-AM and AM-PM
characteristics of non-linear amplifiers. It was originally developed for TWTA's, but an
appropriate selection for the amplitude and phase coefficients (α's and β's) provide a
suitable model for solid state amplifiers as well.
The AM-AM and AM-PM functions are defined by:
where r is the instantaneous envelope of the signal at the input to the amplifier
(envelope power is therefore r
conversion in degrees.
3
A.A.M. Saleh, "Frequency-independent and frequency-dependent nonlinear models of TWT amplifiers", IEEE Trans.
Communications, vol. COM-29, pp.1715-1720, November 1981.
Page 32
's for a resolution of 0.1 dB is less than
n
α
r
= a
A ) ( r
2
+ β
1 r
a
2
α
r
φ
Φ =
r
) (
2
+ β
1 r
φ
), A(r) is the AM-AM conversion and Φ(r) is the AM-PM
2
USER'S MANUAL MO-180
's with 0.1 dB of resolution is 0.02
n
's with 0.1° of resolution is
n
3
. In this type of
04/2008