eldo_user

Optimization
Designing a Low Noise Amplifier (LNA)
Optimization Results
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Section 1 - Statistics and Diagnostics
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==> Number Of Iterations 84
Number Of Simulations 850
Merit Function
Optimality
Feasibility
4.8781332e+00
7.55e-03
0.00e+00
The term Optimality was denoted by OPTIM(x) in the definition of the TOL_GRAD parameter
of the .OPTIMIZE command. A small value indicates that the optimality condition is satisfied.
The term Merit Function is the value of the function minimized during the optimization process.
This function can be considered as a global score associated to the final iterate, that is, it gives
the distance of the final solution to the ideal solution (which may not exist). For the LNA
problem, the ideal solution would have given a Merit Function value close to 4.0, since the four
error functions coming from the objectives AV_DB@2.4GHZ, AV_DB@2.5GHZ,
S11_DB@2.4GHZ and S11_DB@2.5GHZ would be exactly zero, and the four MINIMIZE
objectives should be close to 1.0.
Optimization Results
The design variables found by the optimizer provide a voltage gain close to 20dB, a return loss
of 12dB, and an IIP3 of 1.2dBm. Note that the value of the Noise Figure (NF) is not so similar
to the value of the Minimum Noise Figure (NFMIN). Thus the noise matching can be improved,
however, this maybe at the expense of S11 matching by using different weighting numbers for
each of the objectives.
Table 13-5 gives the results of optimization for the GOAL objectives:
Table 13-5. Results of Optimization for GOAL Objectives
Name
Initial Value Current Value Goal Value
AV_DB@2.4GHZ 11.9 20.1 20.0
AV_DB@2.5GHZ 11.7 19.6 20.0
S11_DB@2.4GHZ -0.82 -15.1 -15.0
S11_DB@2.5GHZ -0.88 -15.1 -15.0
The results reported in the previous table have been obtained with the default values (1.0) of the
WEIGHT parameters.
The results for MINIMIZE objectives are shown in Table 13-6:
Eldo® User's Manual, 15.3 667