Method for experimental optimization of RF matching networks
View Patent ↗An automated highly efficient “design-test-optimize” recursive loop method for experimentally optimizing embedding networks of active RF networks especially subject to wideband modulated signals, whereby the results of a matching network design are fed into the active load pull system, which synthesizes the response of the specific network design iteration and tests the transistor in real time under the emulated load conditions of the network. The weighed difference between expected and test results are used in an error function and the “design-test” loop is repeated until the error is minimized. The capacity of passive and active modulated tuners and network analysis software tools are jointly used, sharing calculated and measured data. The result of the automated optimization procedure ends into a compromise, which, if acceptable, can be processed into manufacturing with realistically expectable results.
1. An experimental verification and optimization method of the design of an active RF network at a multitude of frequencies, performed using a load pull test setup, comprises:
a network analysis algorithm,
an optimization algorithm,
a setup step, and
an execution step;
wherein
the active RF network comprises at least one active device (transistor, device under test, DUT) and at least one DUT matching network,
and wherein
the at least one DUT matching network is inserted between the at least one DUT and a load or a signal source,
and wherein
the load pull test setup comprises at least one impedance tuner and at least one test fixture housing the at least one DUT;
and wherein
the network analysis algorithm includes:
importing the configuration and parameter values of the at least one device matching network,
executing frequency domain network analysis, and
exporting network s-parameter data to the at least one impedance tuner;
and wherein
the optimization algorithm has the capacity of:
a) importing target performance and acceptance criteria of the active RF network;
b) performing the network analysis algorithm of the at least one device matching network and retrieving s-parameter data from the network analysis algorithm;
c) tuning to the at least one device matching network reflection factor s-parameter data using the at least one impedance tuner;
d) extracting measured DUT data from the load pull test setup;
e) converting the measured DUT data to active RF network data by cascading with the s-parameters of the at least one matching network;
f) comparing the active RF network data with the target performance, and
g) iterating by changing the at least one matching network configuration and parameter values, until the acceptance criteria are met, or a pre-set number of iterations is exceeded.
2. The experimental active RF network design verification and optimization method of claim 1 ,
wherein
the setup step includes:
a) defining the multitude of test frequencies and calibrating the load pull test setup;
b) mounting and biasing the DUT;
c) entering test parameters, target values, acceptance criteria and maximum number M of iterations;
d) entering matching network configuration, parameters and starting values and setting an iteration index N=1;
and wherein
the execution step includes:
e) sweeping through the frequencies of step a), computing s-parameters of the at least one matching network and exporting to the at least one impedance tuner;
f) tuning to the impedances of step e) using the at least one impedance tuner and measuring the test parameters of step c);
g) de-embedding s-parameters of the test setup and the at least one impedance tuner of steps a) and f) and embedding s-parameters of the at least one matching network of step e);
h) computing the weighed difference between the data in step g) and the target values of step c);
i) terminate if the data of step h) satisfy the acceptance criteria of step c) or if the number of iterations N reaches or exceeds M;
j) adjusting the at least one matching network configuration and parameter values, increasing the iteration index N and continuing with a next iteration in step e).
3. The experimental active RF network design verification and optimization method of claim 2 , wherein the at least one impedance tuner is an active impedance tuner capable of independently changing amplitude and phase of frequency components of a modulated signal.
4. The experimental active RF network design verification and optimization method of claim 2 , wherein the at least one impedance tuner is an active impedance tuner capable of creating reflection factor Γ up to at least |Γ|=1 at DUT reference plane.
5. The experimental active RF network design verification and optimization method of claim 2 , wherein the at least one impedance tuner is a passive slide screw impedance tuner.
6. The experimental active RF network design verification and optimization method of claim 2 ,
wherein
the network analysis algorithm comprises
a capacity for frequency domain nodal network analysis, and
a user interface for manual network configuration, parameter value control and DUT biasing adjustment.
7. The experimental active RF network design verification and optimization method of claim 2 , wherein the load pull test setup comprises an input and an output impedance tuner.
8. The experimental active RF network design verification and optimization method of claim 2 , comprising:
a passive slide screw input impedance tuner and an active output impedance tuner.
9. The experimental active RF network design verification and optimization method of claim 2 comprising:
a passive slide screw input impedance tuner and a passive slide screw output impedance tuner.
10. The experimental active RF network design verification and optimization method of claim 2 , wherein at least one impedance tuner is a harmonic impedance tuner, capable of independently controlling impedances at harmonics of a fundamental test frequency.