Calibration of a real-time load-pull system using the generalized theory of the TRM technique

The thru-reflect-match (TRM) calibration technique uses as calibration structures a thru, a pair of highly reflecting loads and two loads of impedance close to the measuring system impedance (Z₀). In practice, the loads used as match standard may be nonsymmetrical and of impedance different from Z₀. By using the ABCD-parameters matrix formalism, in this paper the calibration of a load-pull system is carried out by using a generalized theory of the TRM technique, allowing the use of nonsymmetrical loads of arbitrary impedance. The impact of ignoring the asymmetry and frequency-dependent impedance of the loads used as match standard on the determination of the load-pull contours of constant output power is investigated.