Modulated S-parameter measurements for isothermal microwave device characterization

The validity of extracted microwave device models is critically dependent on the completeness, accuracy, and appropriateness of the starting device characterization data. In this letter we will present a novel technique for determining the S-parameters of a device under isothermal (i.e., no heating) operation. Additionally, this technique can be applied to determining the CW S-parameters under more extreme (e.g., forward bias/breakdown) operation. By pulse-biasing the device from the "OFF" to the "ON" state, while performing standard S-parameter measurements, resultant data is found to be characteristic of the weighted (by duty factor) scalar sum of the devices "ON"-state and "OFF"-state S-parameter(s). We will show how these measurements can then be used to interpret the devices isothermal CW S-parameters.