Using a Packaged Fet to Transform Between Measurement Media

The recent availability of low cost HEMT devices in an improved stripline package useful to 26GH2, though exciting for the hybrid amplifier designer, poses new measurement problems for the device supplier. Hybrid applications are most commonly in microstrip, with the leads cropped short and soldered down. Therefore using an improved version of the TTF1 or even a full lead length microstrip fixture2, the 'S' parameters as measured will differ slightly from what they will be in the customer's application. If the port isolation is sufficient, then knowing the full lead fixture and application "end effects" "3' parameters permits transforming between the two media.