The small-signal scattering parameters and an equivalent circuit of InP junction field-effect transistors are presented. These transistors have a planar structure with the channel and gate regions formed by selective silicon and berylium implantation, respectively. The nominal channel thickness and doping are 0.2 µm and 1017cm-3and the gate length is approximately 2 µm. Typical values of transconductance and IDSSare 50 mS/mm and 150 mA/mm. Scattering parameter measurements indicate an fTof 10 GHz and anf_{\max}of 22 GHz. In-process microwave measurements are used to determine the device performance before final gate definition.