S-Parameter measurements for determination of the impedance of IMPATT diodes in dependency on the current density

S-parameter measurements were performed to characterize IMPATT diodes integrated in coplanar waveguides, up to a maximum frequency of 40GHz. With a de-embedding procedure the real- and imaginary part of the impedance of the inner diodes were calculated. Above the avalanche frequency the diodes showed the expected negative real- and imaginary parts of the impedance. Due to theory, with increasing current density the avalanche frequency shifted to higher values. To manufacture the diodes and oscillators a complete monolithically integrated process was used. This process avoids the use, of heatsinks and the difficult and time consuming bonding process.