Negative input resistance and real-time active load-pull measurements of a 2.5GHz oscillator using a LSNA

A large-signal measurement-based methodology to design oscillators using the Kurokawa theory is presented in this paper. Measurements of the negative input resistance and device line of a 2.5GHz HEMT oscillator versus frequency and power, and its optimization using real-time active load-pull (RTALP) for the 2
^nd
and 3
^rd
harmonics are performed with a large signal network analyzer (LSNA). As a result, the maximum output power of the oscillator is increased from 31.0mW to 38.8mW. Finally self-oscillation is verified using a load tuner to yield an output power and frequency of oscillation in reasonable agreement with the Kurokawa analysis.