Analysis and design for millimeter-wave PHEMT VCO in time domain

In this paper a Ka-band microstrip PHEMT VCO is analyzed and designed for output power and oscillating frequency in the time domain using a nonlinear transistor model. The microstrip is lumped into inductors and capacitors for analysis. Making use of the nonlinear transistor model and its parameters, the state equation of the lumped equivalent circuit of the VCO is founded. The state equation is solved by computer simulation with PSPICE or MicroSim. Utilizing the result of simulation, transient and steady-state process of the VCO under the given initial conditions can be understood and a Ka-band PHEMT VCO is designed.