Analysis of varactor multipliers with idlers

A large-signal analysis of varactor harmonic generators with idlers is presented. The analysis is valid for both abrupt junction and graded junction varactors and any value of Q-factor. Numerical results are given for the cases of triplers and quadruplers operating with a second harmonic idler. The analysis uses a Fourier expansion for the voltage across the varactor in terms of the currents flowing (restricted to input, output and selected harmonic frequencies). The results include optimum generator and load resistances as a function of the operating efficiency. The advantage in terms of efficiency of using idlers is demonstrated.