Time-Varying Root-Locus of Large-Signal LC Oscillators

Time-varying root-locus of a large-signal
LC
oscillator is obtained via semi-symbolic analysis, where the complex frequency
s
is a symbol. The steady-state circuit behavior is modeled by its time-varying small-signal admittance matrix within one oscillation period. The roots of the characteristic equation are computed with the QZ method. The time-varying root-locus analysis capabilities are demonstrated on a GHz range 130 nm complementary metal-oxide-semiconductor cross-coupled
LC
oscillator, and they complement the results obtained with the traditional numerical computer-aided design methods.