An 180 nm CMOS single inverter 2.4 GHz LC oscillator

The LC oscillator is one type of harmonic oscillator that can be designed to generate single-ended, differential or quadrature signals. The oscillator that we have developed is a single-ended LC oscillator using only one inverter, one inductor and one capacitor in its tank circuit. The 2.4 GHz oscillator is realized using Silterra´s industry standard 180 nm RF CMOS fabrication technology. The single-ended single inverter LC oscillator is actually half of the typical differential cross-coupled LC oscillator with an additional RC start-up circuit. The LC oscillator output is connected to an on-chip dynamic prescaler that divides by 14, followed by a static binary frequency divider that divides by 256. The mean measured oscillator frequency is 2.098 GHz, about 12% lower than expected. This difference is due to parasitic interconnect capacitance in the circuit. The frequency of the 18 oscillators has a very small sigma of 0.514%. The oscillator frequency shows very little dependence on temperature.