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.