A 24 GHz Indirect VCO in 0.18 μm CMOS Technology

A 24 GHz LO signal is generated indirectly by proposing a 12 GHz VCO followed by an active mixer which acts as a frequency doubler. This technique improves the tunability and reduces the power consumption of the VCO/Active doubler compared to a stand-alone VCO at 24 GHz considerably while providing the same amount of phase noise. The circuit is implemented in 0.18 mu m CMOS technology. The resulted indirect VCO has 20 % tuning range, 15 mW power consumption, -8.5 dBm output power and a phase noise around -100 dBc/Hz @ 1 MHz offset for a 23.5 GHz carrier. This VCO is suitable for use in low power 24 GHz PLLs and also direct conversion receiver applications.