Wide band LC VCO with automatic amplitude controller for IEEE 802.22 cognitive radio receiver

This paper deals with the design of an LC Voltage Controlled Oscillator (LC VCO) with and without an Automatic Amplitude Controller (AAC). In order to achieve a wide band tuning range specified in IEEE 802.22 the VCO core incorporates a Switched Capacitor Array (SCA). An amplitude controlling technique is used to stabilize the oscillation amplitude over the frequency band. The LC VCO with an AAC circuit achieves 63% of tuning range and displays phase noise levels from -126.2 dBc/Hz to -122.67 dBc/Hz at 1 MHz frequency offset within the entire tuning range. The average power consumption of the oscillator with an AAC is 21 mW.