Novel hybrid type Automatic Amplitude Control loop VCO

This paper presents a Voltage Control Oscillator (VCO) with Automatic Amplitude Control (AAC) loop. The proposed AAC VCO employs a hybrid type AAC loop and targets the Industrial, Scientific and Medical (ISM) band applications. Detail transient analysis of this AAC VCO is derived. Based on this analysis, design steps applicable for such type of AAC loop is obtained. Measurement result shows the peak amplitude variation over the operation range of 2.65 GHz to 3 GHz is less than 9mV (without the AAC loop, amplitude variation can be as large as 40mV, or 22.2%). Phase noise achieves -123.3dBc/Hz at 1 MHz offset frequency. Power consumption of the proposed AAC VCO is 10.8 mW while the power consumed by the loop is less than 1mW.