VCO_RFD_BT_RFT_AN01Application Note A Differential VCO Design for GSM Handset Applications APN1013 Introduction The differential pair of bipolar transistors is the common building block in modern RF integrated circuits. An advantage of this architecture is its high loop gain making it popular for differential Voltage Controlled Oscillator (VCO) designs in RFICs. Designers of discrete (or hybrid) VCO circuits usually use the more traditional Colpitts design avoiding the added complexity of the differential VCO configuration. Because of its primary usage in proprietary RFICs, only limited differential VCO design and modeling information has been made available. In this application note, we will attempt to build a bridge toward better understanding of the differential VCO by describing a design covering 910……