High performance VCO for VHF air-band transceiver

A new complementary junction field effect transistor (JFET) voltage-controlled oscillator (VCO) is presented for VHF band. The VCO circuit provides almost linear negative differential resistance (NDR) region that can be precisely set with three external resistors. Mathematical model of the VCO is developed. The model is investigated theoretically and by Spice simulation. The theoretical concepts are verified by designing a VCO for VHF air band transceiver, which covers the frequency band between 103.1 and 169.5 MHz At a 3-V power supply and power consumption 12 mW, the designed VCO has a phase noise of -124 dBc/Hz at 10 kHz offset from carrier and achieves a very good figure of merit (FOM) performance of -196 dBc/Hz.