A lateral-BJT-biased CMOS voltage-controlled oscillator

A fully integrated 5 GHz differential LC-VCO using a lateral pnp current source in 250nm CMOS is presented. The lateral PNP device structure and its characteristics reviewed. The use of lateral BJT current sources in VCOs reduces flicker noise up-conversion, which is a critical need for systems with stringent close-in phase noise specifications. The VCO achieves a simulated phase noise of -93dBC/Hz at 100kHz offset and draws 4mA from a single 2.5V power supply; the VCO tuning range is 18%.