Multi-mode voltage-controlled oscillator (VCO) with transformer-based coupling

Abstract

Techniques and apparatus for oscillating signal generation using a multi-mode voltage-controlled oscillator (VCO) circuit with transformer-based coupling. An example VCO circuit generally includes a first pair of transistors associated with a first active negative transconductance circuit; a second pair of transistors associated with a second active negative transconductance circuit; a transformer comprising a primary winding and a secondary winding, the primary winding being coupled to the second pair of transistors; a first set of switches coupled between gates of the first pair of transistors and the secondary winding of the transformer; and a second set of switches coupled between the gates of the first pair of transistors and a first voltage node.