5 GHz quadrature voltage-controlled oscillator using trifilar transformers

Abstract

A 0.18 mm CMOS 5 GHz quadrature voltage-controlled oscillator (QVCO) is demonstrated by using trifilar transformer coupling. The trifilar transformers composed of one primary coil and two secondary coils are used to separate the gate and drain bias for output voltage swing optimisation and also replace a conventional transistor-coupling method for quadrature output generation simultaneously. As a result, the trifilar-coupling QVCO achieves 180.1 dBc/Hz figure of merit (FOM) at the supply voltage of 1.2 V. The on-chip passive single sideband upconversion mixer is also demonstrated to fairly measure the quadrature accuracy of the QVCO. Thus, a 33.7 dB sideband rejection ratio is achieved.

100 GHz transformer‐coupled quadrature oscillator

“…On the otherhand, a transformer-coupled topology, whose signals are not coupled by active devices, can reduce the phase noise and allow low voltage operation, especially in advanced technologies. However, the transformer couples from drain to source [4,5] may degrade the cross-coupled transistor's gm by a factor of |1 + gm•jωL S |, where L S is the source inductance, and decreases the f t to limit the operating frequency. Therefore, the transformer couples from the buffer stage to the cross-coupled stage [6] can solve this issue.…”

VCO utilising bilaterally coupled transformer‐based resonator

“…Introduction: As an important component in CMOS RFIC, voltage controlled oscillator (VCOs) have been investigated deeply and broadly for a number of years. New techniques and topologies have been proposed constantly for performance improvements including lower phase noise, smaller chip size and less power consumption [1,2], or for the extended use [3,4]. One of the phase noise reduction techniques is to adopt a transformer-based resonator [1].…”