2.6 A 190.5GHz mode-switching VCO with 20.7% continuous tuning range and maximum power of −2.1dBm in 0.13µm BiCMOS

Abstract

Wideband mm-Wave and terahertz (THz) applications, including high data-rate communications, high-resolution radar and spectroscopy, require wideband signal sources. Nevertheless, low quality factor of varactors and lossy switches in addition to relatively large parasitic capacitors of transistors have been limiting the tuning range of voltage controlled oscillators (VCO) at these frequencies. To overcome these challenges, harmonic VCOs using high harmonic numbers and switched-capacitor banks at much lower fundamental frequencies were reported [1]. The drawback to this approach is the limited output power since the extracted harmonic number is typically high. Other tuning techniques such as phase/delay control between coupled oscillators and tuning boosting using transformer-based resonators were also reported [2–4]. However, the highest reported tuning range for VCOs above 150GHz is not more than 12.5%, which covers a small portion of the bandwidth available at high mm-Wave and THz frequencies.