Analysis and design of wideband distributed VCOs based on switched-cells tuning technique

The paper discusses a VCO belonging to the class of Distributed-VCOs (DVCOs) designed for wide tuning range operations. The trade-off between wide bandwidth and phase noise is central to the proposed design and the paper covers the DVCO topology and discusses its operations in detail, starting by the general conditions of oscillation and covering the applied tuning techniques. In particular the paper reports a description of the so called “switched-cells tuning technique”. The design of a fully integrated DVCO is reported. It is based on the “switched-cells tuning technique” and provides the following measured tuning ranges over four sub-bands: 219 MHz around 900, 291 MHz around 1.5 GHz, 392 MHz around 1.8 GHz and 199 MHz around 2.4 GHz. The DVCO performances are discussed and compared with other similar implementation reported in the recent literature showing the potentialities of the proposed approach. According to the reported theory, the results show the applicability of the proposed Distributed VCOs for wide bandwidth applications.