A FR4‐based compact VCO with wide tuning range using SISL transformed triple‐tanks

Abstract

This work proposes a compact voltage-controlled oscillator (VCO) using the transformer-based triple-tanks on substrate integrated suspended line (SISL) platform for 5G applications. In order to broaden the tuning range, the varactors are loaded on the second tank to avoid the effect of parasitic capacitance of bipolar junction transistors (BJTs) on the tuning range, and compact transformed triple-tanks are designed to decrease the parasitic capacitance. By using a compact transformed triple-tanks and double layers wiring technology, the core circuit area is only 0.1λg × 0.1λg, which is the smallest among the reported board-level VCOs. Although the low-cost FR4 is chosen, the phase noise is still acceptable by adopting cross-coupled topology and multi-tanks technology. The measured results show that the VCO exhibits a wide tuning range of 28.9% from 2.88 to 3.85 GHz, and the best phase noise is –119.45 dBc/Hz @1 MHz at 3.76 GHz.