An Active Inductor-Based Differential Ring VCO with Wide Tuning Range for UWB Applications

In this paper, a wide band differential ring Voltage-Controlled Oscillator (VCO) using a composite load and dual-delay-path technique is presented. This topology consists of four delay stages connected in a ring structure. The proposed delay cell utilizes a pre-discharge path to output nodes to enhance the oscillation frequency. Also, a Lin-Payne active inductor as a composite is used load to provide a large tuning frequency range, while the differential topology of the cell improves the phase noise performance. The presented circuit is designed and simulated using standard 180 nm CMOS technology with a 1.8 V power supply (V
DD
). The center frequency of the proposed ring VCO is 3.5 GHz, and the output frequency of the signal can be varied from 1.87 GHz to 5.2 GHz (over a 3 GHz tuning range) by adjusting the control voltage
$(\mathrm{V}_{\text{Tun}\mathrm{e}})$
from 1.3 V to 0 V. Over this range of frequency, the power consumption ranges from 0.77 mW to 2.84 mW, achieving a phase noise of −86.5 dBc/Hz at 1 MHz. The output oscillation signal swing ranges from 0.15 V to 1.55 V peak-to-peak, and the overall Figure of Merit (FoM) is −154.83 dBc/Hz at 1 MHz. Furthermore, corner, temperature, Monte Carlo, and other analyses have been conducted to demonstrate the reliability of the design.