A CMOS voltage-controlled oscillator using high-Q on-chip inductor implemented in a wafer-level package

Abstract

This paper presents a CMOS Voltage-Controlled Oscillator (VCO) with a high-Q inductor in a wafer-level package for the LC-resonator. The on-chip inductor is implemented using the redistribution metal layer of the WLP, and therefore it is called a WLP inductor. Using the thick passivation and copper metallization, the WLP inductor has high quality-factor (Q-factor). A 2nH inductor exhibits a Q-factor of 8 at 2 GHz. The center frequency of the VCO is 2.16 GHz with a tuning range of 385 MHz (18 %). The minimum phase noise is measured to be -120.2 dBc/Hz at an offset frequency of 600 KHz. The DC power consumed by the VCO-core is 1.87 mW with a supply voltage of 1.7 V and a current of 1.1 mA. The output power with a 50 Ω load is -12.5 ± 1.3 dBm throughout the whole tuning range. From the best of our knowledge, compared with recently published 2 GHzband 0.35 µm CMOS VCOs in the literature, the VCO in this work shows the lowest power consumption and the best FOM.Index Terms -CMOS, Voltage-Controlled Oscillator (VCO), Wafer-level package (WLP), inductor, quality-factor (Q-factor).