TABLE OF CONTENTS Byunghoo Jung and Ramesh Harjani
Department of Electrical and Computer Engineering, University of Minnesota, 200 Union Street S.E. Minneapolis, Minnesota 55455, USA harjani@ece. umn. edu
In this paper, we present a detailed analysis of VCOs using a capacitively degenerated negative resistance cell. The negative resistance cell using capacitive degeneration has a higher maximum attainable oscillation frequency and a smaller equivalent shunt capacitance when compared to the widely used cross-coupled negative- g m cell. These properties are of particular interest for the design of high-frequency and/or wide tuning range VCOs. The negative resistance provided by a traditional capacitively degenerated negative resistance cell is lower than that provided by a cross-coupled negative- g m cell. We present an active capacitive degeneration topology that overcomes this limitation. To validate this circuit topology we use two test vehicles. The first test vehicle is a 5.3 GHz VCO designed in a 0.25 ?m CMOS technology and the second test vehicle is a 20 GHz VCO designed in a 0.25 ?m BiCMOS technology. Measurement and simulation results from both test vehicles effectively demonstrate the efficacy of the capacitive degeneration technique.
Keywords: Voltage-controlled oscillators; analog integrated circuits; BiCMOS integrated circuits; capacitive degeneration; high-frequency LC oscillators; negative resistance cell.
[1]Portions of this manuscript and material referred in this manuscript have appeared in [18], [19], and [20].
Integrated LC voltage-controlled oscillators (VCOs) are critical building blocks in high-performance communication systems. The ever-increasing demand for bandwidth places very...
