Abstract
In this paper, we evaluate the high-frequency performance limitations of traditional LC voltage-controlled oscillators (VCOs) that use a cross-coupled negative resistance cell and propose a new topology that overcomes these limitations. The proposed cell is based on a capacitively emitter degenerated topology which uses a cross-coupled MOS pair as the degeneration cell. The cross-coupled MOS pair contributes additional conductance and results in a higher maximum attainable oscillation frequency and better negative resistance characteristics as compared to the other topologies at high frequencies. These properties combined with its small effective capacitance enable low-power low-noise high-frequency VCO implementations. The proposed topology is demonstrated through a 20-GHz fully integrated LC VCO implemented in the IBM SiGe 0.25-μm BiCMOS process. A comparison of its figure of merit with previously reported 20-GHz VCOs shows the effectiveness of the proposed topology.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 2359-2370 |
| Number of pages | 12 |
| Journal | IEEE Journal of Solid-State Circuits |
| Volume | 39 |
| Issue number | 12 |
| DOIs | |
| State | Published - Dec 2004 |
Bibliographical note
Funding Information:Manuscript received April 16, 2004; revised July 16, 2004. This work was supported in part by a grant from the Semiconductor Research Corporation. The authors are with the University of Minnesota, Minneapolis, MN 55455 USA (e-mail: harjani@ece.umn.edu). Digital Object Identifier 10.1109/JSSC.2004.835643
Keywords
- Analog integrated circuits
- BiCMOS integrated circuits
- Capacitive degeneration
- High-frequency LC oscillators
- Negative resistance cell
- Voltage-controlled oscillators (VCOs)