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) |
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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 1 2004 |
Keywords
- Analog integrated circuits
- BiCMOS integrated circuits
- Capacitive degeneration
- High-frequency LC oscillators
- Negative resistance cell
- Voltage-controlled oscillators (VCOs)