Large-signal analysis of MOS varactors in CMOS -G/m/ LC VCOs
MOS varactors are used extensively as tunable elements in the tank circuits of RF voltage-controlled oscillators (VCOs) based on submicrometer CMOS technologies. MOS varactor topologies include conventional D = S = B connected, inversion-mode (I-MOS), and accumulation-mode (A-MOS) structures. When i...
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| Published in: | IEEE journal of solid-state circuits Vol. 38; no. 8; pp. 1325 - 1332 |
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| Main Authors: | , |
| Format: | Journal Article |
| Language: | English |
| Published: |
01-08-2003
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| Online Access: | Get full text |
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| Summary: | MOS varactors are used extensively as tunable elements in the tank circuits of RF voltage-controlled oscillators (VCOs) based on submicrometer CMOS technologies. MOS varactor topologies include conventional D = S = B connected, inversion-mode (I-MOS), and accumulation-mode (A-MOS) structures. When incorporated into the VCO tank circuit, the large-signal swing of the VCO output oscillation modulates the varactor capacitance in time, resulting in a VCO tuning curve that deviates from the dc tuning curve of the particular varactor structure. This paper presents a detailed analysis of this large-signal effect. Simulated results are compared to measurements for an example 2.5-GHz complementary -G/m/ LC VCO using I-MOS varactors implemented in 0.35-mum CMOS technology. |
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| Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
| ISSN: | 0018-9200 |
| DOI: | 10.1109/JSSC.2003.814416 |