Title :
A Darlington-Enhanced CMOS Oscillator Architecture
Author :
Lehtonen, Tapio A. ; Ruippo, Pekko ; Keitaanniemi, Teppo ; Tchamov, Nikolay T.
Author_Institution :
Dept. of Commun. Eng., Tampere Univ. of Technol., Tampere, Finland
Abstract :
A fully differential CMOS oscillator using Darlington composite pMOS transistors is presented. The composite transistor structure increases gain of the negative-Gm stage for a reliable startup and improves device reliability due to use of high-voltage transistors. To achieve good phase noise available with large voltages and the speed of small active devices in a modern CMOS process, a higher (2.8 V) power supply requiring a combination of low- and high-voltage transistors is used. In addition, the oscillator uses negative feedback to reduce amplitude variation due to LC-tank loading. Circuit functionality is confirmed with a test circuit fabricated in a standard 130-nm CMOS process. The oscillator reaches a phase noise better than -121.2 dBc/Hz at 1-MHz offset across a tuning range of 3015 to 5298 MHz while consuming a less than 10.6-mA current from a 2.8-V power supply.
Keywords :
CMOS integrated circuits; LC circuits; MMIC oscillators; feedback; field effect MMIC; integrated circuit reliability; microwave bipolar transistors; CMOS process; Darlington composite pMOS transistor; LC tank loading; amplitude variation; composite transistor structure; darlington enhanced CMOS oscillator architecture; device reliability; frequency 3015 MHz to 5298 MHz; fully differential CMOS oscillator; high voltage transistor; negative Gm stage; negative feedback; phase noise; size 130 nm; voltage 2.8 V; CMOS integrated circuits; Phase noise; Q factor; Transistors; Tuning; Voltage-controlled oscillators; Amplitude regulation; Darlington; composite; feedback; oscillator; voltage-controlled oscillator (VCO); wideband;
Journal_Title :
Circuits and Systems II: Express Briefs, IEEE Transactions on
DOI :
10.1109/TCSII.2011.2177699