Transformer Based Oscillators Adesh Garg Outline Why use
Transformer Based Oscillators Adesh Garg
Outline Why use a Transformer instead of an Inductor? } What is a Monolithic Transformer? } § § § } Physical Layout Equivalent Model Electrical Characteristics Application of Transformers to Oscillator § Ring Oscillator § LC Tank Oscillator } References
Transformers Replacing Inductors } Inductors tend to have. . . § Low quality factor (Q) Highly Lossy § Lack Tunability § Large amounts of Chip area } Transformers have been used to correct the above short coming [1 -5]
What is a Monolithic Transformer? } Physical Layout
![What is a Monolithic Transformer? } Equivalent Model [1]](http://slidetodoc.com/presentation_image_h/0b489a9b5d42550c2eed968ee146cd70/image-5.jpg "What is a Monolithic Transformer? } Equivalent Model [1]")
What is a Monolithic Transformer? } Equivalent Model [1]
What is a Monolithic Transformer? } Electrical Characteristics § The coupling between stages for typical process is usually between 0. 75 < Km < 0. 9 [1] Largely dependant on width and spacing of the metal traces § Depends on layout and structure. Different benefits for different architecture [1][2] Coupling, Resonance, Loses, Symmetry
Background: Types of Oscillators } Ring Oscillator § Uses the delay between stages to determine Oscillator’s frequency (either transmission lines or lumped delays). } LC Tank Oscillator § Uses Inductor and Capacitor to determine Oscillator’s frequency
![Ring Oscillator [3] } Ring Oscillator § Inductively Tuned](http://slidetodoc.com/presentation_image_h/0b489a9b5d42550c2eed968ee146cd70/image-8.jpg "Ring Oscillator [3] } Ring Oscillator § Inductively Tuned")
Ring Oscillator [3] } Ring Oscillator § Inductively Tuned
![LC Tank VCO [4] Transformer used to change impedance of resonator tank. } Improves](http://slidetodoc.com/presentation_image_h/0b489a9b5d42550c2eed968ee146cd70/image-9.jpg "LC Tank VCO [4] Transformer used to change impedance of resonator tank. } Improves")
LC Tank VCO [4] Transformer used to change impedance of resonator tank. } Improves Q factor for equivalent inductor of similar size } § Phase Noise improvement
![LC Tank VCO [4] cont…](http://slidetodoc.com/presentation_image_h/0b489a9b5d42550c2eed968ee146cd70/image-10.jpg "LC Tank VCO [4] cont…")
LC Tank VCO [4] cont…
Conclusion Transformers are relatively new and their application to tuned circuits have only begin to be explored } I expect to see continued research in this field and the use of transformers for RF circuit like the oscillator }
![References } } } [1] John Long, “Monolithic transformers for silicon RF IC design,](http://slidetodoc.com/presentation_image_h/0b489a9b5d42550c2eed968ee146cd70/image-12.jpg "References } } } [1] John Long, “Monolithic transformers for silicon RF IC design,")
References } } } [1] John Long, “Monolithic transformers for silicon RF IC design, " IEEE J. of Solid State Cir. , vol. 35, no. 9, pp. 1368 -1382, September 2000. [2] Alireza Zolfaghari, Andrew Chan, and Behzad Razavi, “Stacked inductors and transformers in cmos technology, " IEEE J. of Solid State Cir. , vol. 36, no. 4, pp. 620 -628, April 2001. [3] John Long and Raymond Koo, “An inductively-tuned quadrature oscillator with extended frequency control range, " in Proceedings of the 2003 International Symposium on Circuits and Systems, 2003, vol. 1, pp. 25 -28. [4] Matt Straayer, Jose Cabanillas, and Gabriel Rebeiz, “A low-noise transformer-based 1. 7 ghz cmos vco, " in IEEE International Solid-State Circuits Conference Proceedings, Feb 2002, 17. 1. [5] Bogdan Georgescu, Holly Pekau, James Haslett, and John Mc. Rory, Tunable coupled inductor q-enhancement for parallel resonant LC tanks, " IEEE Transactions on Circuits and Systems-II: Analog and Digital Signal Processing, vol. 50, no. 10, pp. 705 -713, October 2003.
References cont… } } John Long and David Cassan, A 1 -v transformer-feedback low-noise amplifier for 5 -ghz wireless LAN in 0. 18 um CMOS, " IEEE J. of Solid State Cir. , vol. 38, no. 3, pp. 427 -435, March 2003 John W. M. Rogers and Calvin Plett, “A 5 -ghz radio front-end with automatically Q-tuned notch filter and vco, " IEEE J. of Solid State Cir. , vol. 38, no. 9, pp. 1547 -1554, September 2003.
- Slides: 13