M niknejad and b boser 28 custom mom capacitors metal

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Unformatted text preview: ften loads amplifier increased load adds power dissipation EECS 240 Lecture 2: CMOS - passive devices © 2006 A. M. Niknejad and B. Boser 27 MIM Capacitors • Many processes have add-on options such as a MIM capacitor. • This is simply a metal-insulator-metal (MIM) structure situated in the oxide layers. The insulator is a very thin layer (~25 nm), resulting in high density and relatively low back-plate parasitics. EECS 240 Lecture 2: CMOS - passive devices © 2006 A. M. Niknejad and B. Boser 28 Custom “MOM” Capacitors • Metal-Oxide-Metal capacitor. Free with modern CMOS. • Use lateral flux (~Lmin) and multiple metal layers to realize high capacitance values EECS 240 Lecture 2: CMOS - passive devices © 2006 A. M. Niknejad and B. Boser 29 MOM Capacitor Cross Section • Use a wall of metal and vias to realize high density. • Use as many layers as possible. Use fewer layers to minimize backplate parasitics. • Reasonably good matching and accuracy. EECS 240 Lecture 2: CMOS - passive devices © 2006 A. M. Niknejad and B. Boser 30 Commercial BiCMOS Process www.ibm.com/chips/techlib/techlib.nsf/techdocs/FE154539B8C4C01687256CD9007346D7/$file/180-nmCMOS3-24-04.pdf EECS 240 Lecture 2: CMOS - passive devices © 2006 A. M. Niknejad and B. Boser 31 Typical 180nm CMOS www.ibm.com/chips/techlib/techlib.nsf/techdocs/FE154539B8C4C01687256CD9007346D7/$file/180-nmCMOS3-24-04.pdf • Leff < L • High volage IO devices • High voltage device has thick oxide EECS 240 Lecture 2: CMOS - passive devices © 2006 A. M. Niknejad and B. Boser 32 Triple Well Option n-well p-well deep n-well p-sub • Many modern process have a triple well (deep well) option that allows NFETs to be isolated from the substrate. Older notation: twin-well. • This provides better immunity from digital noise in a mixed signal circuit. EECS 240 Lecture 2: CMOS - passive devices © 2006 A. M. Niknejad and B. Boser 33 Isolation Options www.ibm.com/chips/techlib/techlib.nsf/techdocs/FE154539B8C4C01687256CD9007346D7/$file/180-nmCMOS3-24-04.pdf EECS 240 Lecture 2: CMOS - passive devices © 2006 A. M. Niknejad and B. Boser 34 Bipolar Devices www.ibm.com/chips/techlib/te...
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This note was uploaded on 03/18/2014 for the course EECS 240 taught by Professor Boser during the Spring '04 term at University of California, Berkeley.

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