Abstract
Measurement of signal propagation delays is an important part of AC characterization of CMOS circuits. Ring oscillator based test structures are well suited for this application. The frequency of oscillation of a ring oscillator comprising a closed loop of inverting logic gates or circuit blocks is measured to obtain the signal propagation delay around the loop. If all the circuit blocks are truly identical, the delay of a single circuit block can be determined with an accuracy of <1 ps. Immunity of ring oscillator frequency to circuits external to the closed loop and the relative ease with which frequency measurements can be made have led to an extensive use of ring oscillators for technology and circuit characterization. The use of ring oscillator based test structures is further extended for tracking key MOSFET and parasitic parameters, enabling both AC and DC characterization of the same circuit elements. The currents drawn by a ring oscillator in its active and quiescent states, together with its frequency, provide useful information for establishing power and performance trade-offs in a CMOS product.
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References
Weste NHE, Eshraghian K, Smith MJS (2000) Principles of CMOS VLSI design, 2nd edn. Addison Wesley, Reading, MA
Baker RJ (2007) CMOS circuit design, layout and simulation, 2nd edn. Wiley, IEEE Press
Uyemura JP (2001) CMOS logic circuit design. Kluwer Academic, Norwell, MA
Taur Y, Ning TH (2009) Fundamentals of modern VLSI devices, 2nd edn. Cambridge University Press, New York, NY
Bhushan M, Ketchen MB (2010) Generation, elimination and utilization of harmonics in ring oscillators. Proceedings of the 2010 IEEE international conference on microelectronic test structures, 2010, pp 108–113
Bhushan M, Ketchen MB, Polonsky S, Gattiker A (2006) Ring oscillator based technique for measuring variability statistics. Proceedings of the 2006 IEEE international conference on microelectronic test structures, 2006, pp 87–93
Fuketa H, Hashimoto M, Mitsuyama Y, Onoye T (2010) Transistor variability modeling and its validation with ring-oscillation frequencies for body-biased subthreshold circuits. IEEE Trans Very Large Scale Integration (VLSI) Syst 18:1118–1129
Drego N, Chandrakasan A, Boning D (2010) All-digital circuits for measurement of spatial variation in digital circuits. IEEE J Solid-State Circuits 45:640–651
Sutherland I, Sproull B, Harris D (1999) Logical effort. Academic Press, New York, NY
Ketchen M, Bhushan M, Pearson D (2005) High speed test structures for in-line process monitoring and model calibration, Proceedings of the 2005 IEEE international conference on microelectronic test structures, 2005, pp 33–38
Ketchen M, Bhushan M (2006) Product-representative “at speed” test structures for CMOS characterization. IBM J Res Dev 50:451–468
Bhushan M, Gattiker A, Ketchen MB, Das KK (2006) Ring oscillators for CMOS process tuning and variability control. IEEE Trans Semicond Manuf 19:10–18
Bhushan M, Ketchen MB, Cai M, Kim C (2008) Ring oscillator technique for MOSFET CV characterization. IEEE Trans Semicond Manuf 21:180–185
Ketchen MB, Bhushan M, Bolam R (2007) Ring oscillator based test structure for NBTI analysis. Proceedings of the 2007 IEEE international conference on microelectronic test structures, 2007, pp 43–47
Zhou B, Khouas A (2005) Measurement of delay mismatch due to process variations by means of modified ring oscillators. IEEE international symposium on circuits and systems, ISCAS 2005, pp 5246–5249
Chan YH, Srinivasan U (2006) SRAM ring oscillator. US Patent 7,142,064,B2
Kuhn KJ (2007) Reducing variation in advanced logic technologies: approaches to process and design for manufacturability of nanoscale CMOS. IEEE international electron devices meeting, IEDM 2007, pp 471–474
Gattiker A, Bhushan M, Ketchen MB (2006) Data analysis techniques for CMOS technology characterization and product impact assessment. IEEE international test conference ITC’06, pp 1–10
Steinbrueck G, Vickers JS, Babazadeh M, Pelella MM, Pakdaman N (2009) Non-contact pad-less measurement technology and test structures for characterization of cross-wafer and in-die product variability. Proceedings of the 2009 IEEE international conference on microelectronic test structures, 2009, pp 91–95
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Bhushan, M., Ketchen, M.B. (2011). Ring Oscillators. In: Microelectronic Test Structures for CMOS Technology. Springer, New York, NY. https://doi.org/10.1007/978-1-4419-9377-9_6
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DOI: https://doi.org/10.1007/978-1-4419-9377-9_6
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