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(March 17) Fallacies of Computational Analog


Fallacies of Computational Analog


14:30, Thursday, March 17, 2016


Prof. Bang-Sup Song (UCSD)


E3-2, #1220


 As new analog techniques have been conceived in the last 30 years, analog designers have come to believe that virtually all analog functions from DC to RF can be integrated even with low power and at low voltage.  Such euphoria of superior analog performance has been mostly fueled by the aggressive device scaling down to the nanometer range.  However, in order to extend analog design capacities based only on the high-speed digital switching, the fundamentals of electronics have been often ignored.

 More often than not, time-domain, simulation-based designs end up with somewhat ambiguous and erroneous results ranging from violating the fundamental energy conservation law to obtaining instantaneous small-signal gain during brief large-signal transient period. They have veered off course with no obvious ends, which require necessary corrections. This talk raises a serious concern about such contemporary analog design practices and commonly overlooked fallacies with 10 examples from DC to RF:  

   1.  Latch with small-signal gain 

   2.  SAR consuming no power 

   3.  Analog integrate-dump and DC wandering 

   4.  Passive mixer and digital RF 

   5.  RF DAC and switching to antenna 

   6.  Inverse class-D PA 

   7.  RF transformer and high-Q PA 

   8.  Switched-capacitor DC-DC with 100% efficiency 

   9.  Single-inductor-multiple-outputs voltage regulator 

  10.  Capacitor-free LDO 


Dr. Song received his BS from SNU in 1973, MS from KAIS in 1975, and Ph.D. from UC Berkeley in 1983.  He was a member of technical staff at AT&T Bell Laboratories, Murray Hill, and was also a visiting faculty member in the EE Department of Rutgers University before he moved to the ECE Department of University of Illinois, Urbana in 1986.  He joined the faculty of the ECE Department of UC San Diego, where he is endowed with the Charles Lee Powell Chair Professor in Wireless Communication.

 Dr. Song’s research interest is in CMOS analog circuits including data converters and wireless transceivers. In his 34-year career, he has consulted 35 companies, and contributed to basic designs for digital camcorders and cameras, audio/video coder and decoders, CD/DVD players, and RF transceivers.  He made and first used standard terms such as CMOS RF, capacitor MDAC, digital calibration, background calibration, and self-trimming.