Day 22: October 23, 2013 Pass Transistor Logic ESE370: Circuit-Level Modeling, Design, and Optimization for Digital Systems Day 22: October 23, 2013 Pass Transistor Logic Penn ESE370 Fall2013 -- DeHon

Teaser What does this do? Penn ESE370 Fall2013 -- DeHon

Previously Penn ESE370 Fall2013 -- DeHon

Impact of Capacitance Penn ESE370 Fall2013 -- DeHon

Today Pass Transistor Circuits Cdiff>0 Penn ESE370 Fall2013 -- DeHon

Pass Transistor Penn ESE370 Fall2013 -- DeHon

Identify Function What function? Penn ESE370 Fall2013 -- DeHon

Area Compare with CMOS circuit? Penn ESE370 Fall2013 -- DeHon

Output What is Vout if A=0, B=0? Penn ESE370 Fall2013 -- DeHon

Output What is Vout if A=1, B=0, notB=1? Penn ESE370 Fall2013 -- DeHon

Output What is Vout if A=0.95V, B=0, notB=1? Penn ESE370 Fall2013 -- DeHon

Output Is this a restoring gate? Penn ESE370 Fall2013 -- DeHon

Output What does output look like (DC transfer)? (B=0, notB=1, sweep A) Penn ESE370 Fall2013 -- DeHon

Pass TR transfer (B=1) This is misleading. Need to be clear on how A and notA are driven, and probably look at both. (and doesn’t match question on previous slide) Penn ESE370 Fall2013 -- DeHon

CMOS Inverter Transfer Penn ESE370 Fall2013 -- DeHon

Reasonable Input to CMOS Inverter? Penn ESE370 Fall2013 -- DeHon

Pass tr xor2 with inv restore Penn ESE370 Fall2013 -- DeHon

Compare CMOS Is this a fair comparison? Penn ESE370 Fall2013 -- DeHon

Required to use? What need to add to make substitutable with CMOS? Penn ESE370 Fall2013 -- DeHon

Restore Output Penn ESE370 Fall2013 -- DeHon

Restore Output Area? (compare to CMOS) Penn ESE370 Fall2013 -- DeHon

Chain Together Penn ESE370 Fall2013 -- DeHon

Analyze Stage Penn ESE370 Fall2013 -- DeHon

Analyze Stage What’s different about this? Penn ESE370 Fall2013 -- DeHon

Delay B=0, Cdiff=0? Penn ESE370 Fall2013 -- DeHon

Equivalent RC Circuit Penn ESE370 Fall2013 -- DeHon

Circuit Penn ESE370 Fall2013 -- DeHon

Delay B=1, Cdiff=0? Penn ESE370 Fall2013 -- DeHon

Equivalent RC Circuit Penn ESE370 Fall2013 -- DeHon

Circuit Penn ESE370 Fall2013 -- DeHon

Circuit What’s different about this? Penn ESE370 Fall2013 -- DeHon

Cdiff>0 Penn ESE370 Fall2013 -- DeHon

Contact/Diffusion Capacitance Cj – diffusion depletion Cjsw – sidewall capacitance LS – length of diffusion LS Penn ESE370 Fall2013 -- DeHon

Impact of Capacitance Penn ESE370 Fall2013 -- DeHon

Inverter Delay Delay driving another inverter? Include Cdiff=gCgate W=1 Penn ESE370 Fall2013 -- DeHon

Delay B=1, Cdiff=gCg? Penn ESE370 Fall2013 -- DeHon

Equivalent RC Circuit? Penn ESE370 Fall2013 -- DeHon

Equivalent RC Circuit Penn ESE370 Fall2013 -- DeHon

Bonus (time permit) What does this do? B A More examples in book. Penn ESE370 Fall2012 -- DeHon

Idea There are other circuit disciplines Can use pass transistors for logic Sometimes gives area or delay win Penn ESE370 Fall2013 -- DeHon

Admin Project Hopefully done with baseline Spencer office hours today Get started on design-space exploration and optimization Penn ESE370 Fall2013 -- DeHon