Circuit Contest - Last Day

Humm what is this, anything and everything? How about this then?

Tim

-- Deep Fryer: a very philosophical monk. Website:

Sawtooth oscillator (freq set by Rt-Ct ramp, hysteresis comparator, and discharge) plus PWM-generator comparator.

Sig in and PWM output. Yawn.

Yeah, but it's tube, and I'd like some precise numbers. ;-)

Tim

-- Deep Fryer: a very philosophical monk. Website:

Fine, then get busy and do the work, we're not going to. ;-)

You might not have many responses, but I'm sure I'm not the only person waiting to be enlightened, whose curiosity was aroused by one or other of the circuits. I puzzled over the logic buffer circuit for a while, but I couldn't fathom its purpose: speeding up the edges? Slowing down the edges?? Controlling the thresholds??? So I hope you're going to educate us in due course.

I couldn't even find the file, so clearly I was out of it. : )

Yes, I will post functional descriptions in a few days.

...Jim Thompson

Originally posted to A.B.S.E with an announcement on S.E.D to go to A.B.S.E

When many didn't get A.B.S.E on their servers I also announced and posted a URL...

...Jim Thompson

That's fine, we can design you one, but you'll have to linearize it. :-)

Yep- that's about right. Maybe you should try changing the angle of this "contest" to invention instead of straightforward circuit analysis. The ignorant losers, who comprise the majority of SED, will be self-excluded still, but the competent enthusiasts at all levels can compete.

Well. I need a bandgap that will run on +1.62V, from -55°C to +125°C, CMOS process with parasitic substrate PNP's ;-)

...Jim Thompson

I hope you weren't including me in that list. I can readily tell what all three circuits do, and think I could correctly analyze 95 to 100% of the circuitry, but I also see it'd be a bit more time- consuming than I'd like to spend right now. And frankly, not that much fun either. I'm also unsure of what some of the intrinsic capacitance values are. Sorry, Jim.

I do like your obsessive use of mirrors, that simplifies analysis.

A bandgap is supposed to be flat over temperature and VDD ;-)

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |

--- ^^^^^^^^

Operative word. Perfectly flat.

It IS primarily for educational purposes, although an ulterior motive lurked in the back of my head... demonstrate that several of the key noise-makers lurking here are blow-hards ;-)

(NONE of the key noise-makers submitted a circuit analysis.)

...Jim Thompson

I should have added, ALL three of the circuits were really quite simple, except for being typically monolithic... using lots of devices to ensure matching and good temperature behavior, and with current mirrors out the kazoo. The functions they performed should have been "intuitively obvious to the most casual observer" ;-)

...Jim Thompson

John, John, John.

I need to carefully read over the three rational submissions and then decide. (I had one very irrational submission from guess who ?:-)

I purposefully refrained from more than glancing at the submissions as they arrived. Since this is basically an "essay" question I want to read all in one sitting so that I'm fair... "grading on the curve" ;-)

...Jim Thompson

No.

Those don't really need to enter into a general analysis. It should be obvious that they're there for loop compensation.

...Jim Thompson