1. Home
  2. Electronics Design
  3. Holy wasted opamps Batman.
  4. Page 4

Holy wasted opamps Batman.

Transistors are free. Resistors and capacitors are expensive ;-)

(I just merged two ideas from Gardner.) ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| STV, Queen Creek, AZ 85142    Skype: skypeanalog |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 

Why is it that the most unproductive members of our society blame 
the most productive members of our society for their failures?
Reply to
Jim Thompson
Loading thread data ...

How do you do that? If you start an oscillator with a -random phase with respect to the crystal oscillator, then lock the oscillator to the crystal, the phase has to shift and you lose the initial phase. How do you keep the start/stop oscillator edges time-coherent to the trigger?

There are a number of excellent papers on bang-bang pll loops. Here are some:

formatting link
formatting link

(unfortunately, my link to the zip executable no longer works. I could upload it if you like)

Verification of Bit-Error Rate in Bang-Bang Clock and Data Recovery Circuits Ken Kundert

formatting link

Richard Walker has a number of papers on bang-bang loops. Search "bang- bang"

formatting link

Many more references online.

Reply to
Steve Wilson

There are a few techniques. The Hewlett Packard 5359A Time Synthesizer used a triggered ECL delay-line oscillator which was synchronized to a crystal oscillator using a heterodyne phaselock technique. The manuals are available online. Several people copied that idea. My trick is to have an ADC that's clocked by the XO and that samples/observes the waveform of the triggered oscillator. An FPGA looks at the ADC data stream, figures out the phase relationship, and locks that in, with a DAC/varicap on the triggered oscillator. Done carefully, the error is low picoseconds.

I'm not doing a b-b loop now, but I'll save those in case I do again.

--

John Larkin         Highland Technology, Inc 

lunatic fringe electronics
Reply to
John Larkin

Thanks. That helps a lot.

It looks like I got snookered. Apparently there are several PLLSim programs with the same name, and the one I have is for a conventional charge pump PLL. It looks useful in it's own right, but it's not a bang-bank.

I' trying to track down the authors of the original program and will update if successful.

Reply to
Steve Wilson

How does positive feedback make the filter oscillate and not latch?

Reply to
Tom Del Rosso

There are two methods. The one I like is to use an auxiliary Schmitt trigger to pull the input a millivolt or so off the null. That gives you a nice triangle sweep and works with any sort of loop filter. (I posted a circuit like that upthread.)

The other one is to use a Wien-bridge style network. That doesn't need the extra amp, but it complicates the filter design. Since an LM358 is better than good enough for the Schmitt, it seems like a no-brainer.

Cheers

Phil Hobbs

Reply to
pcdhobbs

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.