[time-nuts] Re: [OT] MB506 pre-scaler module ??

[ed breya]

Rick, I don't see how you have the impression that any of these 
prescalers are "dynamic" dividers. I remember those dynamic divider 
circuits used in the old days to make 1 MHz and 100 kHz from 5 MHz, or 
the more modern kind based on mixers, filters, and amplifiers, to say 
make 5 from 10 Mhz, but I'm pretty sure I have never seen a 
VHF/UHF/microwave prescaler IC that was not completely static - they are 
chains of flip-flops and logic, pure and simple. The way they are 
typically used may hide their nature a bit, but they are fundamentally 
static counting machines.

Perhaps we have different definitions for dynamic vs static. My 
definition of static is that there's a unique, stable machine state for 
each possible count value, and you can stop it at any count value and 
restart it, with the right logic activity, over any period of time. The 
"right logic activity" would be to take logical control of the inputs 
rather than set them up for counting RF directly in an analog 
self-biased mode. In other words, you could put a gate in front of the 
input to control the counting.

For instance, in the data sheet for the HMC493 it says in the General 
Description:

"The  HMC493LP3  &  HMC493LP3E  are  low  noise
Divide-by-4 Static Dividers utilizing InGaP GaAs HBT
technology  packaged  in  leadless  3x3  mm  QFN  sur-
face  mount  plastic  packages.  This  device  operates
from  DC  (with  a  square  wave  input)  to  18  GHz  input
frequency from a single +5V DC supply."

The part about operating at DC "with a square wave input" means at the 
normal logic levels of the device, I'm pretty sure. And usually there's 
a minimum toggle edge speed for the various logic types, so there is a 
little bit of dynamic-ness there, if you were to try to count at very 
low rates.

Ed