super fast divide-by-N

Hello,

I am looking for a fast divide-by-N chip with a high bandwidth. I'm hoping 
for an input frequency of 1 GHz but would probably settle for one around 80 
MHz. Duty cycle doesn't matter for the DSP application I have in mind but I 
do need to run at 3V.

Thanks to anyone who knows of one and cares to share,

Thomas 

On Tue, 16 Aug 2005 18:30:36 GMT, "Thomas Magma"
<somewhere@overtherainbow.com> wrote:

>Hello,
>
>I am looking for a fast divide-by-N chip with a high bandwidth. I'm hoping 
>for an input frequency of 1 GHz but would probably settle for one around 80 
>MHz. Duty cycle doesn't matter for the DSP application I have in mind but I 
>do need to run at 3V.
>
>Thanks to anyone who knows of one and cares to share,
>
>Thomas 
>

http://www.azmicrotek.com/

                                        ...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  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

> http://www.azmicrotek.com/
>

Thanks Jim,

Nice parts but I can only see a divided by 2 and divided by 4 from that 
company. I'm kind of looking for a divide by N. Maybe up to 32 or so.

Thanks,
Thomas 

Once you have divided by 2 or 4, you are in the realm of fast logic
(look at the various fast logic families).

One search I would suggest is 'fast prescalers'.

Jim has set you on the right path :)

Cheers

PeteS

Thomas Magma wrote:
>>http://www.azmicrotek.com/
>>
> 
> 
> Thanks Jim,
> 
> Nice parts but I can only see a divided by 2 and divided by 4 from that 
> company. I'm kind of looking for a divide by N. Maybe up to 32 or so.
> 

Above, you imply that there are only 32 values of N (1-32).  Can you 
multiply by 1/N instead?


-- 
Jim Thomas            Principal Applications Engineer  Bittware, Inc
jthomas@bittware.com  http://www.bittware.com    (603) 226-0404 x536
Sometimes experience is the only teacher that works - Mike Rosing

Thomas Magma wrote:

> 
> 
>> http://www.azmicrotek.com/
>>
> 
> Thanks Jim,
> 
> Nice parts but I can only see a divided by 2 and divided by 4 from that
> company. I'm kind of looking for a divide by N. Maybe up to 32 or so.
> 
> Thanks,
> Thomas

The important number is what is the minimum divide ratio that you need.  If
the minimum N is a reasonably large number then you can use the
conventional approach used in RF synthesisers, where you have a fast
prescaler (e.g. divide by 8 or 9) and then a slower block of logic that
decides when to switch the prescaler into divide by 8, and when to use
divide by 9.

You might be able to find a RF synth chip where the divider output is
available at a pin.  Look at the Analog Devices ADF4111 for example which
can mux out the divider output to a pin.

Chris

Thomas Magma wrote:
> Hello,
> 
> I am looking for a fast divide-by-N chip with a high bandwidth. I'm hoping 
> for an input frequency of 1 GHz but would probably settle for one around 80 
> MHz. Duty cycle doesn't matter for the DSP application I have in mind but I 
> do need to run at 3V.

That's a pretty broad range, Thomas. Like me asking a bank for a loan of 
$1,250 and saying I'll settle for a dollar.

Jerry
-- 
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������

>Can you multiply by 1/N instead?

Ah...yes?... I don't quite know what you mean here. I can see how they are 
equal mathematically, but I don't know how to achieve this with electronics.


"Jim Thomas" <jthomas@bittware.com> wrote in message 
news:11g4lnbjuad2578@corp.supernews.com...
> Thomas Magma wrote:
>>>http://www.azmicrotek.com/
>>>
>>
>>
>> Thanks Jim,
>>
>> Nice parts but I can only see a divided by 2 and divided by 4 from that 
>> company. I'm kind of looking for a divide by N. Maybe up to 32 or so.
>>
>
> Above, you imply that there are only 32 values of N (1-32).  Can you 
> multiply by 1/N instead?
>
>
> -- 
> Jim Thomas            Principal Applications Engineer  Bittware, Inc
> jthomas@bittware.com  http://www.bittware.com    (603) 226-0404 x536
> Sometimes experience is the only teacher that works - Mike Rosing 

Thomas Magma wrote:

> Hello,
> 
> I am looking for a fast divide-by-N chip with a high bandwidth. I'm hoping 
> for an input frequency of 1 GHz but would probably settle for one around 80 
> MHz. Duty cycle doesn't matter for the DSP application I have in mind but I 
> do need to run at 3V.
> 
> Thanks to anyone who knows of one and cares to share,

  Look at OnSemi, under high performance counters, you'll find ones that 
go 1.4GHz. You will pay for this performance :)
  If a few hundred Mhz is OK, then look at any modern 32 macrocell CPLD
[ Xilinx / Lattice ], and they are closer to $1
-jg

> That's a pretty broad range, Thomas. Like me asking a bank for a loan of
> $1,250 and saying I'll settle for a dollar.
>
> Jerry


Ha. Let me give you a bit of back ground then. I am really pushed for space. 
I need different clock frequencies thru-out my board. My highest frequency 
is a Fox RFXO running around a GHz. I would like to derive all other clocks 
from this one if possible. Next lowest frequency is around 80 MHz. Then a 
few after that. I hate PLLs and I don't want a bunch a xtals on my board. So 
I thought I would just divide down from my highest frequency. One chip 
solution would be the best.

Thomas