[time-nuts] V standards

[Bruce Griffiths]

Richard Moore wrote:
> Brooke, I read the patent with interest, and I cannot see how using  
> the LM399 and AD587 together represents an improvement over just  
> using a 399 and a chopper amp for the needed gain to get 10V (or  
> whatever) out. Geller's external adjustment R chain will suffer  
> tempco problems similar to a set of Rs used to gain-set the chopper,  
> and making the chopper an integrator with a long TC should help with  
> the 399's noise. 
You need a low pass filter with a well defined dc gain not an integrator.
You can also average the outputs of several 399s to reduce the noise.
However this requires a lot of 399s if one wants to reduce the noise by
a large factor.
The LTZ1000 is significantly quieter than an LM399.
Its significantly cheaper to use a single LTZ1000 than an array of 399s
with the same noise (using the same low pas filter).
> Can anyone see where a further tempco improvement  
> from using the AD587might come from?
>
> Dick Moore
>
>   
Bruce