[volt-nuts] Matched resistors

[Charles Steinmetz]

Randy wrote:

>I agree that there are potentially some serious unknown issues with drift
>due to time and temperature due to changes in leakage current, charge
>injection, etc.  I would think some serious characterization would be
>needed before this approach could be used.

I have used LTC1043s in the voltage-multiplier configuration, and 
based on that experience I believe you will find there are too many 
surprises hiding there to reach your error budget.  First, there are 
losses in the conversion -- IME, even when driving nothing but the 
non-inverting input of an LTC1050 chopper-stabilized opamp used as a 
follower, the output voltage of an LTC1043 doubler is quite a bit 
(50uV or more) less than [Vin * 2].  Second, the output of the 1043 + 
buffer is about 100x noisier than the output of the same reference 
followed by a non-inverting gain-of-two LTC1050 (on the order of 
100uVp-p for the 1043 + buffer, about 1uVp-p for the non-inverting 
gain-of-two amplifier in a 10Hz bandwidth, IME).  Also, the 1043 
noise is not symmetrical, so different DC meters may give readings 
that differ by 50uV from one another.

If you try the LTC1043, I'll be interested to see what you find.

Best regards,

Charles