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Jim Thompson

On Mon, 02 Jul 2007 09:56:01 +0100, Tony Williams
wrote:

In article ,
Jim Thompson wrote:

It's an amplifier with less than 10KHz bandwidth (to get quick
settling), gain of 300, but it's essentially a DC signal.

Depends if you are the customer or supplier. If you
are the supplier then you want the widest barn door.

Assume Gain = K = dVout/dVin, measured over the
widest possible swing of Vout, dVoutmax/dVinmax.

"0.25% linearity" is the departure from the straight
line as a percentage of Voutmax... = Voutmax/400.

"DC-offset" is the value of Vout when Vin=0 for the
particular device under test.

Vout = K*Vin +/- (Voutmax/400) +/- (DC-offset).

So to verify any particular DUT.

Measure and record DC-offset and K for that device.

Then measure Vout for a range of Vin = 0 to Voutmax/K.

If the DUT is in spec, then for all plotted values of Vin:-

(Vout - K*Vin -/+ DC-offset) = +/- Voutmax/400

What I'm doing, though I'm sure it over states the error is...

(V(OUTP,OUTN)-(MAX(V(OUTP,OUTN))-MIN(V(OUTP,OUTN)))/6m*V_VSW)

in PSpice Probe, since I have 65 process corners to test :-(

(6mV is the input sweep, V_VSW is the name of the source)

The gives the classic error "S-curve" _except_ the end point are at
zero instead of the usual even spread about zero error.

Since I have 65 sets to do I'm trying to avoid best-fit for each :-(

...Jim Thompson
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