Analog Linearization
Analog Linearization
(OP)
A couple of months ago, some guy with his own company approached my company with a circuit that consisted (he said) of 7 components (one op-amp, resistors and caps) that could improve linearization. We never got to see the circuit (He believed he could get rich on this...my company didn't bite). While we never had a black box from him, his simulations did show a large improvement in linearization. Normally we use a log amp that or just L/C matching (this is eddy-current sensing)to get some linearity, but depending on range/offset, we may end up with up to 10% non-linearity. Would anyone have any idea as to how he was configuring this circuit to linearize? Again, it was a single active component, an op-amp, with several passive components.
Thanks....Steve
Thanks....Steve





RE: Analog Linearization
Or did you mean that the whole circuit responded less non-linearly than another whole circuit?
RE: Analog Linearization
and the desired specs, I will see what I can do...
<nbucska@pcperipherals.com>
RE: Analog Linearization
The only other clue I have is from plotting the non-linearity versus distance. Normal curve shape is the classic 'S' curve. After his circuit, that 'S' curved looked like it had been full-wave rectified--two humps with a notch about mid-range.
Now that my company is not going to buy his idea, I was just wondering if he really discovered something wonderful.
didymus7
RE: Analog Linearization
It is debatable whether or not an ordinary silicon diode is an active component. Certainly a Tunnel diode and a Gunn diode would be considered active as they have transient power gain. But a 1N4148? I’m not so sure.
S-correction curves are done on TV scan linearisation circuits and consist of magnetically biased inductors. You can also get voltage dependant resistors. Rectification is another matter though.
RE: Analog Linearization
These two humps are riding on top of what should be a straight line for the gain curve?
A zero-crossing notch is usually a really bad thing for amplifiers, since it introduces tons of distortion, particularly at low signal levels.
TTFN
RE: Analog Linearization
didymus7
RE: Analog Linearization
1. To use a A/D with the output going to an eprom/eeprom (with the linearization table) output to a D/A (also needs a clock circuit)
2. Analog input to a single chip micro with Anaog in, programmed with linearization table, PWM output with R/C network to obtain a voltage signal.
3. A variation of No. 2 above is to use a V/F circuit to convert the signal to a digital form and use a micro without analog input.
All three of these are in used with some smart(?) sensors.
RE: Analog Linearization
John
RE: Analog Linearization
And Rich2001, we do have different models that incorporate all of what you have mentioned. I'm looking for an 'oddball' solution....
didymus7
RE: Analog Linearization
OA+R-s then it must be biased close to input limit or
current feedback amplifier or some similar non-standard OP-AMP.
<nbucska@pcperipherals.com>