Charles could i ask you something,
pervious The value for R and C is found to be 234 and 4.2 nF right. however these components do not exist so therefore the only components I've found is to be 100ohm and 10nF.
calculating the freq response, i get the same freq response as previously obtained. However from the Transfer function the gain was 500 right. but with the new R i found the gain to be 214 by the R2 = R1 * (Currentgain -1) eqn. Is this correct??
pervious The value for R and C is found to be 234 and 4.2 nF right. however these components do not exist so therefore the only components I've found is to be 100ohm and 10nF.
calculating the freq response, i get the same freq response as previously obtained. However from the Transfer function the gain was 500 right. but with the new R i found the gain to be 214 by the R2 = R1 * (Currentgain -1) eqn. Is this correct??
An ideal opamp will make your circuit do what you
want. The input impedance will be extremely low,
(0 ohms in the ideal case) as the (-) input is held to
virtual ground.
The intrinsic input impedance of the op amp will not
figure in the design in this case.
To the extent that the op amp is ideal, the output impedance
will be infinite.
All that remains is selection or design of the opamp and
the choice of resistor values to give you the gain you
want.
You can probably buy your power opamp from Apex and
other sources.
want. The input impedance will be extremely low,
(0 ohms in the ideal case) as the (-) input is held to
virtual ground.
The intrinsic input impedance of the op amp will not
figure in the design in this case.
To the extent that the op amp is ideal, the output impedance
will be infinite.
All that remains is selection or design of the opamp and
the choice of resistor values to give you the gain you
want.
You can probably buy your power opamp from Apex and
other sources.
To anyone out there, Does anyone have a current amplifier schematics??? Doesn't need to follow the 1ohm input and 1 M output. Just need one to firgure how does it work thanks, and erm it would be fab if there was some explaination. thanks guys.
I think you're missing it. The schematic you posted is
a perfectly good current source amplifier.
You seem to be under the impression that you need a
power transconductance amplifier, but you don't.
a perfectly good current source amplifier.
You seem to be under the impression that you need a
power transconductance amplifier, but you don't.
Re: component values
Hi Edo
You are right about getting a current gain of -214 by using a 100 Ohm feedback resistor.
Why don't you try to use 220 Ohms and 15 Ohms in series (i.e. 235 Ohm) ?
The 4.2 nF can also be built by paralleling smaller caps. But be aware that - while it is easy to obtain resistors with tolerances of 1 to 2 % - it is relatively hard to find caps with tolerances of less than 10%.
Regards
Charles
Hi Edo
You are right about getting a current gain of -214 by using a 100 Ohm feedback resistor.
Why don't you try to use 220 Ohms and 15 Ohms in series (i.e. 235 Ohm) ?
The 4.2 nF can also be built by paralleling smaller caps. But be aware that - while it is easy to obtain resistors with tolerances of 1 to 2 % - it is relatively hard to find caps with tolerances of less than 10%.
Regards
Charles
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