Hi Guys,
I've got a circuit in SPICE i cannot, for the life of me, make work how i intend. It is supposed to be a current source. It is currently set up with a dummy load (D)
So the general idea here is U2 acts as the current source. U3 is a transimpedance amp outputting a voltage = R1*Iout(u2). U4 is a non inverting summing amplifier, which sums the output of the transimpedance amp with a setpoint (Vset+(R1*Iout[u2])). This sum is then fed into the noninverting input of U2. U2 should then attempt to hold the non inverting input at GND (inverting input) by varying its output. This should close the feedback loop.
This is how it works in my head. But ltspice just shows oscillation (even when using ideal op amps). Can somebody point out what I've done wrong.
Thanks
I've got a circuit in SPICE i cannot, for the life of me, make work how i intend. It is supposed to be a current source. It is currently set up with a dummy load (D)
So the general idea here is U2 acts as the current source. U3 is a transimpedance amp outputting a voltage = R1*Iout(u2). U4 is a non inverting summing amplifier, which sums the output of the transimpedance amp with a setpoint (Vset+(R1*Iout[u2])). This sum is then fed into the noninverting input of U2. U2 should then attempt to hold the non inverting input at GND (inverting input) by varying its output. This should close the feedback loop.
This is how it works in my head. But ltspice just shows oscillation (even when using ideal op amps). Can somebody point out what I've done wrong.
Thanks
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