First of all, this isn't really homework, I'm studying for an exam, but I figured this is the most suitable place for such a question. Anyway, please find the circuit in the attachment.

Now, here is the data: I_0 = 100uA, R1=R2=R3=10kOhm, R4=90kOhm, V_T=0.7 V, B=u_n*Cox*W/L=2 mA/V^2, Vdd=-Vss=1.65 V, and no Early effect is present.

Ok, my questions are:

1. Set the + and - (don't know the word for this, are they pins?) for the OpAmp so that there is negative feedback in the circuit.

2. If the OpAmp has a voltage gain of a1=1000, find the voltage gain of the whole circuit, a = v_i / v_u (near the Bias point of course )

The problem I have is that when I draw the small-signal model, I get the voltage gain as: a=-10*gm1/gm2, where gm1, and gm2 are the transistor permitivities (don't know how these are called in english too ), calculated with gm1 = sqrt(2*B*I_1), where I_1 is the DC current near the bias point of transistor 1.

I could say that the main problem I have is calculating the currents I_1 and I_2 near the Bias Point. I said that the + sign is down and the - sign of the OpAmp is above it on the picture, is that correct?

Now, here is the data: I_0 = 100uA, R1=R2=R3=10kOhm, R4=90kOhm, V_T=0.7 V, B=u_n*Cox*W/L=2 mA/V^2, Vdd=-Vss=1.65 V, and no Early effect is present.

Ok, my questions are:

1. Set the + and - (don't know the word for this, are they pins?) for the OpAmp so that there is negative feedback in the circuit.

2. If the OpAmp has a voltage gain of a1=1000, find the voltage gain of the whole circuit, a = v_i / v_u (near the Bias point of course )

The problem I have is that when I draw the small-signal model, I get the voltage gain as: a=-10*gm1/gm2, where gm1, and gm2 are the transistor permitivities (don't know how these are called in english too ), calculated with gm1 = sqrt(2*B*I_1), where I_1 is the DC current near the bias point of transistor 1.

I could say that the main problem I have is calculating the currents I_1 and I_2 near the Bias Point. I said that the + sign is down and the - sign of the OpAmp is above it on the picture, is that correct?