Using the schematic shown, when I apply a 1 amp test current to the non-inverting input of OP1 and solve for the voltage at that terminal, I don't get a conductance of (Y2 Y4 Y6)/Y3 Y5; my result involves Y0 and Y1, which surely must be true. Is the expression you give for Yin1 for a simpler circuit than shown in this post? I also get a different result for Yin2 for the circuit shown here.

No - there is a misunderstanding on your side.
In post#16 I wrote: "From known (basic) GIC chatacteristics, the input conductances at both non-inv. input nodes for OP1 and OP2 are....".
The well-known GIC-topology (introduced by Antoniou) consists of two opamps and five external impedances (resp. conductances), one of them grounded.
That means: The passive part(s) which are connected to the inv. input opamp node under consideration are, of course, NOT part of the corresponding input impedance/conductance.
This should be clear also because these external elements are part of the described voltage divider circuits - resulting in the voltages at the opamp input nodes Vp(1) and Vp(2), respectively (see my post #16).

(I hope my correction - change of "transconductance" into "connductance" - now was succesfull)

 

Imagine that this problem was given as homework to someone who did not know about GIC's (I suspect the TS probably does not). How would you find the transfer function without reference to already known properties of GIC's?

 

Imagine that this problem was given as homework to someone who did not know about GIC's (I suspect the TS probably does not). How would you find the transfer function without reference to already known properties of GIC's?

In this case, the student must, of course, derive the input impedance of the GIC block by himself (not very involved).
For my opinion, this approach would be much better than to start with basic Kirchhoff equations for the complete circuit.
It is always better (and easier) to split such an involved task into several separate parts:
(a) Superposition of two processes
(b) GIC input conductances
(c) Corresponding voltage division (external elements)
(d) GIC input voltages
(e) Corresponding output voltages
(f) Superposition of both results

PS: May I ask you, what is your approach? How would YOU find the transfer function?

 

In this case, the student must, of course, derive the input impedance of the GIC block by himself (not very involved).
For my opinion, this approach would be much better than to start with basic Kirchhoff equations for the complete circuit.
It is always better (and easier) to split such an involved task into several separate parts:
(a) Superposition of two processes
(b) GIC input conductances
(c) Corresponding voltage division (external elements)
(d) GIC input voltages
(e) Corresponding output voltages
(f) Superposition of both results

PS: May I ask you, what is your approach? How would YOU find the transfer function?

If the student didn't know there is such a thing as a GIC block, how would he realize that there was a GIC block contained within his overall schematic?

I would use ordinary nodal analysis. First number some nodes in the schematic:


Then solve the 3 nodal equations and 2 constraint equations:

 

I would use ordinary nodal analysis.

OK - of course, a software supported analysis is the quickest method.
I also could use a computer program for a symbolic circuit analysis - however, I think that was not the background of the question.

 

OK - of course, a software supported analysis is the quickest method.
I also could use a computer program for a symbolic circuit analysis - however, I think that was not the background of the question.

To me the issue is not whether one uses software supported analysis. The issue is what method should the student use if he doesn't know about GIC blocks? How would you do it without referring to GIC blocks?

 

I am sorry, I came here to get assistance. If I knew how to easily solve the network using nodal analysis, I would not have asked for help. My project involves medicine, and so does my degree. Immunology is my speciality, not electrical engineering, which is why I came here for assistance.

If it is very simple, would you please mind assisting me? I tried my best and showed my work.

Hello there,

Well maybe you could check out how to do Nodal Analysis it's not really hard to do.
You basically sum the currents into a node and the algebraic sum must equal zero. You end up with a number of equations that you then solve simultaneously. There is a matrix method that handles this too which is very general so works for many types of circuits.

Of course there is a little more to it then that. For one, you should use complex numbers to handle the capacitor impedances. You can also use a voltage controlled voltage source fo the op amps to make it easier and make the gains rise toward infinity to get a theoretical result, ot make the gains very high like 100000.

In the complex world a resistor has value (R,0) or R+j*0 while a capacitor has value 0-j/C where j is the complex operator. So if you had a resistor R1 in series with a capacitor C1 the total impedance would be R+j*0 plus 0-j/C which equals R-j/C. So some of this is very simple.
If you never worked with complex numbers you will not get much out of any analysis because it will have to be very very specific to this particular circuit and so you will not know how to do the next circuit you encounter.

To learn Nodal Analysis it is best to start with resistors and voltage and maybe current sources. You can then apply that to circuits that contain capacitors and inductors by using complex numbers.
You might also learn about dependent sources as they can be used to mimic a wide variety of devices.

We could go over a simple example if you like. The attachment shows the basic idea behind Nodal Analysis. Here we are writing the equation for the node vN. Since the current through any resistor is the difference in voltages at the terminals divided by the resistance, we know the current through each resistor and thus we can sum the three currents to zero.

 

To me the issue is not whether one uses software supported analysis. The issue is what method should the student use if he doesn't know about GIC blocks? How would you do it without referring to GIC blocks?

As mentioned already in my post#23 - the student must, of course, derive the input impedance of the GIC block by himself (not very involved). In this case, it is not necessary to know the term "GIC". However, some basic knowledge about ideal opamps is required. When assuming all input nodes at the same potential it is not very complicated to calculate the input impedances.
More than that, when I see a system where one common signal source drives two different pathes into such a circuit I immediately think of superposition as the best method.