This image is taken from the book Electronic circuits by Donald A. Neamen.

I am facing problem in understanding it's concept so I have new questions here.

1.Will current flow in the circuit from positive Vcc to negative Vcc even when the inputs Vb1 and Vb2 are open circuits?


2.There is a constant current source at the tail of this circuit and as far as I know is that an independent current source provide the constant current in the circuit regardless of the other components in the circuit so will the current remain constant in this circuit no matters what the values of positive Vcc, negative Vcc, inputs Vb1 and Vb1?

3.If input Vb1 is greater than Vb2 then bjt Q1 will draw more current and Q2 will draw less current? Is this because the constant current coming from the constant current source will go more towards Q1 because it's base current is now more than the bjt Q2 but the overall current in the circuit will remain constant?

 

Before answering your questions, please realize this is mot a practical circuit, it is a skeleton, using biassing voltage sources and current siurces where tgere would be actual components in a teal circuit.

1. Yes, there are biasing voltages on the based which turn the transistors partially on.

2. No, there is no such thing, it is a theoretical concept. A practical circuit will have limitations.

3. Yes, that is how a differential amp works, the two transistors split the current according to the difference between the two inputs.