On pp. 103 and 105 of "The Art of Electronics Student Handbook" (see attached pdf), it talks about the current mirror circuit. I am very confused about how this circuit works. First of all, I cannot see where the input signal is fed into the circuit--it looks like it is just in a steady state. On p. 105, it challenges the reader to explain how the "program side" of the current mirror works. I would guess that the voltage at the base must be 0.6V, because the base is always 0.6V higher than the voltage of the emitter, which in this case is grounded. Then, because base is connected to the collector, the collector must be at 0.6V also, which means that I_C should be about 1 mA. If we use I_C=\beta * I_B (and assume that \beta=100), then that means that I_B should be 0.01 mA. However, this understanding of the circuit includes nothing about negative feedback. What am I missing?