Current Mirror Sense Amplifier
Current mirror is the circuit which tries to drive same current at the output as in the input. Here, DOUT is connected to the gate terminals of both the PMOS transistor P1 &amp; P2 and it turns ON the transistors (because DOUT=0). Current flowing in P2 is same as current flowing in P1 (I1=I2) if the W/L ratio's of both the transistor are same. If W/L ratio of transistor P2 is α times the W/L ratio of P1, then I2=αI1. And we will get the amplified output current at the DOUT_B.