What is the function of the cross connection of the five tubes in the middle of this comparator?

真让人头大55

What is the function of the cross-connected five tubes in the middle of this comparator? The simulation test shows that it is a falling edge trigger. Specifically, where does the falling edge trigger play a role?

It would be best if you could analyze the entire picture in full, thank you! (The 5 above are p18, the others are n18)

埋土书生

This circuit is a differential input and differential output circuit.

1. clkc should belong to the enable terminal. The low level enable is effective (the falling edge statement is inaccurate), which controls the power-on and output blocking of the main body of the circuit. When the level is high, the differential end outputs are all high, the differential input pole is not connected to VDD, and the main body of the circuit does not work. When the level is low, the top CMOS is turned on, the differential input pole is connected to the power supply, the left and right CMOSs below are turned off, the output signal blockade is released, and the remaining main part of the circuit starts to work normally.

2. The differential input pole formed by the two cross-connected tubes in the middle and the two tubes on the upper side is the main part of the circuit. The two cross-connected tubes play the role of positive feedback. There is no need to explain the role of adding positive feedback in comparator applications. You can first regard the two tubes on the lower side as two resistors, and then look at the main body of the circuit as a differential amplifier. By introducing the cross-connected coms, the output level of one side is given to the coms gate on the other side, so that the output level of the other side changes quickly to the opposite state, forming a cross positive feedback.

3. In addition, this circuit should be a logic circuit, used in differential communication circuits, such as 485 transceivers, of course, it can also be said to be a comparator