i A PHYSICAL IMPLEMENTATION WITH CUSTOM LOW POWER ...

the input signal D transitions, node Q~ begins to discharge with current Ictrl. Once the voltage at
node Q~ drops below the threshold voltage of the PMOS transistor M3, the transistor M3 turns
on and begins to charge node Q. Once node Q has charged to the threshold voltage of the NMOS
transistor M2, the transistor turns on and discharges node Q~ faster. The transistors M3 and M2
now form a positive feedback which makes the switching action faster. As the delay in the
positive feedback action is small, the total delay is dominated by the delay due to discharge of
Q~ using the discharge current Ictrl and the charging of Q. The signal integrity of the thyristor
based delay element is good because of the positive feedback action which causes the output
edges to be sharp [16].
Figure 6-13: CMOS Thyristor structure
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