for reducing the leakage current.
These circuits use nMOS for implementation of a whole gate + one pMOS which is connected between positive supply and nMOS.
NMOS is built with n-type source and drain and a p-type substrate, while PMOS is built with p-type source and drain and a n-type substrate. In a NMOS, carriers are electrons, while in a PMOS, carriers are holes. When a high voltage is applied to the gate, NMOS will conduct, while PMOS will not. Furthermore, when a low voltage is applied in the gate, NMOS will not conduct and PMOS will conduct. NMOS are considered to be faster than PMOS, since the carriers in NMOS, which are electrons, travel twice as fast as holes, which are the carriers in PMOS. But PMOS devices are more immune to noise than NMOS devices. Furthermore, NMOS ICs would be smaller than PMOS ICs (that give the same functionality), since the NMOS can provide one-half of the impedance provided by a PMOS (which has the same geometry and operating conditions).
because pmos has low mobility . the inverter threshold voltage can be shifted to the middle and the inverter is more symmetrical in terms of transistor times.
A rest transistor is either a pMOS or nMOS high VT transistor and is utilized as a change to close off force supplies to parts of a configuration in standby mode. The pMOS rest transistor is utilized to switch VDD supply and henceforth is known as a "header switch."
ULN2802 ULN2803 ULN2804A 8 NPN Darlington transistors, connected in arrays ideal for logic interface level digital circuits (eg TTL, CMOS or PMOS/NMOS) and higher current/voltage such as lamps, solenoids, relays, print Hammers or other similar loads, a wide range of uses: computer, industrial and consumer applications. All device functions are transiently suppressed by collector output and clamping diodes. The ULN2803 is designed for standard TTL compliance, while the ULN2804 is manufactured to fit 6 to 15V on high-level CMOS or PMOS. The circuit is a reverse output type, that is when a low-level voltage is an input, the output terminal can be turned on to work. For more, The ULN2803 and ULN2804 have the same pinout and current parameters. But there is a little difference. The drive voltage of ULN2803 is 5V for TTL and CMOS circuits. The driving voltage of ULN2804 is 6V-15V for CMOS and PMOS circuits. Reference: The Overview of ULN2804A [FAQ] [ utmel]
PMOS - (drain + source) = p-type doping NMOS - (drain + source) = n-type doping :)
yes
it becomes a buffer
true
we try to reverse bias not the channel and substrate but we try to maintain the source,drain junctions reversed biased with respect to the substrate so that we dont loose our current in the substrate.
It will act like a buffer but not the exact buffer. Since nmos conduct logic 1 weakly and pmos conduct logic 0 weakly, the output ranges from vdd-vtn to vtp. For eg. If you apply 5v then the op will be 4.3 not the complete 5v. If you apply 0v then output will be 0.7v not 0 v. Hope this works
Due to differences in carrier mobility between P and N type semiconductor, for similarly doped channels the channel of a PMOS FET will be a bit wider than the channel of an NMOS FET so that they both have identical channel resistance. To make the channel wider the PMOS FET will take a larger chip area.