02-AND Gate -using transistor

And Gate Using 2 Transistor: ------------------------------------ The use of transistors for the construction of logic gates depends upon their utility as fast switches. When the base-emitter diode is turned on enough to be driven into saturation, the collector voltage with respect to the emitter may be near zero and can be used to construct gates for the TTL logic family. For the AND logic, the transistors are in series and both transistors must be in the conducting state to drive the output high