Pass Transistor Circuit. To better understand this distinction let s first discuss an important conceptual detail what do we really mean by logic high and logic low. R2 and r3 are used to set up the bias point for the base of the transistor.
The operating conditions for the transistor are set up in the normal way. This is in contrast to the typical cmos approach whereby an output node is always driven to logic low or logic high via the low resistance path provided by a pmos or nmos transistor. In electronics pass transistor logic describes several logic families used in the design of integrated circuits.
This provides a simple form of feedback system to ensure the zener voltage is maintained at the output albeit with a voltage reduction equal to the base emitter junction voltage 0 6 volts for a silicon transistor.
To better understand this distinction let s first discuss an important conceptual detail what do we really mean by logic high and logic low. Pass transistor logic. The circuit uses a single pass transistor in the form of an emitter follower configuration and a single zener diode or other voltage regulator diode driven by a resistor from the unregulated supply. For the circuit shown in figure 5 2 5v 2 5v vout 1 a calculate the voltages at node voutl and vout2 given that threshold voltage 2 0v of each transistor is 0 3v.
