This Project Report On Schmitt Trigger presents a Schmitt trigger. Schmitt trigger is a wave shaping circuit used for generation of a square wave from a sine wave input .It is a bi stable circuit in which two transistor switches are connected regenerative. If the two transistors are Q1 and Q2 ,when Q1 is ON then Q2 is OFF or when Q2 is ON then Q1 is at OFF position.
Schmitt trigger consists of two identical transistors Q1 and Q2 coupled through an emitter resistor Re. Resistors R1 and Rb2 form a voltage divider across vc1 and ground. This provides a small forward bias to the base –emitter junction of transistor Q2. When the supply is switched ON, with no input signal, transistor Q2 starts conducting. The rise in current (Ie) of Q2causes a voltsge drop across Re ,i.e. Vre = IeRe. This voltage provides a reverse bias across the emitter-base junction of Q1 and it is driven into cut-off state. Since Q1 is in OFF state, the voltage at its collector rises to Vcc since the collector of Q1 is coupled to base of Q2 through the resistor R1, the forward bias for the transistor Q2 is increased. Thus Q2 is driven into saturation.
1. Schmitt trigger is used for wave shaping circuits.
2. It can be used for generation of a rectangular wave form with sharp edges from a sine wave or any other wave forms.
3. It can be used as a voltage comparator.
4. Schmitt trigger is used as amplitude comparator. It identifies the moment at which any arbitrary waveform attains a particular reference level.
Project Report On Schmitt Trigger Conclusion:
A new Schmitt trigger circuit, which is implemented by low-voltage devices to receive the high-voltage input signals without gate-oxide reliability problem, is proposed. The new proposed circuit, which can operated in a 3.3-V signal environment without suffering high-voltage gate-oxide overstress, been fabricated in a 0.13-μm 1/2.5-V 1P8M CMOS process. The experimental results have confirmed that the measured transition threshold voltages of the new proposed Schmitt trigger circuit are about 1 and 2.5 V, respectively. The new proposed Schmitt trigger circuit is suitable for mixed-voltage input-output interfaces to receive input signals and reject input noise.
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