Realization of Schmitt Trigger Using Single DXCCII and its Utility as an Adjustable Waveform Generator

Abstract

This paper presents a Schmitt trigger (ST) circuit with anti-clockwise hysteresis and its utility as an adjustable square/triangular wave generator. The ST circuit employs a single dual-X second-generation current conveyor and two resistors. The threshold voltages of the circuit are adjustable such that it can also function as a zero crossing detector. The circuit has a wide operational frequency range and also consumes low power. Without using an additional active block, a square/triangular wave generator circuit is also realized within the same circuit topology. The generator circuit uses a single active element, one grounded resistor and one grounded capacitor only. The use of grounded passive components makes the proposed generator circuit easily integrable. Additionally, the generator circuit is adjustable as its duty cycle is tunable by means of an external current source. The generator circuit also has a wide operational frequency range from 2.1 Hz to 19.2 MHz. The theoretical aspects of the proposed circuits are validated via Cadence simulations. Additionally, a prototype of DXCCII, which is implemented by using current feedback operational amplifier ICs AD844, is used to verify the ST experimentally.