IMPLEMENTATION OF SWITCH DEBOUNCE CIRCUIT USING GDI BASED SCHMITT TRIGGER

Abstract

Switch bouncing causes multiple unwanted transitions in digital circuits when me- chanical switches are pressed or released. In this work, a switch debounce circuit is implemented using a Schmitt Trigger designed with GDI-based NAND gates. The Gate Diffusion Input (GDI) technique reduces power consumption, delay, and area by minimizing transistor count compared to CMOS. The Schmitt Trigger introduces hysteresis with threshold voltages of 0.7V and 0.16V, effectively filtering bounce noise. Simulations in LTspice confirm stable output and lower power usage. This design offers an efficient, low-power hardware solution for switch debouncing in portable and embedded systems. When a mechanical switch is pressed or released, it doesn’t settle instantly; instead, it tends to bounce, creating a series of rapid, unintended on-off transitions. These glitches can lead to unexpected behavior in digital circuits if not handled properly. To address this issue, a switch debounce circuit has been developed in this work, incorporating a Schmitt Trigger that is built using GDI-based NAND gates. The Gate Diffusion Input (GDI) technique stands out by offering a significant reduction in power consumption, propagation delay, and silicon area, mainly due to its reduced transistor count when compared to conventional CMOS designs. The use of a Schmitt Trigger is particularly beneficial here, as it adds hysteresis to the system—meaning the circuit reacts differently depending on whether the in- put is rising or falling. This characteristic, with defined threshold voltages of 0.7V for the high transition and 0.16V for the low, helps to cleanly filter out the noise caused by switch bouncing, ensuring that only legitimate transitions are passed to the output. Simulations conducted in LTspice further validate the design, showing that the output remains stable and consistent, even under noisy conditions, while consuming less power. Overall, this design presents a practical and efficient hardware solution for han- dling switch bounce, making it highly suitable for power-sensitive applications such as portable devices and embedded systems where reliability and performance are critical.