Pulse Generator Monocycle Gaussian for UWB Applications

This paper focuses on the study and design of a simple MOS generator circuit which provides the first derivative of the Gaussian pulse from input rectangular signal. To generate wavelets required in an ultrawideband (UWB) impulse radio, the first derivative of the Gaussian function is approximated by combining four hyperbolic tangent functions (tanh). Afterwards, four differential pairs are used. The output generator circuit is ultra short monocycle pulses about 244 ps width alternately in phase and in opposition of phase. The generated width pulse can be adjusted by changing the rise and fall time of the input signal. Simulations show that a good approximation of this waveform is possible while using integrated coefficients. A MOS transistor circuit implementation is presented and its simulation results are shown. Comparisons between theoretical and simulation tests are detailed in order to validate the design and the good functioning of the complete structure. . Furthermore, the 2.5 V voltages supply, relative to the chosen MOS 0.35μm technologies (AMS foundry), allows the reduction of the system power consumption. Key words— Transfer function, Hyperbolic tangent, MOS transistors differential pair, Monocycle pulses, Ring oscillator.