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The application of resonant tunneling diodes generated pulses with very fast rise and fall times. In both (RTD) for generation of gaussian-like monocycles and modified publications, the generation was based on electrical hermite pulses of 2nd order for ultrawideband (UWB) impulse stimulations ofthe RTD and the pulses were depending on the radio is investigated in this paper. A circuit concept employing a clock period. pin-photodiode and two RTD based monostable bistable threshold logic elements (MOBILE) is introduced. The circuit To overcome the direct dependence of the pulse repetition generates, depending on a digital optical input signal, arbitrary Te on the dignad,the puse repe pulse cycles at the output of the circuit. Based on the rate onthe clock signal, theRTDs are setup using aMOBILE measurement result of a single MOBILE, simulations are configuration in connection with a controlling current source presented that show the capability of the proposed circuit to [4] to generate the pulses. generate pulses like single gaussian pulses, gaussian monocycles, The controlling current source is used to modulate the output and 2n -order modified hermite pulses. Experimental pulse by switching them 'onv and 'off in the time domain. A verification of positive and negative gaussian pulses with a width meased outputwem [6] is pent in this workithA of 100 ps is demonstrated for a pulse repetition rate of 13.2 measured output waveform [6] Is presented in this work that Gpulses/s. demonstrates the capability of MOBILE for the generation of Index Terms -resonant tunneling diode, pulse generator, fast gaussian-like signals. gaussian monocycles, modified hermite pulses, impulse radio.Furthermore, by introducing a differential approach with two MOBILE gates, the simultaneous generation of two gaussianlike impulses with different polarities will be demonstrated. If I. INTRODUCTION combined, these two output pulses form a gaussian Impulse based short range communication (Impulse-monocycle or higher order hermit-like pulses. The following Ultrawideband) and imaging applications need specific pulse chapters will briefly discuss the generation of such an output waveforms that satisfy certain spectral requirements [1]. waveform and experimental verification of the gaussian Usually CMOS based triangular pulse generators are used impulse will be shown. together with a pulse forming network to realize pulse signals [9]. Another approach is to take advantage of the exponential II. MOBILE PRINCIPLE current-voltage characteristic of bipolar transistors to generate fast pulses [8]. Both approaches offer fast pulse repetition A MOBILE circuit consists of two RTDs with different rates but always require a complex pulse-forming network. device areas Adriver and Aload connected in series. The area In this paper a different approach for generating pulses is difference results in a peak current difference Alpeak between proposed. Yan et. al [7] have described the non-linear current-the load and driver diode and defines the required threshold...

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