An all-digital field programmable gate array based electromagnetic subtraction technique for direct UWB pulse generation is presented. Using this technique, it is possible to generate Gaussian pulses, monocycles or doublets with high flexibility using a single printed circuit board layout. User-controlled parameters include amplitude, pulsewidth, pulse-type, repetition rate or even modulation. Measurements indicate a Gaussian pulse with 1.24 V peak amplitude and a 10% pulse-width of 670 ps can be transmitted at a repetition frequency of 100 MHz. The corresponding − 10 dB bandwidth is 2.8 GHz.Introduction: Over the past decade, UWB radio has been commonly proposed for short-range high data rate communications [1] or for radar applications in the industrial [2] and medical fields. However, widespread implementation is still ongoing. This Letter contributes to providing an easy implementable development platform for UWB signal generation with higher flexibility compared with other transmitters. The key innovation of the Letter is the usage of a field programmable gate array (FPGA) together with an electromagnetic (EM) subtraction technique to form different Gaussian pulse shapes in a direct way. Two general transmitter implementations exist to date. CMOS integrated circuits can be considered for full-custom designs, while on the other hand, transmitters can be composed using commercial off-the-shelf components. The latter are implemented with step recovery diodes (SRDs) [2] or mesfets to generate steep edges and provide flexibility to some extent. An all-digital FPGA based implementation combines the high flexibility of CMOS designs together with rapid and easy implementation.

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A novel highly flexible mixer-based ultra-wideband (UWB) pulse generator is designed. The baseband pulse generator has a controllable pulse width between 200 ps and 8 ns, while the output amplitude only varies over 80 mV in this entire range. The mixer is adjustable so that the voltage controlled oscillator leakage can be controlled and minimised. The proposed architecture gives a highly flexible UWB pulse generator for which the characteristics can be adjusted to fit the specifications of different applications and the spectral mask of the country/region of usage.

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