Pulse delay techniques for PPM impulse radio transmitters

A great challenge in impulse radio pulse position modulation (PPM) is a simple time delay control for the modulated pulses. Two transmitter prototypes for UWB pulse generation will be presented. The first is a step recovery diode (SRD) based pulser, where the time position of the pulse is controlled by a variable current source. The second circuit shifts the pulse in time by varying the operating point of an avalanche transistor. The shape of the pulse equals higher derivatives of the Gaussian pulse for both circuits in assistance with a high pass filter.