Gaussian pulse Generators for subbanded ultra-wideband transmitters

This paper presents calculations for approximating the measured spectrum of pulsed signals in the high and low pulse-repetition-frequency (PRF) region. Experimentally verified peak and average power calculations are presented for pulse trains with no modulation and when modulated by random data using binary phase-shift keying (BPSK). A pulse generator is presented that is built using commercially available discrete components. BPSK pulses are generated at a PRF of 50 MHz. The output spectrum has a center frequency of 5.355 GHz and a -10-dB bandwidth of 550 MHz. A technique for pulse shaping is presented that approximates a Gaussian pulse by exploiting the exponential behavior of a bipolar junction transistor. This technique is demonstrated by a pulse generator fabricated in a 0.18-μm SiGe BiCMOS process. BPSK pulses are generated by inverting a local oscillator signal as opposed to the reference pulse, improving matching. Pulses are transmitted at a PRF of 100 MHz and centered in 528-MHz-wide channels equally spaced within the 3.1-10.6-GHz ultra-wideband band. Measurement results for both transmitters match well with calculated values.