A CMOS ultra wideband (UWB) pulse generator with low energy dissipation and high peak amplitude is presented for 6-10 GHz applications. The pulse generator comp lies with the FCC spectral mask for indoor UWB systems. It consists of a glitch generator, a pulsed oscillator, and a pulse shaping filter. The pulsed oscillator is switched on by the glitch signal only for a short duration, so as to make a UWB pulse. For sub-nanosecond pulse generation, a pulsed oscillator with fast transient response is proposed. A pulse shaping filter makes the oscillator output fall into the FCC spectral mask. The pulse generator is fabricated using a. 0.18 mu m CMOS process. The core chip has a size of 0.11 mm(2). It shows pulse duration of about 500 ps with -10 dB band-width of 4.5 GHz from 5.9 to 10.4 GHz. The energy consumption is 27.6 pJ per pulse with a peak-to-peak amplitude of 673 mV on a 50 Omega output load. The generated pulses are very coherent with 1.8 ps RMS jitter.