This paper presents an ultra-low-power pulse generator based on a dedicated design of a voltage controlled ring oscillator (VCRO), buffer and pulse shaping filter. A control voltage can be used to control the pulse repetition frequency. The design was made using 65nm CMOS technology. The pulse generator produces a pulse having 0.4ns width and 470mV peak-to-peak amplitude. The -10dB bandwidth is 4.6 GHz from 2.4 to 7GHz. The energy consumption is 1.2 pJ per pulse while the emitted energy is 75% of the total energy consumed per pulse. This is the minimum emitted energy per pulse that the pulse generator can transmit in order to be detected by the receiver for short range indoor applications.