This paper presents a pulse-shaped power amplifier (PSPA) design for delay line based IR-UWB transmitters. By utilizing an array of CMOS transmission gates as a dynamic bias scheme, the switched PA generates desired output pulse with negligible static current. The PSPA designed in 65nm CMOS generates UWB pulses with a 10dB bandwidth of 2.7GHz and a center frequency of 5GHz and achieves reconfigurable pulse shaping with high power efficiency. Simulation results show that the energy consumption of the PA is 3pJ/pulse with a typical current efficiency of 90% at a data rate of 200Mbps.