In this paper, a low-cost CMOS ultra-wideband (UWB) impulse transmitter module with a compact form factor is proposed for impulse-radio communications. The module consists of a CMOS impulse generator, a compact bandpass filter (BPF), and a printed planar UWB antenna. The impulse generator is designed using a Samsung 0.35-mu m CMOS process for low-cost and low-power fabrication. The measurement shows the fabricated chip makes a train of sharp triangular pulses with a peak voltage of about 2.8 V under the supply voltage of 3.3 V. To make an impulse fit the Federal Communications Commission (FCC) spectrum mask, the compact BPF is developed using a coupled strip line and a tapered stub. Also, the compact planar UWB antenna is developed. All of the components of the UWB transmitter module are fabricated on a single package using system-on-package technology for miniaturization. The proposed UWB transmitter is tested in an office environment. The measured results show that the generated UWB signal meets the FCC regulation, and the peak-to-peak amplitude of received UWB signal at I-m distance on line of sight is 16 mV(pp) with a 10-dB-gain low-noise amplifier in the receiver.