A reconfigurable multi-mode direct-conversion transmitter (TX) with integrated frequency synthesizer (FS) is presented. The TX as well as the FS is designed with flexible architecture and frequency plan, which helps to support all the 433/868/915MHz ISM band signals, with the reconfigurable bandwidth from 250kHz to 2MHz. In order to save power and chip area, only one 1.8GHz VCO is adopted to cover the whole frequency range. All the operation modes can be regulated at real time by configuring the integrated register-bank through a SPI interface. Implemented in 180nm CMOS, the FS achieves the frequency coverage of 320-460MHz and 620-920MHz. The lowest phase noise can be -107dBc/Hz at 100kHz offset, and -126dBc/Hz at 1MHz offset. The transmitter features a +10.2dBm peak output power with +9.5dBm 1dB compression point and 250k/500k/1M/2MHz reconfigurable signal bandwidth.