This paper presents a direct conversion transmitter implemented in 0.13um SiGe BiCMOS integrated circuit (IC), targeting Ka-band satellite communications. The IC is comprised of an active IQ baseband filter with adjustable cutoff frequency 90-720MHz, IQ up-converter with gain control and local oscillator (LO) leakage compensation, LO generation network, variable gain power amplifier and auxiliary blocks. The chip uses 8-11GHz external LO and delivers 14dBm saturated output power (Psat) in the frequency range 26-31GHz, with a gain control dynamic range of 54dB and 15dB full gain. The occupied silicon area is 4 mm^2 and the power consumption 547mW from 2.6V.