This paper describes a monolithic tunable active time delay with variable gain, designed using monolithic-microwave integrated-circuit (MMIC) technology, targeting in 3.5-4.5 GHz range with a low power consumption of 9.4 mW. It is impossible to realize such great delays with ideal transmission line in MMIC, because of the length required for the line. In this paper We present analytical and computer-simulated results using 0.35 mum SiGe BiCMOS process for a tunable active time delay in 3.5-4.5 GHz range. It works as a pure time delay over 800 MHz frequency band.