This is a monolithic integrated circuit that contains three PIN diodes connected to form a pi-greek circuit. It is used as variable attenuator in HF - VHF - UHF up to 1.5 GHz bands, the attenuation range is from 1.5 to about 45 dB (depending on the frequency). It is driven by a common transistor like BC107 or BC258 or other similar, it can be used as RF attenuator or fast AGC circuit in receivers IF, etc... it is pin-compatible and similar to TDA 1053.