High isolation analog 4×4 matrix switch LSI for centralized control microcell radio systems

Centralized control microcell radio systems use analog matrix switches to flexibly switch the modulated spectrum signals to each base station burst by burst. This allows personal stations to be tracked as they move between microcells so handover is seamless. The paper describes a newly developed high isolation analog matrix switch LSI for a centralized control microcell radio system. This switch uses cascade connections between input signal divider switches and output signal combiner switches to realize high on-off ratios. To minimize signal leakage, low-impedance output circuits, differential signal lines, and two package-leads per input port are employed in the inside of the LSI. Moreover, the matrix switch LSI has the emitter open type output buffer circuit configuration to minimize current leakage through the LSI substrate between the output transistors. The isolation value is better than -70 dB at frequencies under 40 MHz