On-chip CMOS position sensors using coherent detection

The migration towards multi-chip integration in microelectronic systems has motivated the use of on-chip sensors for in situ measurement of chip alignment, both at initial assembly and during system operation. This paper presents a CMOS position sensor that measures chip alignment by measuring differences in coupling capacitance. Unlike previous implementations, the present demonstration is immune to transistor leakage current, and can thus operate at high temperatures. A coherent detection scheme further lowers the noise floor, improving accuracy when the chips are far apart.