Option structure in a combo type memory device

摘要

PURPOSE: An option structure of a combo type memory device is provided to realize three metal options with only one mask without fabricating an additional mask by replacing a metal option with an electric circuit to discriminate a device. CONSTITUTION: According to the control circuit, each of the first and the second and the third option is constituted with the first and the second and the third transmission gate(T1,T2,T3) respectively. The first transmission gate operates according to the first control signal(sdr25) and the inverted first control signal, and the second transmission gate operates according to the second control signal(sdr33) and the inverted second control signal, and the third transmission gate operates according to the third control signal(ddr) and the inverted third control signal.