| 摘要 |
PURPOSE:To reduce the chip area by providing control-signal-line layers on divided-voltage leads of a voltage divider comprising diffused resistors or capacitors, with the cross points of the leads and the signal lines being switches of an MOS structure, wherein the switches that are opened and closed by the control signal are made of an E (enhancement) MOS and the switches that are held ON are made of a D (depression) MOS. CONSTITUTION:Diffused-resistor layers R2 to R4 which are formed on a semiconductor substrate have lengths of l2 to l4 and resistances r2 to r4. Switches T are formed at the cross points of the resistors and signal lines S1 and inverted S1 which give alternatingly inverted control signals each other. The signal line and the MOS gate for switching are made of poly Si. The cross points of the diffused layer extended from the contact point of the resistor layers R1 and R2 and the signal lines S1 and inverted S1 are made of E-type MOS E11 and D-type MOS D11, respectively. The cross points of the diffused layers extended from the contact point of resistor layers R2 and R3 and the signal lines S1 and inverted S1 are made of MOS D12 and MOS E12, respectively. Thereafter, the succeeding cross points are formed in the same way. When ''H'' is applied to the signal line S1, and ''L'' is applied to the inverted S1, contact voltages of the resistor layers appear at terminals P1 and P2 respectively. In this constitution, the control lines can be overlapped on the diffused layers, whereby the chip area can be reduced. |
