| 摘要 |
1474999 Volume control SONY CORP 17 July 1974 [23 July 1973] 31691/74 Heading H4R [Also in Division H1] A volume control circuit comprises a plurality of IGFETs, SRG1-SRGn, having sensitive gates whose ends are A.C. coupled to the source and drain respectively, and different transconductances, the signal to be controlled being connected across the sources and drains which are connected in parallel, and a control signal V G being connected across the gates and sources such that all the gate-source voltages are different. The different trans-conductances may be achieved by varying the widths of the channel regions. The FETs are formed in an integrated circuit in a silicon substrate which is form-doped, has silicon dioxide insulation, polycrystalline silicon gate electrodes and biasing resistors 30 1 -30 n and 31 1 -31 n , and its manufacture using conventional integrated circuit techniques is described. The control circuit acts as a linear resistor and provides a gain control of 40 db. |
