| 摘要 |
PURPOSE:To eliminate noise due to a parasitic capacitance by connecting a back gate terminal of an analog switch consisting of MOSFETs to a constant voltage source and using a positive/negative stable voltage as a control signal applied to the gate terminal. CONSTITUTION:An output of a signal processing circuit AC having a stable constant voltage source is given to the back gate of P channel PS1 and PS2 of the MOSFETs constituting the analog switch. Further, the circuit AC is connected also to one end of resistors R1, R2 increasing the gate voltage of the FETs PS1, PS2, NS1 and NS2 to a constant voltage Vc. The other end of the resistors R1, R2 is connected to a drain of the FETs NB1, NB2. The gate of the FETs NB1 and NB2 is controlled by a logic circuit CLC controlling the sequence of operation of a range finder, its drain voltage becomes a line GND potential when the FETs NB1, NB2 are turned on and reaches a potential of a line LVc when they are turned off. |
