| 摘要 |
PURPOSE:To increase the dynamic range of an input voltage by providing a level shift 2-terminal element between a power supply with a high potential of an SCFL and a load and adding the level shift 2-terminal element between a source terminal of an FET constituting a source follower circuit and the load. CONSTITUTION:When a voltage over a voltage Vref is applied to an input terminal 210, a current Ic all flows to a FET200 and a forward voltage drop -Vf of a diode 100 appears at the drain terminal of a FET201. On the other hand, when a voltage below the voltage Vref is fed to the input terminal 210, the current Ic flows to the FET201 and the drain voltage of the FET201 is -Vf-RIc, the output voltage always shows a value of -Vf of below to prevent a FET206 from being unsaturated. An SCFL output voltage is fed to a gate terminal of the FET206 and shifted further by the forward voltage Vf by the operation of a diode 101. In allowing the source follower to burden part of the level shift in this way, the reduction in the dynamic range of the SCFL input is prevented. |
