JPS6449319A - Analog switch driving circuit - Google Patents

Abstract

PURPOSE:To suppress a leak current at the time of a holding mode, to a value which can be disregarded, by preventing a drift caused by the fluctuation of a temperature, a power source, etc., with respect to a base current at the time of ON of a bipolar transistor for constituting an analog switch, and fixing a base voltage at the time of OFF, to a prescribed voltage or below. CONSTITUTION:At the time of a holding mode, a transistor Q becomes an OFF state, therefore, a base current IB of the transistor Q becomes zero. Also, a base power source VB in this case becomes a base power source V1 for constituting a voltage limiter 13, and V1-0.6[V] determined by base-emitter voltage VBE5 of a transistor Q5, and a base voltage VB of the transistor Q is fixed to this value. At the time of OFF of the transistor Q, when the base voltage VB is, for instance, a value of <=1V, a leak current IL becomes a small value of the extent that it can be disregarded. Also, at the time of OFF of the transistor Q, that is, at the time of a holding mode, a temperature characteristic of the base-emitter voltage VBE5 of the transistor Q5 is not compensated, but in this case, as well, the leak current IL can be set to the prescribed value of the extent that it can be disregarded, by suppressing the base voltage VB to the prescribed voltage or below.