| 摘要 |
PURPOSE:To improve voltage resistance and an SN ratio by using a pMOS transistor(TR) for a constant current circuit connected to a common emitter of a differential circuit and using a series circuit consisting of an npn TR and a pMOS constant current source as an output stage. CONSTITUTION:When an 'H' level switching signal is inputted to a differential input In terminal of a switching driver, the 'H' level is compared with a REF level, so that a TR Q1 is turned off and TRs Q2, Q3 are turned on. Thereby, an output level eD of the switch driver is turned to about V<-> level, and when a pMOSTR is used as an analog switch Q4, the Q4 is turned off. Therefore, it is unnecessary to use an nMOS TR having low voltage resistance for an analog switch driver in a BiCMOS process. Consequently, the voltage resistance of a CT circuit system can be increased and a dynamic range and an SN ratio can be improved.
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