| 摘要 |
PURPOSE: A phase detector for controlling automatically offset current and a phase locked loop having the same are provided to synchronize stably a phase and minimize the amount of offset current. CONSTITUTION: A Gilbert cell(31) is formed with a couple of emitter-combined transistor(Q39,Q41) and transistors couples(Q31,Q33,Q35,Q37). The Gilbert cell(31) outputs a voltage signal corresponding to a phase difference between the first input signal(MODout) and the second input signal(MIXout). The Gilbert cell(31) has a current source(35). The current source(35) is formed by a current mirror. A collector of the current source(35) is connected with emitters of the emitter-combined transistor couple(Q39,Q41). An emitter of a transistor(Q45) is connected with a ground power source. A transistor(Q43) is connected with a base and a collector of the transistor(Q45). A conversion portion(33) has a multitude of current mirror.
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