| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To realize a stable oscillation operation by avoiding a deterioration and a deadlock state in phase noise characteristics in an oscillator using a current controlled type oscillation circuit. <P>SOLUTION: Resistors Q1 and Q3 are inserted into respective current paths of a differential pair of a differential amplifier circuit constituting an oscillation frequency control circuit to relax inclination in linear areas of output currents Ia and Ib of the differential pair. Reference voltage to be applied to the base of one transistor of the differential pair is set low to thereby shift the linear area to a low voltage side, preventing the occurrence of a saturation area at the low voltage side. Further, when converting a comparison result in phase between an output signal of the current controlled oscillation circuit and the reference signal into oscillation frequency control voltage, upper limit voltage closer to an output of a regulator is limited in place of a positive voltage power supply Vcc common to the circuit to thereby prevent the voltage from moving to a saturation area that is an upper side of the linear area. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
