| 摘要 |
PROBLEM TO BE SOLVED: To provide a voltage controlled oscillator that can suitably be integrated into an integrated circuit(IC), effectively generate a local signal for portable telephones and by which a control range with a wide oscillating frequency can be obtained without increasing its current consumption. SOLUTION: A differential output from a differential amplifier consisting of transistors(TRs) Q1, Q2 is given to variable phase shift circuits PS1, PS2 via an emitter follower circuit including TRs Q3, Q4. The differential output from the differential amplifier is positively fed back to the differential input of the differential amplifier after passing through the variable phase shift circuits PS1, PS2. Moreover, each of the variable phase shift circuits PS1, PS2 employs a varactor diode Cv and the phase shift amount can be varied under the control of a control voltage Vt.
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