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Title:
VOLTAGE-CONTROLLED OSCILLATOR AND PHASE SYNCHRONIZATION CIRCUIT USING THE SAME
Document Type and Number:
Japanese Patent JP2008311862
Kind Code:
A
Abstract:

To reduce phase noise not only when a MOS transistor which constitutes an inverter cell operates in a saturated region but also in a linear region.

A voltage-controlled oscillator comprises a ring oscillator and a dummy inverter 110. The ring oscillator includes inverter cells 100 connected in a circular pattern. Each inverter cell 100 comprises: an operational amplifier 120 which outputs an amplified signal obtained by amplifying a potential difference between a signal from a dummy inverter cell 110 and a reference signal; a first MOS transistor 101 which is connected to a second MOS transistor 102 and receives the amplified signal; a second MOS transistor 102 and a third MOS transistor 103 serving as an inverter input portion and an inverter output portion, respectively; and a fourth MOS transistor 104 which is connected to the third MOS transistor 103 and receives a control signal for controlling the frequency of an oscillation signal. The dummy inverter 110 has the same structure as the inverter cells 100 and has its inverter output portion short-circuited to its inverter input portion.


Inventors:
SAI AKIHIDE
Application Number:
JP2007000156579
Publication Date:
December 25, 2008
Filing Date:
June 13, 2007
Export Citation:
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Assignee:
TOSHIBA CORP
International Classes:
H03K3/354; H03L7/099
Attorney, Agent or Firm:
鈴江 武彦
河野 哲
中村 誠
蔵田 昌俊
峰 隆司
福原 淑弘
村松 貞男
橋本 良郎