发明名称 |
Voltage controlled oscillator phase locked loop circuit with loop filter capacitance tuning |
摘要 |
A phase locked loop circuit comprises a voltage controlled oscillator with a control input to which a variable control voltage is applied and a phase-frequency discriminator with an output connected to a loop filter to produce the control voltage. To provide the phase locked loop circuit with a low loop gain and a wide frequency pulling range, a plurality of discrete capacitors is associated with the voltage controlled oscillator. A switch array selectively activates and deactivates each of the capacitors in the voltage controlled oscillator. Each number of currently activated capacitors determines one out of a plurality of partial ranges of frequencies through which the oscillator can be tuned by a variation of the control voltage in a range between predetermined upper and lower control voltage limits. A total frequency range through which the oscillator can be tuned is divided thus into a plurality of partial frequency ranges each defined by a different number of activated capacitors.
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申请公布号 |
US7408415(B2) |
申请公布日期 |
2008.08.05 |
申请号 |
US20050288004 |
申请日期 |
2005.11.28 |
申请人 |
TEXAS INSTRUMENTS DEUTSCHLAND GMBH |
发明人 |
DIELT MARKUS;WERKMEISTER ELMAR |
分类号 |
H03L7/00 |
主分类号 |
H03L7/00 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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