发明名称 |
VCO DRIVING CIRCUIT AND FREQUENCY SYNTHESIZER |
摘要 |
<p>A VCO driving circuit and a frequency synthesizer wherein the impedance viewed from a VCO control terminal is reduced to prevent the VCO phase noise characteristic from degrading. A VCO driving circuit and a frequency synthesizer having the VCO driving circuit, which comprises a coarse adjustment DAC (4) that receives a digital data, which has a coarse adjustment frequency, to output an analog signal; a fine adjustment DAC (6) that receives a digital data, which has a fine adjustment frequency, to output an analog signal; a low response speed LPF (5) that removes noise from the output signal from the coarse adjustment DAC (4) and then provides the resultant signal as an input to a VCO control terminal; a high response speed LPF (7) that converts the output signal from the fine adjustment DAC (6) to a voltage, thereby smoothing the signal; a resistor (R6) that connects an input stage of the LPF (5) to that of the LPF (7); and a capacitor (C8) used for providing a capacitive coupling such that the output of the LPF (7) is added to that of the LPF (5).</p> |
申请公布号 |
EP1976126(A1) |
申请公布日期 |
2008.10.01 |
申请号 |
EP20070707488 |
申请日期 |
2007.01.26 |
申请人 |
NIHON DEMPA KOGYO CO., LTD. |
发明人 |
KITAYAMA, YASUO;KIMURA, HIROKI;ONISHI, NAOKI;TSUKAMOTO, NOBUO |
分类号 |
H03L7/087;H03L7/093 |
主分类号 |
H03L7/087 |
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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