发明名称 |
Suppressing channel-dependent spurious signals in fractional-N synthesizer |
摘要 |
A device for suppressing spurious signals generated by a fractional-N synthesizer. The fractional-N synthesizer generates an output frequency where an underlying PLL circuit uses a frequency divider for dividing the output frequency by a frequency-division ratio to obtain a comparison frequency and performs phase-comparison operations between a reference frequency and the comparison frequency to control the output frequency. The output frequency is changed by a frequency interval smaller than the reference frequency by making a temporal change to the frequency-division ratio once in every predetermined number of cycles. The device for suppressing spurious signals includes a current-generation unit which generates an electrical current proportional to a value representing an ordinal position of a current cycle in the every predetermined number of cycles, and a current-summation unit which adds the electrical current to another electric current controlling the output frequency in synchronism with the phase-comparison operations for a duration proportional to a cycle of the output frequency.
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申请公布号 |
US6317476(B1) |
申请公布日期 |
2001.11.13 |
申请号 |
US19980143654 |
申请日期 |
1998.08.31 |
申请人 |
FUJITSU LIMITED |
发明人 |
OISHI KAZUAKI;NIRATSUKA KIMITOSHI |
分类号 |
H03L7/089;H03L7/197;(IPC1-7):H04L25/36 |
主分类号 |
H03L7/089 |
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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