发明名称 |
Direct digital frequency synthesizer and a hybrid frequency synthesizer combining a direct digital frequency synthesizer and a phase locked loop |
摘要 |
A direct digital frequency synthesizer and a hybrid frequency synthesizer combining the direct digital frequency synthesizer and a phase locked loop is provided. The direct digital frequency synthesizer includes a phase accumulator that is configured to generate a discrete phase signal. Spurious phase modulation in the discrete phase signal is reduced by a noise shaper, and the output of the noise shaper is then used to address a phase-to-amplitude translator. The phase-to-amplitude translator generates a discrete waveform which is converted to a continuous waveform by a digital to analog converter. The hybrid frequency synthesizer uses a mixer to combine a reference frequency generated by a reference source and a DDFS output signal generated by a direct digital frequency synthesizer. The output from the mixer is then coupled to the input of a phase locked loop which multiplies the mixer output to generate the frequency synthesizer output.
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申请公布号 |
US6483388(B2) |
申请公布日期 |
2002.11.19 |
申请号 |
US20010867829 |
申请日期 |
2001.05.30 |
申请人 |
RESEARCH IN MOTION LIMITED |
发明人 |
KHAN NASSERULLAH |
分类号 |
G06F1/03;H03B21/00;H03L7/06;H03L7/18;(IPC1-7):H03L7/00 |
主分类号 |
G06F1/03 |
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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