| 摘要 |
An adaptive proportional integral control loop ( 209, 210 ) provides an accurate measurement of input to output sampling rates for use in asynchronous sampling rate conversion. An input counter ( 200 ) counts inputs samples and its output is sampled at the output sampling rate by a latch ( 201 ). The output of the latch ( 201 ) is passed through a closed loop circuit ( 210 ) comprising variable gain ( 203, 205 ) and integrator ( 208 ) sections. The output of the integrator can be used to steer the co-efficients of a polyphase filter. The invention has the advantages of a fast settling time and good quantisation noise attenuation.
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