mydreamhouse
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Posts: 23
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now, i am simulating a receiver with cadence spectre, it is a typical heterodyne receiver, which including LNA, first Mixer, IF filter,second mixer, baseband filter,VGA and ADC. all the block are connected with packge model( no couple between pins) except the ADC and i make a TRAN analysis, the output of receiver is fine. but if i add the ADC clock and ADC block into top view ( there is no connection between ADC and the other circuit), a strange result appears, the RF signal is abnormal, which is disturbed by ADC clock. after my carefully checking, i found that if there is a steep transient block in circuit, such as VPULSE, whether it is connected with others ,the accuracy of the RF blocks is affected by the block. so the result is abnormal. By the way, the accuracy of TRAN is moderate. if i change it to conservative or set relref to allocal, the output is fine. i'm hoping reply from Ken, thanks
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