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PLL NOT WORKING IN TEMPERATURE

Sir,

Pls help to find an unlocking issue in PLL ckt using AD4156 and HMC587 VCO.It became unlock b/w the temperature range of +17 to +20 C.Freq is 5.5GHZ.It is working fine above and below this range.

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  • Sir,

    Finally I could find out the problem.The pad of LNA detached (very very small portion) from the body.The image attached is taken using a magnifier having 110 zoom.HMC 587 output is divided using…

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  • Sir,

    At these temperature , V TUNE voltage from AD4156 varies entire range and VCO sweeps frequency form 3 GHZ to 8 GHZ but not locking to the desired frequency.The mux out pin configured as lock detector and it is not becomes high at these temperature range.After this particular temperature window,it automatically locks and will get a stable output.Phase comparison for AD4156 given thru 16MHZ crystal osc.Also I replaced this ,but still problem is there.Pls suggest some solution,Sir.

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  • Sir,

    At these temperature , V TUNE voltage from AD4156 varies entire range and VCO sweeps frequency form 3 GHZ to 8 GHZ but not locking to the desired frequency.The mux out pin configured as lock detector and it is not becomes high at these temperature range.After this particular temperature window,it automatically locks and will get a stable output.Phase comparison for AD4156 given thru 16MHZ crystal osc.Also I replaced this ,but still problem is there.Pls suggest some solution,Sir.

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