I want to use LTC6946、ADL5904 and HMC637ALP5 on my circuit by ADS_2016. But I don't know where to download these component model.
It sounds like you are interested in S-parameters for ADS?
For the LTC6946
s-parameters: see page 26 and 27 of the LTC6946 datasheet.
IBIS models, they are at this website. http://www.linear.com/product/LTC6946
To simulate phase noise and design loop filters: Download/Install PLLWizard http://www.linear.com/designtools/software/#Timing
S-Parameters for the ADL5904's RF input can be downloaded from www.analog.com/adl5904
HMC637 S-parameters are also located on its own product webpage:
HMC637ALP5 Datasheet and Product Info | Analog Devices
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