45 lines
1.1 KiB
Markdown
45 lines
1.1 KiB
Markdown
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---
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title: HMC835
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updated: 2022-02-14 09:38:33Z
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created: 2022-01-08 13:17:43Z
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---
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# AUXSPI
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可用于锁定指示，配置输出，默认电平1.8V，限流电阻0R即可
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锁定时总消耗电流约180mA
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# 同步
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HMC835具备同步功能，
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需要==Exact Frequency Channel Mode==
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需要==CHIP_EN==作为触发
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# 小数分频与Exact Frequency Channel Mode的差异
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1. 确保VCO频率Fvco与鉴相频率Fpd的最大公因数gcd大于Fpd/2^24
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1. 03H 分离出整数部分 分离出整数部分
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1. 0CH Fpd/gcd
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1. 04H round(小数部分*2^24) ceil(频差/Fpd*2^24)
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满足条件1需要：
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Fpd（MAX）=100MHz，Fpd/2^24=6，<10
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最大频率分辨率＞10Hz则gcd＞=10;频率分辨率=100Hz则gcd＞=100
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考虑到计算方便，参考误差等因素，基于HMC835的PLL建议最大频率分辨率为==10Hz==，则可满足Exact Frequency Channel Mode的需求
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综上，可直接替换小数模式。
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# 输出
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HMC835具备两路输出，可同时可独立，可单端可差分，单端时只能使用N脚
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