功率信号和电压信号如何转换？
做接收机的时候，射频到中频的信号都是按照功率来计算的，而到了A/D的时候，它的输入要求却是按照电压来计算的，我想问下这个怎么换算?按照多大的阻抗来将功率信号换算为电压信号?
弱弱的回一句…… 难道是用检波器?
我是射频新人，BS我的话可以邮箱联系:njduoyue@126.com
也欢迎各位大大与我联系。
查下器件资料
用信号源改变输入信号，测出对应关系，对器件公式做修正
It depends on how you design you AD circuits. Usually, a balun is used to transform single-end signal to differential signal. The transforming ratio needed to be designed. You then can calculate the corresponding impedance at the each path (+ / -); in most case, for example you use 1:4 transform, the calculated characteristic impedance is 100Ohm (for this, I am not very sure, I did not worked on it for quite a long time, you need to check some application notes, ADI provides very good notes which you can refer); then you can calculate the corresponding voltage value (RMS one, not peak one) with power, then you can check if the input IF signal is large enough and decide whether amp or att. is needed;
a little bit lengthy, you better check ADI app notes, equations are there
Thanks a lot for ksyao.
And how can I get the ADI application notes? Do you send a web-address for me?
Thanks！
find the app notes at http://www.analog.com/
or this
http://search.analog.com/search/default.aspx?query=adc&contentType=Application_Notes&local=en
Thank you,ksyao.
ADC检测的是电压 不是功率
我们的接收机为了射频角度的考虑方便都做成了50欧姆匹配
只是到最后了才用一个BALUN进行单双转换给ADC
其实很多MIXER都是射频端单端进中频端差分出的
SAW也是差分进差分出
完全可以在MIXERER输出端就用全差分的结构
这个很多老外的基站厂商老早就这么做了
只是国内的少见而已
多谢楼上的答复，非常感谢！
继续关注学习中。