低噪声放大器中共源结构与共栅结构对噪声的影响

semico_ljj

交流阻抗50 Ohm？

feilang6882

回复 10# hezudao


    是在片的，也有COB的，做的感觉都是差不多的。现在总结设计的过程，感觉还是有很多问题。如果不是在片的，是不是级联时LNA后面的buffer阻抗较大，或者后级混频器的输入阻抗也较高，从而共源共栅增益高呢？

feilang6882

回复 11# semico_ljj


   单级的LNA，一个独立的IP，输出匹配至50欧姆的

hezudao

回复 12# feilang6882


    You need to make the difference between microwave IC and RFIC (nowadays, more and more microwave ICs become RFICs). If you design individual blocks (LNA,mixer,etc.), and then connect them on PCB, for sure you need impedance matching. However, if you are designing RFIC (LNA,mixer,etc. are put together on the single chip, as most SOC does), impedance matching is not necessary, and actually it just makes design more difficult.

feilang6882

回复 14# hezudao


    明白了，非常感谢

liushengfu01

说得很好，问的也很好

rainman9112000

领教了:victory:

严皮皮

回复 6# hezudao

Have you ever simulated a common gate LNA with fixed gm?The best NF is 3dB?Books say so ,but simulation results prove it  wrong.Actully, simulation results show better NF and NFmin can be less than 1dB.

hezudao

回复 18# 严皮皮

tell me how you can get better than 3dB NF for simple CG LNA with input impedance matched. Unless for old large channel length, gamma is smaller than 1. BTW, I have never designed 'simple' CG LNA, since its theoretical limit is already bad.

严皮皮

回复 19# hezudao

    I doubt the minimum NF of CG.So I design a simple CG LNA using 0.18um BiCMOS.I found NF is less than 3dB and NFmin was better than 1dB.