●●● ●●●● ●●●● ●●●● 2.Image Frequency ●●●● ●●●● ●●●● For down-conversion frrl=fio+fiF,fRE2=fLo-fr They are indistinguishable at the IF stage,unless to reselect the signal and stop the noise or interference.它们在 中频没有差别，需要预先选出信号，抑制噪声或干扰， ② fio=fs±fiF noise of LO 本振的噪声 ③ f1o-fRF =fv fiu-fLo=fLo-fRE Two times mixing二次混频 fLo is the two times harmonies of LO,coming from inside or outside of mixer.f方Lo是本振的二次 谐波，来自于混频器的内外 6
2. Image Frequency ① For down-conversion They are indistinguishable at the IF stage, unless to reselect the signal and stop the noise or interference. 它们在 中频没有差别，需要预先选出信号，抑制噪声或干扰. ② noise of LO 本振的噪声 f2Lo is the two times harmonies of LO, coming from inside or outside of mixer. f2LO是本振的二次 谐波，来自于混频器的内外 ③ Two times mixing 二次混频 10 20 , RF L IF RF L IF f f ff f f L RF IF 0 fff f20 I L RF M f f IM L L RF 0 0 ff ff 6
●●● ●●● ●●●● ●●●● 3.Conversion loss ●●●● ●●●● ●●●● PRE ● Lc=10g Pir 1 It comes from resistive losses and frequency conversion process.它来自于阻性损耗和频率变换过程 2 Diode mixers have conversion losses several dB. 二极管混频器的变频损耗是几个分贝 ③ Transistor mixers have lower conversion loss and may have conversion gain. 晶体三极管混频器变频损耗小，甚至可以获得变频增益 Minimum Lc often occurs for LO power between 5 and 13dBm,which means nonlinear analysis is required. 为了获得最小的变频损耗，本振功率在5~13dBm之间，这意味着需要 采用非线性分析
3. Conversion loss ① It comes from resistive losses and frequency conversion process.它来自于阻性损耗和频率变换过程 ② Diode mixers have conversion losses several dB. 二极管混频器的变频损耗是几个分贝 ③ Transistor mixers have lower conversion loss and may have conversion gain. 晶体三极管混频器变频损耗小，甚至可以获得变频增益 ④ Minimum L C often occurs for LO power between 5 and 13dBm, which means nonlinear analysis is required. 为了获得最小的变频损耗，本振功率在 5 ～13dBm之间，这意味着需要 采用非线性分析。 10lg RF C IF P L P 7