确定LTE接收机的半中频寄生要求，并选择适当的射频混频器

　　There is a particularly troublesome second-order spurious response called the half-IF （1/2 IF） spurious response， defined for the mixer indices of （m = 2， n = -2） for low-side LO injection and （m = -2， n = 2） for high-side LO injection （Figure 1）。 For high-side injection， the input frequency that creates the half-IF spurious response is located above the desired RF frequency by an amount fIF/2 from the desired RF input frequency.

　　Consider an example where the desired RF frequency is centered at 2510MHz （E-UTRA uplink channel number 39790）。 When this RF frequency is combined with the LO frequency of 2860MHz， the resulting IF frequency is 350MHz. In this case， an undesired or blocking signal at 2685MHz causes a half-IF spurious product at 350MHz. For low-side injection， the input frequency that creates the half-IF spurious response is located above the desired LO frequency by an amount fIF/2.