| 摘要 |
PROBLEM TO BE SOLVED: To apply base charge to an LO port quickly and to improve the linearity. SOLUTION: A mixer section 34 connects to a post mixer linearizing section 36 to cancel a nonlinear mutual conductance characteristic of an RF input section of a mixer and then a linear response range of the mixer is extended. The post mixer linearizing section 36 has a response characteristic to increase the nonlinearity of the RF input section at the outside of a nonlinear operating range. The nonlinearity response characteristic compensates the nonlinearity response characteristics of the RF input section. Current mirrors 80, 82 of the post mixer linearizing section 36 increases the margin of a rail-to-rail voltage of a mixer while keeping a high gain. An input driver 32 is connected to the mixer to quicken the switching of transistors(TRs) in the mixer thereby reducing the effect of noise. The mixer has a gain control circuit conducting linear decibel gain control.
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