| 摘要 |
A variable gain frequency mixer is provided to acquire a variable gain of wide range at a low power voltage without connecting variable gain amplifiers in series by combining a variable gain amplifier and a mixer. A couple of analog input signals(LO+ and LO-) are inputted to a variable gain amplifier composed of two couples of transistors(Qp+/Qp- and Qn+/Qn-) as two couples of transistors. A mixer has a predetermined gain by outputting an output signal to one couple of two couple of transistors. A bias circuit has two bias output signals which are outputted to two couples of transistors, and two input signals which are shared to each other. The two couples of transistors(Qp+/Qp- and Qn+/Qn-) form a current steering variable gain amplifier.
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