| 摘要 |
The present invention provides a voltage-current converting circuit which is capable of varying a gain in a wide range without a switching circuit by applying a control voltage to a single control terminal. The voltage-current converting circuit is comprised of a parallel circuit including positive resistors R 1 and R 2, and transistors Q 3 and Q 4 each acting as a negative resistor, and electrically connected in parallel with the positive resistors R 1 and R 2, and transistors Q 1 and Q 2 each carrying out voltage-current conversion and electrically connected in series to the parallel circuit. A variable voltage source VV is electrically connected between the transistors Q 3, Q 4 and a ground. By controlling a voltage of the variable voltage source VV, resistances of the transistors Q 3 and Q 4 are controlled. By varying a voltage of the variable voltage source VV, resistances of the transistors Q 3 and Q 4 vary, resulting in that a voltage between a gate and a source in the transistors Q 1 and Q 2 varies, and thus, a mutual conductance gm of the voltage-current converting circuit varies.
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