| 摘要 |
PROBLEM TO BE SOLVED: To provide a variable gain voltage/current conversion circuit, namely, a gm amplifier which can greatly change a gain range without using a large number of elements. SOLUTION: A parallel circuit of a positive resistor R1 (R2) and a transistor Q3 (Q4) which function as negative resistance is connected in series to transistors Q1 and Q2 for converting voltage/current. A variable voltage source VV is connected between Q3 (Q4) and ground, and a voltage value is controlled to control the resistance value of Q3 (Q4). When the voltage of the variable voltage source VV is changed, the resistance value of Q3 (Q4) changes. Thus, the voltage between the gates/sources of the transistors Q1 and Q2 changes and its gm value also changes. COPYRIGHT: (C)2004,JPO&NCIPI
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