| 摘要 |
PROBLEM TO BE SOLVED: To provide an amplifier circuit with less fluctuation in gain and the gain of which is inversely proportionated to the gain control current. SOLUTION: The amplifier circuits consisting of a differential input stage MDn and a load stage MLn are serially connected at two stages. The gain is controlled by controlling current to be supplied to load transistors ML1, ML2, ML3, ML4 and changing the gm at a load stage. The fluctuation in the gain is less since the gain is set in a ratio of the gm as differential input stage gm/load stage gm. The current is inversely proportional to√current in the amplifier circuit at one stage, however, the gain is made proportional to the current by serially connecting the amplifier circuits at two stages. |
