| 摘要 |
An automatic gain adjustment circuit for automatically adjusting the gain and DC output voltage of an amplifier against power supply fluctuations, temperature fluctuations and process variations and the amplifier using the circuit are provided. The gain and the DC output voltage are adjusted by providing a bias circuit for adjusting the operating current or gain of an amplifying element, connecting a load to the output electrode of the amplifying element to form an output terminal, connecting a variable current source for adjusting the operating voltage or DC output voltage of the amplifying element to the output electrode, connecting a gain detection circuit and a DC output voltage detection circuit to the output terminal, and feed backing the respective outputs of the detection circuits to the variable current source. A reference AC signal is inputted for gain adjustment. After the adjustment, changeover to a signal for amplifying the input is performed, while the output of the gain detection circuit is held in a Sample & Hold circuit.
|
