| 摘要 |
PURPOSE:To obtain an active filter that ensures the high band cut-off characteristics by using an FET having a high cut-off frequency or a bipolar transistor as an active element. CONSTITUTION:An active filter includes a GaAs type FET 7 having a high cut-off frequency and an FET 11. The drains of both FETs 7 and 11 are connected to an output terminal 12 via capacitors 9 and 10 respectively. The gate of the FET 7 is connected to a 1st power supply terminal 4 via a 1st resistor 3 as well as to an input terminal 1 via a capacitor 2 respectively as a control electrode. At the same time, the source of the FET 7 is grounded as an input electrode with the drain connected to a 2nd power supply terminal 5 via a 2nd resistor 6 as an output electrode. While the FET 11 is connected to a 3rd power supply terminal 15 via a gate resistor 14 as well as the terminal 1 via a capacitor 13 respectively. Then the source of the FET 11 is grounded together with the drain connected to the terminal 5 respectively via a resistor 8.
|
