| 摘要 |
PURPOSE:To make the stability against load variance excellent, by providing mutually a series/parallel circuit for a filter having a cut-off frequency lower than the operating frequency of a high frequency transistor power amplifier and a filter terminated with a resistor. CONSTITUTION:One end of a resistor 3 is grounded and another end is connected to the input terminal of a low-pass filter 4. The output terminal of a high-pass filter 2 and that of the filter 4 are connected to the input terminal of a power amplifier 6 consisting of high frequency transistors. The filter 2 is constituted that it is at a high impedance at lower frequencies than the operating frequency of the amplifier 6 by viewing an input power terminal 1 from a terminal 5 of the amplifier 6. Further, the cut-off frequency of the filter 4 is lower than the operating frequency of the amplifier 6. Thus, at lower frequencies than the operating frequency, the resistor 3 can be existed at all time by viewing the terminal 1 from the terminal 5, even if the load condition of the prestage is fluctuated from the terminal 1. |
