The active filter acts as an infinite impedance to the external for the fundamental frequency and as a low resistor for harmonic frequencies.
对外电路而言，在基波频率下有源滤波器被控制为无限大阻抗，在谐波频率下被控制为小电阻。
2
Simulation results indicate that dual slope algorithm is of high stability during external faults and is very sensitive to high impedance internal faults.
仿真结果表明：双比率算法较单比率算法，具有外部故障高稳定性，而在内部高阻故障时，也有很高的灵敏度。
3
They have a simple construction with low power dissipation and low output impedance and can be used as interfacing circuits in VLSI designs to reduce the number of external connections on a chip.