| 摘要 |
PURPOSE: To improve the mount efficiency on a printed circuit board by employing one operational amplifier, capacitors and resistors so as to allow the circuit to act like a high pass filter with plural-input provision whose characteristic is expressed in a quadratic function of a positive feedback. CONSTITUTION: One-terminal of a resistor R1 connects to an output terminal of an operational amplifier OP and each one-terminal of a capacitor C2 and a resistor R2 is connected to an input terminal of the operational amplifier. The other terminal of the resistor R2 connects to a common line and each one-side terminal of n-sets of capacitors C11 -C1n is connected to the other terminal of the capacitor C2 and a common connecting point of the other terminal of the resistor R1 . Then an output voltage V0 with respect to input voltages V1 -Vn is expressed in equation 1, which is similar to a transfer function of a positive feedback type high pass filter thereby realizing a high pass filter with plural-input provision, whereωis an angular frequency of the input voltages, Q is the sharpness, H is a circuit constant andωis a cut-off frequency.
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