| 摘要 |
A low-power band-pass filter for use in a cardiac pacer includes a single operational amplifier connected in circuit relationship with a plurality of switched capacitors that function as bilinear resistors. Each bilinear resistor comprises a switch for coupling a first lead of a capacitive element to a first terminal and for coupling a second lead of the capacitive element to a second terminal in response to a first state of a control signal, and for coupling the first lead of the capacitive element to the second terminal and for coupling the second lead of the capacitive element to the first terminal in response to a second state of the control signal. Thus, the bilinear resistor switches or oscillates the electrical orientation of the capacitive element between the first terminal and the second terminal in response to the first and second states of the control signal. The invention also includes a method of operating such an implantable filter circuit. Such method includes the steps of: (a) oscillating periodically the electrical orientation of the capacitive element of each bilinear resistor in a prescribed manner; while (b) applying an input signal to the band-pass filter circuit while such oscillation occurs.
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