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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 t

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.

대표청구항 ▼

An implantable cardiac pacer for delivering therapy to a heart, said cardiac pacer comprising: a first connection point through which an input signal can be received by said cardiac pacer; a second connection point through which a therapeutic output signal can be delivered by said cardiac pacer; a p

An implantable cardiac pacer for delivering therapy to a heart, said cardiac pacer comprising: a first connection point through which an input signal can be received by said cardiac pacer; a second connection point through which a therapeutic output signal can be delivered by said cardiac pacer; a pace amplifier coupled to the second connection point so as to deliver the therapeutic output signal to the second connection point; a pacing controller, coupled to the pace amplifier, that causes the pace amplifier to generate therapeutic output signal; a sense amplifier coupled between the pacing controller and the first connection point that receives the input signal from the first connection point; said sense amplifier including a band-pass filter circuit comprising: a first bilinear resistor coupled between a terminal (A) and a terminal (B), said terminal (A) being coupled to the first connection point, a first capacitor that is coupled between the terminal (B) and a terminal (C), a second capacitor that is coupled between the terminal (B) and a terminal (D), said terminal (D) being coupled to the pacing controller, a second bilinear resistor that is coupled between the terminal (C) and the terminal (D), an operational amplifier with an inverting input that is coupled to the terminal (C), a non-inverting input that is coupled to analog ground, and an output that is coupled to the terminal (D), said first bilinear resistor comprising a switching means for coupling a first lead of a first capacitive element to said terminal (A) and for coupling a second lead of the first capacitive element to said terminal (B) in response to a first state of at least one control signal, and for coupling the first lead of the first capacitive element to terminal (B) and for coupling second lead of the first capacitive element to terminal (A) in response to a second state of the at least one control signal, whereby the electrical orientation of the first capacitive element can be oscillated relative to the terminal (A) and the terminal (B) in response to said first and second states.