ASIC with switching noise reduction
Medical catheterization is carried out by receiving a plurality of analog bioelectric signals in respective channels and multiplexing the bioelectric signals in respective selection events. The selection events comprise making a first connection with a reference voltage, thereafter breaking the first connection and making a second connection with one of the bioelectric signals. The method is further carried out by outputting the multiplexed bioelectric signals to an analog-to-digital converter.
1. An apparatus comprising
a catheter having an elongated distal portion;
a plurality of electrodes on the distal portion for reading bioelectric signals:
a multiplexor having inputs connected to respective ones of the electrodes and having an output;
a switch having a first input terminal connected to a reference signal, a second input terminal linked to the output of the multiplexor, and an output terminal; and
control circuitry linked to the switch and the multiplexor and operative to make a first connection between the output terminal of the switch and the reference signal via the first input terminal of the switch; and thereafter to break the first connection and to make a second connection between the output terminal of the switch and the output of the multiplexor via the second input terminal of the switch,
wherein the control circuitry comprises a differential amplifier having first and second inputs and having first and second outputs connected to the first and second input terminals of the switch, respectively, wherein the first input of the differential amplifier is connected to a Wilson central terminal, and the second input of the differential amplifier is linked to one of the bioelectric signals.
2. The apparatus according to claim 1 , wherein the bioelectric signals are analog signals, further comprising an analog-to-digital converter connected to the output terminal of the switch and linked to a processor.
3. The apparatus according to claim 1 , wherein the switch is a double pole double throw switch.
4. The apparatus according to claim 1 , wherein the Wilson central terminal is connected to a dynamic offset voltage.