Common Mode Interference Suppression In An Amplifier Circuit For A Neuromodulation Device

Patent metadata

Field	Value
Publication number	US-2025073450-A1
Application number	US-202418818054-A
Country	US
Kind code	A1
Filing date	Aug 28, 2024
Priority date	Aug 29, 2023
Publication date	Mar 6, 2025
Grant date	—

Abstract

The present disclosure provides a neuromodulation device that comprises at least one amplifier circuit that suppresses a common mode (CM) voltage signal in the input voltage signal. The amplifier circuit comprises an input stage to receive the input voltage signal, and a differential transconductor to provide an output current signal based on a DM voltage signal in the input voltage signal. The transconductor is provides a first CM voltage signal tapped after a non-inverting input, and a second CM voltage signal tapped after am inverting input, to CM amplifier of the amplifier circuit. The CM amplifier combines the first CM voltage signal with the second CM voltage signal, amplifies the combined CM voltage signal with an inverting gain, and provides the inverted CM voltage signal back to the non-inverting input and the inverting input of the transconductor for enabling the CM suppression.

First claim

What is claimed is:

1 . An amplifier circuit for amplifying a biological electrical signal, the amplifier circuit comprising:
an input stage with two input terminals, configured to receive an input voltage signal, which is based on the biological electrical signal and comprises a common mode, CM, voltage signal and a differential mode, DM, voltage signal; a differential transconductor comprising a non-inverting input and an inverting input, each connected to one of the two input terminals, and comprising an output for providing an output current signal based on the DM voltage signal; wherein the transconductor is configured to provide a first CM voltage signal, which is tapped after the non-inverting input, and a second CM voltage signal, which is tapped after the inverting input; and a CM amplifier configured to combine the first CM voltage signal with the second CM voltage signal to obtain a combined CM voltage signal, amplify the combined CM voltage signal with an inverting gain to obtain an inverted CM voltage signal, and provide the inverted CM voltage signal to the non-inverting input and the inverting input of the transconductor.

2 . The amplifier circuit of claim 1 , comprising:
a first capacitive feedback line configured to feedback the inverted CM voltage signal from the CM amplifier to the non-inverting input of the transconductor; and a second capacitive feedback line configured to feedback the inverted CM voltage signal from the CM amplifier to the inverting input of the transconductor; wherein each of the first and the second capacitive feedback line comprises a first capacitor.

3 . The amplifier circuit of claim 2 , wherein:
each of the non-inverting input and the inverting input of the transconductor is connected to one of the two input terminals of the input stage via a respective second capacitor; and the second capacitor has a higher capacitance than the first capacitor.

4 . The amplifier circuit of claim 1 , wherein:
each of the non-inverting input and the inverting input of the transconductor is connected to one of the two input terminals of the input stage via a respective second capacitor; and the second capacitor has a higher capacitance than the first capacitor.

5 . The amplifier circuit of claim 1 , wherein the transconductor comprises:
a first transistor connected with its gate to the non-inverting input and coupled with its source to a supply voltage; a second transistor connected with its gate to the inverting input, connected with its source to the source of the first transistor, and coupled with its source to the supply voltage; a third transistor connected with its gate to the non-inverting input, connected with its drain to the drain of the first transistor, and coupled with its source to a ground voltage; and a fourth transistor connected with its gate to the inverting input, connected with its drain to the drain of the second transistor, connected with its source to the source of the third transistor, and coupled with its source to the ground voltage; wherein the first CM voltage signal is tapped between the sources of the first and the second transistor, and the second CM voltage signal is tapped between the sources of the third and the fourth transistor.

6 . The amplifier circuit of claim 5 , configured such that a tail current of the source-connected third and fourth transistor is higher than a tail current of the source-connected first and second transistor in use of the amplifier circuit.

7 . The amplifier circuit of claim 6 , wherein the CM amplifier comprises:
a summing junction at which the first CM voltage signal and the second CM voltage signal are combined into the combined CM voltage signal; wherein each of the first CM voltage signal and the second CM voltage signal is connected to the summing junction via a respective third capacitor.

8 . The amplifier circuit of claim 7 , wherein:
the CM amplifier further comprises a gain circuit including a second transconductor, a fourth capacitor and a first resistor; and the gain circuit is configured to amplify the combined CM voltage signal with the inverting gain to produce the inverted CM voltage signal.

9 . The amplifier circuit of claim 1 , wherein the CM amplifier comprises:
a summing junction at which the first CM voltage signal and the second CM voltage signal are combined into the combined CM voltage signal; wherein each of the first CM voltage signal and the second CM voltage signal is connected to the summing junction via a respective third capacitor.

10 . The amplifier circuit claim 1 , further comprising:
a DM feedback circuit configured to provide a feedback voltage signal, which is based on the output current signal of the transconductor, to the non-inverting input and the inverting input of the transconductor.

11 . The amplifier circuit of claim 10 , wherein:
the DM feedback circuit comprises a first capacitive feedback path and a second capacitive feedback path; and each capacitive feedback path comprises a respective fifth capacitor that is connected in parallel to a respective second resistor.

12 . A neuromodulation device for measuring one or more biological electrical signals in response to a neural modulation of biological tissue, wherein the neuromodulation device comprises one or more amplifier circuits including:
an input stage with two input terminals, configured to receive an input voltage signal, which is based on the biological electrical signal and comprises a common mode, CM, voltage signal and a differential mode, DM, voltage signal; a differential transconductor comprising a non-inverting input and an inverting input, each connected to one of the two input terminals, and comprising an output for providing an output current signal based on the DM voltage signal; wherein the transconductor is configured to provide a first CM voltage signal, which is tapped after the non-inverting input, and a second CM voltage signal, which is tapped after the inverting input; and a CM amplifier configured to combine the first CM voltage signal with the second CM voltage signal to obtain a combined CM voltage signal, amplify the combined CM voltage signal with an inverting gain to obtain an inverted CM voltage signal, and provide the inverted CM voltage signal to the non-inverting input and the inverting input of the transconductor.

13 . The neuromodulation device of claim 12 , further comprising:
an array of electrodes comprising a first set of electrodes and a second set of electrodes, wherein each electrode of the first set is connected to a respective amplifier circuit of the one or more amplifier circuits, and wherein each electrode of the second set is configured to cause a respective neural modulation of the biological tissue.

14 . The neuromodulation device of claim 13 , wherein each electrode of the second set of electrodes comprises a stimulator, which is configured to provide a stimulation signal to cause the neural modulation of the biological tissue.

15 . The neuromodulation device of claim 14 , comprising:
multiple of the amplifier circuits; wherein the amplifier circuits share a single CM amplifier; and the CM amplifier is configured to provide, for each of the amplifier circuits, a respective inverted CM voltage signal to the non-inverting input and the inverting input of the transconductor of that amplifier circuit.

16 . The neuromodulation device of claim 12 , comprising:
multiple of the amplifier circuits; wherein the amplifier circuits share a single CM amplifier; and the CM amplifier is conf

Assignees

• Imec Vzw

Inventors

• Sawigun Chutham
• Lopez Carolina Mora
• Yang Xiaolin
• Aymerich Joan

Classifications

• H03F2203/45524

  the FBC comprising one or more active resistors and being coupled between the LC and the IC · CPC title

• H03F2203/45512

  the FBC comprising one or more capacitors, not being switched capacitors, and being coupled between the LC and the IC · CPC title

• H03F2200/129

  there being a feedback over the complete amplifier · CPC title

• H03F3/45475

  using IC blocks as the active amplifying circuit · CPC title

• A61N1/36025

  for treating a mental or cerebral condition · CPC title