High dynamic range sensing front-end for neural signal recording systems

Patent metadata

Field	Value
Publication number	US-10778165-B2
Application number	US-201515515562-A
Country	US
Kind code	B2
Filing date	Sep 30, 2015
Priority date	Sep 30, 2014
Publication date	Sep 15, 2020
Grant date	Sep 15, 2020

Abstract

A high dynamic range sensing front-end for bio-signal recording systems in accordance with embodiments of the invention are disclosed. In one embodiment, a bio-signal amplifier includes an input signal, where the input signal is modulated to a predetermined chopping frequency, a first amplifier stage, a parallel-RC circuit connected to the first amplifier stage and configured to generate a parallel-RC circuit output by selectively blocking an offset current, a second amplifier stage connected to the parallel-RC circuit that includes a second input configured to receive the parallel-RC circuit output and generate a second output that is an amplified version of the input signal with ripple-rejection. Further, the bio-signal amplifier can also include an auxiliary path configured for boosting input impedance by pre-charging at least one input capacitor. In addition, the bio-signal amplifier can also include a DC-servo feedback loop that includes an integrator that utilizes a duty-cycled resistor.

First claim

What is claimed is:

1. A bio-signal amplifier comprising:
an input signal comprising an input voltage and an input current, where the input signal is modulated to a predetermined chopping frequency;
a first amplifier stage comprising a first input configured to receive the modulated input signal and generate a first output, where the first output comprises an offset current and a portion of the modulated input current;
a parallel-RC circuit connected to the first amplifier stage and configured to receive the first output and generate a parallel-RC circuit output by selectively blocking the offset current utilizing at least one RC resistor and at least one RC capacitor;
a second amplifier stage connected to the parallel-RC circuit comprising a second input configured to receive the parallel-RC circuit output and generate a second output, where the second output is an amplified version of the input signal with ripple-rejection.

2. The bio-signal amplifier of claim 1 , further comprising an auxiliary path configured for boosting input impedance by pre-charging at least one input capacitor.

3. The bio-signal amplifier of claim 2 , wherein the auxiliary path is set to an enable configuration by connecting the at least one input capacitor to an auxiliary path buffer.

4. The bio-signal amplifier of claim 3 , wherein the auxiliary path is set to a disable configuration by connecting the at least one input capacitor to an input electrode.

5. The bio-signal amplifier of claim 1 , wherein the parallel-RC circuit acts as an open-circuit to the first amplifier stage when the at least one RC resistor is greater than an output impedance of the first amplifier stage.

6. The bio-signal amplifier of claim 1 , wherein, the parallel-RC circuit acts as a short circuit at the chopping frequency when the impedance of the at least one RC capacitor is less than an output impedance of the first amplifier stage.

7. The bio-signal amplifier of claim 1 , wherein the parallel-RC circuit output is demodulated by the predetermined chopping frequency before being received by the second amplifier stage.

8. The bio-signal amplifier of claim 1 , wherein the first output and the first input are connected by a first feedback loop comprising a first feedback resistor.

9. The bio-signal amplifier of claim 1 , wherein the second output and the second input are connected by a second feedback loop comprising a second feedback resistor and a second feedback capacitor.

10. The bio-signal amplifier of claim 1 , wherein the second output and the first input are connected by a third feedback loop comprising a third feedback capacitor.

11. The bio-signal amplifier of claim 2 , wherein the second output and the first input are connected by a DC-servo feedback loop comprising an integrator that utilizes a duty-cycled resistor, wherein the duty-cycled resistor is connected in series to a DC-servo feedback switch configured to periodically remove the duty-cycled resistor from the DC-servo feedback loop.

12. The bio-signal amplifier of claim 5 , wherein the at least one RC resistor is connected in series to a RC switch configured to periodically remove the at least one RC resistor from the RC circuit.

13. The bio-signal amplifier of claim 8 , wherein the first feedback resistor is connected in series to a first feedback switch configured to periodically remove the first feedback resistor from the first feedback loop.

14. The bio-signal amplifier of claim 11 , wherein the second output is connected to an anti-aliasing filter.

15. The bio-signal amplifier of claim 1 , wherein the parallel-RC circuit does not include active circuit elements.

16. The bio-signal amplifier of claim 1 , wherein the parallel-RC circuit adds nominal area to the amplifier's total area.

Assignees

• Univ California

Inventors

• Chandrakumar Hariprasad
• Markovic Dejan

Classifications

• H03F2200/261

  Amplifier which being suitable for instrumentation applications · CPC title

• H03M1/48

  Servo-type converters · CPC title

• H03F2200/168

  Two amplifying stages are coupled by means of a filter circuit · CPC title

• A61B5/30

  Input circuits therefor · CPC title

• H03F2200/459

  Ripple reduction circuitry being used in an amplifying circuit · CPC title