Small signal amplifier

Patent metadata

Field	Value
Publication number	US-10044325-B2
Application number	US-201615380021-A
Country	US
Kind code	B2
Filing date	Dec 15, 2016
Priority date	Dec 16, 2015
Publication date	Aug 7, 2018
Grant date	Aug 7, 2018

Abstract

An amplifier circuit, a voltage sensing apparatus, and an amplification method are disclosed. The amplifier circuit comprises (1) an input stage comprising a first set of transistors to which an input signal to be amplified is applied, the transistors of the first set comprising a semiconductor body, and (2) a processing stage comprising a second set of transistors for processing the signal from the input stage and generating an output signal. The transistors of the first set have a thicker gate oxide than the transistors of the second set, and are therefore suitable for higher voltage operation. The first and second sets of transistors are supplied by the same voltage supply of the amplifier circuit. The semiconductor body of the first set of transistors is connected to a reference potential to lower the threshold voltage.

First claim

What is claimed is:

1. An amplifier circuit comprising:
an input stage comprising a first set of transistors to which an input signal to be amplified is applied, the transistors of the first set comprising a semiconductor body; and
a processing stage comprising a second set of transistors for processing the signal from the input stage and generating an output signal,
wherein the transistors of the first set have a thicker gate oxide than the transistors of the second set, and wherein the transistors of the first set are therefore suitable for higher voltage operation, and wherein the first and second sets of transistors are supplied by a same voltage supply of the amplifier circuit, and
wherein the semiconductor body of the first set of transistors is connected to a reference potential so as to lower a threshold voltage of the first set of transistors, wherein the reference potential is connected to a reference input of the input stage via a high-pass filter.

2. The amplifier circuit of claim 1 , wherein the input stage comprises a differential amplifier, and wherein the first set of transistors comprises:
a first input transistor, wherein a first differential input is provided to a gate of the first input transistor; and
a second input transistor, wherein a second differential input is provided to a gate of the second input transistor.

3. The amplifier circuit of claim 1 , wherein the voltage supply of the amplifier circuit is less than 2V.

4. The amplifier circuit of claim 1 , wherein the reference potential is in a range from 0.3V to 1V.

5. The amplifier circuit of claim 1 , wherein the voltage supply of the amplifier circuit and the reference potential are different.

6. A voltage sensing apparatus for detecting a voltage of biological tissue, the voltage sensing apparatus comprising:
an electrode configured to measure a voltage from a portion of tissue, wherein the electrode comprises an exposed, electrically conductive, surface area; and
an amplifier circuit for receiving an electrode potential from the electrode as an input signal, the amplifier circuit comprising:
an input stage comprising a first set of transistors to which an input signal to be amplified is applied, the transistors of the first set comprising a semiconductor body; and
a processing stage comprising a second set of transistors for processing the signal from the input stage and generating an output signal,
wherein the transistors of the first set have a thicker gate oxide than the transistors of the second set, and wherein the transistors of the first set are suitable for higher voltage operation than the transistors of the second set, and wherein the first and second sets of transistors are supplied by a same voltage supply of the amplifier circuit, and
wherein the semiconductor body of the first set of transistors is connected to a reference potential so as to lower a threshold voltage of the first set of transistors.

7. The voltage sensing apparatus of claim 6 , wherein the amplifier circuit comprises an instrumentation amplifier with a high-pass filter connected in a feedback path.

8. The voltage sensing apparatus of claim 6 , wherein the input stage comprises a differential amplifier, and wherein the first set of transistors comprises:
a first input transistor, wherein a first differential input is provided to a gate of the first input transistor; and
a second input transistor, wherein a second differential input is provided to a gate of the second input transistor.

9. The voltage sensing apparatus of claim 6 , wherein the voltage supply of the amplifier circuit is less than 2V.

10. The voltage sensing apparatus of claim 6 , wherein the reference potential is in a range from 0.3V to 1V.

11. The voltage sensing apparatus of claim 6 , wherein the voltage supply of the amplifier circuit and the reference potential are different.

12. An amplification method, comprising:
processing an input signal using an input stage comprising a first set of transistors, the transistors of the first set comprising a semiconductor body;
processing the input signal from the input stage using a processing stage; and
generating an output signal using the processing stage, wherein the processing stage comprises a second set of transistors, and wherein the transistors of the first set have a thicker gate oxide than the transistors of the second set, and wherein the transistors of the first set are suitable for higher voltage operation than the transistors of the second set;
supplying the first and second sets of transistors with a voltage supply; and
connecting the semiconductor body of the first set of transistors to a reference potential to lower a threshold voltage of the first set of transistors, wherein the reference potential is connected to a reference input of the input stage via a high pass filter.

13. The method of claim 12 , wherein the input signal is a differential input signal, and wherein processing the input signal using the input stage further comprises providing a first differential input to a gate of a first input transistor of the input stage, and providing a second differential input to a gate of a second input transistor of the input stage.

14. The method of claim 12 , further comprising supplying the first and second sets of transistors with a voltage supply of less than 2V.

15. The method of claim 12 , wherein the reference potential is in a range from 0.3V to 1V.

16. The method of claim 12 , wherein the voltage supply of the first and second sets of transistors and the reference potential are different.

17. The amplifier circuit of claim 1 , wherein the high-pass filter has a corner frequency of less than 10 Hz.

18. The method of claim 12 , wherein the high-pass filter has a corner frequency of less than 10 Hz.

Assignees

• Imec Vzw

Inventors

• Mora Lopez Carolina
• Mitra Srinjoy

Classifications

• H03F2203/45342

  the AAC comprising control means on a back gate of the AAC · CPC title

• H03F3/45475

  using IC blocks as the active amplifying circuit · CPC title

• H03F3/45188

  Non-folded cascode stages · CPC title

• H03F2200/261

  Amplifier which being suitable for instrumentation applications · CPC title

• H03F3/45183

  Long tailed pairs (H03F3/4521, H03F3/45237 take precedence) · CPC title