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Dept. of Biomed. Eng. BME302: Medical Instrumentation Kyung Hee Univ. 1 최최최 Biomedical Instrumentation Report 7 2010103819 최최최

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Biomedical Instrumentation. Report 7 2010103819 최법경. Contents. Bio-potential A mplifier Design Design signal range Power and devises Stray capacitance Design circuit with IA A part B part C part D part. Bio-potential Amplifier Design. Design signal range BW : 0.05 – 100Hz - PowerPoint PPT Presentation

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Page 1: Biomedical Instrumentation

Dept. of Biomed. Eng. BME302: Medical Instrumentation Kyung Hee Univ.

1 최법경

Biomedical Instrumenta-tion

Report 7

2010103819

최법경

Page 2: Biomedical Instrumentation

Dept. of Biomed. Eng. BME302: Medical Instrumentation Kyung Hee Univ.

2 최법경

Contents

• Bio-potential Amplifier Design

• Design signal range

• Power and devises

• Stray capacitance

• Design circuit with IA• A part• B part• C part• D part

Page 3: Biomedical Instrumentation

Dept. of Biomed. Eng. BME302: Medical Instrumentation Kyung Hee Univ.

3 최법경

Bio-potential Amplifier Design• Design signal range

• BW : 0.05 – 100Hz• 신호의 주파수 성분이 0.05 – 100Hz

따라서 나머지 주파수 성분은 필요없다는 것을 알 수 있다 .

• DC contact potential : 300mV

• Ag/AgCl 의 DC contact potential 은100mV 이지만 최악의 경우를 생각해 넉넉하게 잡는다

• Contact impedance : 10kΩ

• 피부의 Contact impedance 를 줄이려면 각질을 제거한다 .따라서 일반적인 경우를 생각해 넉넉하게 잡는다 .

5mV range

Page 4: Biomedical Instrumentation

Dept. of Biomed. Eng. BME302: Medical Instrumentation Kyung Hee Univ.

4 최법경

Bio-potential Amplifier Design• Power and devises

• ADC 입력범위 : 5V

• Power supply : 9V

• Op amp : 6V 에서 포화

전원 및 소자는 이런 범위에서 전원을 공급하고 입출력을 받는다고 하자 .

Page 5: Biomedical Instrumentation

Dept. of Biomed. Eng. BME302: Medical Instrumentation Kyung Hee Univ.

5 최법경

Bio-potential Amplifier Design• Stray capacitance

• 부유 용량이라고도 하고 Parasitic capacitance( 기생 용량 ) 이라고도 한다 .이번 회로 디자인에서는 공기와 사람 사이 부유 용량이 문제가 된다 . 그림과 같이 원래 보기에는 커페시터가 보이지 않지만 도선과 도선 사이에 자그마한 커페시터가 존재하는 것 처럼 작동하는 것 그 커페시터를 부유용량이라고 한다 .

Page 6: Biomedical Instrumentation

Dept. of Biomed. Eng. BME302: Medical Instrumentation Kyung Hee Univ.

6 최법경

Bio-potential Amplifier Design• Design circuit with IA

V ec g

LA

RA

RL

+Vi-

Page 7: Biomedical Instrumentation

Dept. of Biomed. Eng. BME302: Medical Instrumentation Kyung Hee Univ.

7 최법경

Bio-potential Amplifier Design• Design circuit with IA

• 참고 motion artifact

Page 8: Biomedical Instrumentation

Dept. of Biomed. Eng. BME302: Medical Instrumentation Kyung Hee Univ.

8 최법경

Bio-potential Amplifier Design• Design circuit with IA

• 전체 회로도

+3

-2

V +8

V -4

O U T1

R 1

R 1

R 3 R 4

R 3

R 4

R 5

R 6 R 7

R 11

R 4_v a r

0

1n

0

+3

-2

V +8

V -4

O U T1

0

1n

0

0

+5

-6

V +8

V -4

O U T7

1n

0

0

+3

-2

V +8

V -4

O U T1

C 81n

0

R 2

0

C 1

0

0

C 2

Page 9: Biomedical Instrumentation

Dept. of Biomed. Eng. BME302: Medical Instrumentation Kyung Hee Univ.

9 최법경

Bio-potential Amplifier Design• A part

+

3

-2

V +8

V -4

O U T1

R 1

R 1

0

1n

0

+3

-2

V +8

V -4

O U T1

0

1n

0

R 2

𝑣 𝐿𝐴

𝑣𝑅𝐴

𝑖1=𝑉 1−𝑉 2

𝑅𝐺

𝑉 1

𝑉 2

300mV 305mV

Page 10: Biomedical Instrumentation

Dept. of Biomed. Eng. BME302: Medical Instrumentation Kyung Hee Univ.

10 최법경

Bio-potential Amplifier Design• B part (Differential Amp)

• Dc offset 이 함께 증폭된다는 문제점 발생

여기서 이득율이 낮은게 CMRR 이 커진다 .

R 3 R 4

R 3

R 4

R 4_v a r

0

+5

-6

V +8

V -4

O U T7

1n

0

0

𝑣3

4.5mV

4.575mV

Page 11: Biomedical Instrumentation

Dept. of Biomed. Eng. BME302: Medical Instrumentation Kyung Hee Univ.

11 최법경

Bio-potential Amplifier Design• C part (High pass filter)

• 차단 주파수

R 5

C 1

0

𝑣4

75mV

𝑣3

Page 12: Biomedical Instrumentation

Dept. of Biomed. Eng. BME302: Medical Instrumentation Kyung Hee Univ.

12 최법경

Bio-potential Amplifier Design• D part (Non-inverting amp with low pass filter)

• R 6 R 7

R 11

0

+3

-2

V +8

V -4

O U T1

C 81n

0

0

C 2

𝑣5𝑣4

5V