1 김명준 Dept. of Biomed. Eng.BME303:Applied Electronic CircuitKyung Hee Univ. Applied Electronic Circuit # 김명준

2 김명준 Dept. of Biomed. Eng.BME303:Applied Electronic CircuitKyung Hee Univ. Instrumentation Amplifier : IA 2 High Input Impedance Low Output Impedance Accurate and Stable Gain (1 ~ 1000) High CMRR

3 김명준 Dept. of Biomed. Eng.BME303:Applied Electronic CircuitKyung Hee Univ. Instrumentation Amplifier : IA 3 For CMRR Tuning 이득가변

4 김명준 Dept. of Biomed. Eng.BME303:Applied Electronic CircuitKyung Hee Univ. Instrumentation Amplifier : IA 4 Differential Mode Input – Differential Mode Output Amplifier One Chip Instrumentation Amplifier AD620 or etc

5 김명준 Dept. of Biomed. Eng.BME303:Applied Electronic CircuitKyung Hee Univ. Dual OP AMP Instrumentation Amplifier 5 Gain 조절 쉽지 않다

6 김명준 Dept. of Biomed. Eng.BME303:Applied Electronic CircuitKyung Hee Univ. Ground loop 6 Stray capacitor 도선 자체 저항 실제로는 도선에 연결된 Capacitor 가 아닌 매질을 통해 연결된 가상의 Capacitor

7 김명준 Dept. of Biomed. Eng.BME303:Applied Electronic CircuitKyung Hee Univ. Ground loop 7 CMRR 감소의 원인 R 감소 방법 : lead wire 를 짧고 굵은 선으로 !

8 김명준 Dept. of Biomed. Eng.BME303:Applied Electronic CircuitKyung Hee Univ. Shield Cable 8 절연체 cable 도자기 도체 절연체 coaxial cable Triaxial cable

9 김명준 Dept. of Biomed. Eng.BME303:Applied Electronic CircuitKyung Hee Univ. Shield 9 220V 60Hz Shield( 차폐 ) : 적절한 전압 유지 도체 ( 등전위면 ) Grounded Shield( 접지 차폐 ) Chassi s

10 김명준 Dept. of Biomed. Eng.BME303:Applied Electronic CircuitKyung Hee Univ. Shield V 60Hz Ground Shield Shield 가능 전원 전압에 의한 interference 제거 오히려 더 나빠진다 → 원치 않는 DM current 더 생겨 Leakage Current increased + - IA Shield 불가능

11 김명준 Dept. of Biomed. Eng.BME303:Applied Electronic CircuitKyung Hee Univ. Shield 11 Active Shield (Driven Shield) + - IA Cable 에 흐르는 전압과 같은 전압을 Shield 에 Drive

12 김명준 Dept. of Biomed. Eng.BME303:Applied Electronic CircuitKyung Hee Univ. Shield 12 Active Shield & Ground Shield - + 전체가 Ground Shield

13 김명준 Dept. of Biomed. Eng.BME303:Applied Electronic CircuitKyung Hee Univ. Transducer Bridge Amplifier 13 Resistive Sensor Temperature ; Thermister, RTD Light ; Photoresistor Strain ; Straingage Pressure ; piezo resistive sensor 물리량의 변화 -> 저항의 변화 -> 전압의 변화

14 김명준 Dept. of Biomed. Eng.BME303:Applied Electronic CircuitKyung Hee Univ. Bridge Circuit 14 AC 사용할 수 있음 Capacitive sensor Inductive Sensor → Balanced

15 김명준 Dept. of Biomed. Eng.BME303:Applied Electronic CircuitKyung Hee Univ. Conduction in Metal (Conductor) 15 + e mobility n; 자유전자의 부피밀도 전류밀도 conductivity =

16 김명준 Dept. of Biomed. Eng.BME303:Applied Electronic CircuitKyung Hee Univ. Conduction in Metal (Conductor) 16 N 개의 Free electron A L

17 김명준 Dept. of Biomed. Eng.BME303:Applied Electronic CircuitKyung Hee Univ. Conduction in Metal (Conductor) 17 온도계수 (Temp wett.)

18 김명준 Dept. of Biomed. Eng.BME303:Applied Electronic CircuitKyung Hee Univ. Conduction in Metal (Conductor) 18 Ex. Pt RTD

19 김명준 Dept. of Biomed. Eng.BME303:Applied Electronic CircuitKyung Hee Univ. Conduction in Metal (Conductor) 19 Ex. Pt RTD (xA)

20 김명준 Dept. of Biomed. Eng.BME303:Applied Electronic CircuitKyung Hee Univ. Conduction in Metal (Conductor) 20 Ex. Pt RTD To prevent self heating 최종적으로 0.1V/ ℃의 출력을 얻기 위하여 margin

21 김명준 Dept. of Biomed. Eng.BME303:Applied Electronic CircuitKyung Hee Univ. Conduction in Metal (Conductor) 21 Ex. Pt RTD 근사식이 아닌 식을 사용하면, 근사식인 경우에 비해 약 0.26 ℃ 차이 발생

22 김명준 Dept. of Biomed. Eng.BME303:Applied Electronic CircuitKyung Hee Univ. Bridge Balancing 22 1% 저항, 5% 전원 사용 Bridge Arm 에 흐르는 전류를 제어 → 민감도 조절 ⓐ Balancing ( 영점 조정 ) 14-16V 0-2V 2mA 14V 1mA (xA)

23 김명준 Dept. of Biomed. Eng.BME303:Applied Electronic CircuitKyung Hee Univ. Bridge Balancing 23 To be safe, ⓐ점의 전압 =14V To be safe,