MSP430 Applicationin the medical equipment industry (4)
source: icbuy million core time: 2012-04-05-
ECG signal preamplifier circuit and
ECG signal is obtained by surface electrode electrical signal is very weak and in the process of ECG signal detection is accompanied by strong interference, therefore, must be approved by the special processing can be used for clinical diagnosis. This design uses a precision instrumentation amplifier INA326 TI company, eight channel ECG signal acquisition circuit design, the simultaneous extraction of I, II and V1 - V6 eight - lead ECG signals, the other four ECG signal is in after ADC transform in digital processing part according to the need of realization of the use of I guide and II guide group. ECG signal preamplifier circuit as shown in figure 2. The level of common-mode signal by the measured by the left, right and left, the circuit in the front stage adds a common-mode signal drive, used to reduce the output impedance common-mode signals and improving the common-mode signal driving ability, ensure that the common-mode signal level in the multi-channel case stability. After the instrument amplifier INA326 8 ECG signal, INA326 can remove the AC line noise common to double input and amplifies the input than DC signal end of the residual, the high magnification ECG signal is sent to the ADC sampling circuit. Ro, Co for the output filter, noise can be output filtering circuit, also can be used as an input filter circuit with ADC. INA326 uses a unique internal technology to achieve excellent common-mode rejection ratio. In order to realize the high frequency CMR better, a small capacitance with between 2 and 3 feet, then with the positive input end resistance at the same time on the same resistance at the inverting input end of the instrument amplifier, in order to reduce influence of INA326 input bias current on the output signal.
