Specifications for biopotential measurement system, type ActiveThree with two-wire active electrodes :

 

Subject isolation BF (Body Floating)
Number of channels
 0 to 136 monopolar active electrodes + 6 bipolar auxiliary sensors
Output sample-rate (down-sampling available in software) 16384 Hz
Bandwidth (-3dB): DC – 5.4 kHz, 0.002 dB ripple in passband
Low-pass response 140 tap FIR filter, -65 dB @ 8 kHz (Nyquist frequency)
High-pass response fully DC coupled
Digitalization: 24 bit SAR converter with 8x oversampling and integrated decimation filter, one converter per channel, synchronous sampling
Sampling skew and jitter: < 1 ns
Sample rate accuracy 0.8 Hz
Quantization-resolution LSB = 31.25 nV, guaranteed no missing codes
Gain accuracy: 0,1 %
Anti aliasing filter 1st order analog filter, -3dB at 7.8 kHz
Total input noise (Ze < 10 kOhm):, full bandwidth 2.8 uVRMS (approx. 15 uVpk-pk), see Fig. 1, noise spectrum
1/f noise (Ze < 100 kOhm), 0.1 - 10Hz 2 uVpk-pk , see Fig. 2, pink noise plot
Amplifier/input current noise: < 1 pArms
Input bias current: < 100 pA per channel
Input impedance Active Electrode 600 MOhm @ 50 Hz (1012 Ohm // 5 pF)
DC offset: < 2 mV
Input range +200 mV to -200 mV
Intermodulation distortion, test signals: 2990 and 3010 Hz < 0.01 %
Channel separation > 100 dB
Common Mode Rejection Ratio > 100 dB @ 50 Hz
Isolation Mode Rejection Ratio > 160 dB @ 50 Hz
Power Consumption 0.5 Watt (6 channels) to 1 Watt (142 channels)
Battery capacity, standard battery 4000 mAh, 3.7 V Li-ion 18650 type
Battery life on standard battery 10 hours (142 channels) to 20 hours (6 channels)
Leakage current, normal operation: < 1 uA rms.
Leakage current, single fault  < 40 uArms
Trigger inputs: 16 inputs on optical receiver (isolated from subject section) , TTL level 
Trigger outputs: 12 outputs on optical receiver (isolated from subject section) , TTL level 
Computer interface: USB2.0, Windows or Linux
Size of front-end, including battery-box (H x W x D) 162 x 149 x 62 mm
Weight of AD-box, including battery 0.8 kg
Environment: Indoor use Temperature: +10°C to +40°C
Humidity: 30 to 75%, non condensing
Pressure: 700 hPa to 1060 hPa
Warranty 3 years
Conformity EN61326 (EMC), EN60601-1 (safety)
     
Final Noise of the ActiveThree Active Electrodes   Pink Noise of the ActiveThree Active Electrodes
Fig. 1: Noise spectrum of 1 channel referenced to the average of 128 channels. The area under the curve (the total noise) is 2.8 uVrms. Note that spectrum is completely free of spikes by spurious tones.  
Fig. 2: Plot of the 1/f (pink) noise of 1 channel referenced to the average of 128 channels and filtered with a 0.1 - 10 Hz bandpass filter.
         
ABR Noise with Frequency Extending Down to 10 Hz    
Area under the curve (the total noise) is 0.35 uVrms and the noise density at 1 kHz is 5 nV/Hz^1/2 (vs. 3.9 uVrms and 50 nV/Hz^1/2 for a pair of standard active electrodes). Ignore the spikes by mains supply interference (50 Hz and odd harmonics). The ActiveThree ABR sensor has a factor of 10 lower noise than standard active electrodes.
 

ABR sensor specifications:

  - Sampling rate: 16,384 Hz
- Bandwidth (-3dB): 10 Hz to 5.4 kHz
- AC input range: 16 mV peak-to-peak
- DC input range: -0.7 V to +0.7 V
- Noise over full bandwidth: 0.35 Vrms, approx. 2 uV peak-to-peak
- CMRR: 140 dB
- Quantization resolution: LSB is 1.95 pV (1/512 uV)