Figure 1.
Typical block diagram of AFE for ECG signal acquisition.
Figure 1.
Typical block diagram of AFE for ECG signal acquisition.
Figure 2.
Simplified block diagram of the work in this paper.
Figure 2.
Simplified block diagram of the work in this paper.
Figure 3.
Two-stage OTA with Miller Compensation.
Figure 3.
Two-stage OTA with Miller Compensation.
Figure 4.
Design flow for design and optimization of OTA.
Figure 4.
Design flow for design and optimization of OTA.
Figure 5.
Schematic diagrams for gm/ method curve generation. (Left) P-channel MOSFET. (Right) N-channel MOSFET.
Figure 5.
Schematic diagrams for gm/ method curve generation. (Left) P-channel MOSFET. (Right) N-channel MOSFET.
Figure 6.
vs. Vov plot for p-channel MOS device at W = 1 m and L = 1 m, 5 m, 10 m.
Figure 6.
vs. Vov plot for p-channel MOS device at W = 1 m and L = 1 m, 5 m, 10 m.
Figure 7.
Characteristic curves for the input pairs (). (a) vs. for W = 1 m. (b) vs. for W = 1 m. (c) vs. Vov for W = 1 m.
Figure 7.
Characteristic curves for the input pairs (). (a) vs. for W = 1 m. (b) vs. for W = 1 m. (c) vs. Vov for W = 1 m.
Figure 8.
Characteristic curves for the active loads (). (a) vs. for W = 1 m. (b) vs. for W = 1 m.
Figure 8.
Characteristic curves for the active loads (). (a) vs. for W = 1 m. (b) vs. for W = 1 m.
Figure 9.
Characteristic curves for and . (a) vs. for W = 1 m. (b) vs. for W = 1 m. (c) vs. Vov for W = 1 m.
Figure 9.
Characteristic curves for and . (a) vs. for W = 1 m. (b) vs. for W = 1 m. (c) vs. Vov for W = 1 m.
Figure 10.
Characteristic curves for the input driver (). (a) vs. for W = 1 m. (b) vs. for W = 1 m. (c) vs. Vov for W = 1 m.
Figure 10.
Characteristic curves for the input driver (). (a) vs. for W = 1 m. (b) vs. for W = 1 m. (c) vs. Vov for W = 1 m.
Figure 11.
Characteristic curves for the active load (). (a) vs. for W = 1 m. (b) vs. for W = 1 m. (c) vs. Vgs for W = 1 m.
Figure 11.
Characteristic curves for the active load (). (a) vs. for W = 1 m. (b) vs. for W = 1 m. (c) vs. Vgs for W = 1 m.
Figure 12.
Frequency response of designed OTA for the first iteration.
Figure 12.
Frequency response of designed OTA for the first iteration.
Figure 13.
DC operating points of the OTA circuit from simulation.
Figure 13.
DC operating points of the OTA circuit from simulation.
Figure 14.
, Vov and vs. figures for p-channel MOS devices for W = 1 m and L = 5 m.
Figure 14.
, Vov and vs. figures for p-channel MOS devices for W = 1 m and L = 5 m.
Figure 15.
ft x vs. Vov plot for p-channel MOS device at W = 1 m and L = 5 m.
Figure 15.
ft x vs. Vov plot for p-channel MOS device at W = 1 m and L = 5 m.
Figure 16.
Design flow for design and optimization of filters.
Figure 16.
Design flow for design and optimization of filters.
Figure 17.
Proposed ECG acquisition circuit diagram.
Figure 17.
Proposed ECG acquisition circuit diagram.
Figure 18.
Test-bench for dc, ac, transient, noise, pole-zero analyses.
Figure 18.
Test-bench for dc, ac, transient, noise, pole-zero analyses.
Figure 19.
Magnitude response of the designed OTA.
Figure 19.
Magnitude response of the designed OTA.
Figure 20.
Pole zero map of the OTA.
Figure 20.
Pole zero map of the OTA.
Figure 21.
CMRR waveform vs. frequency.
Figure 21.
CMRR waveform vs. frequency.
Figure 22.
PSRR waveform vs. frequency.
Figure 22.
PSRR waveform vs. frequency.
Figure 23.
Output voltage spectrum of the designed OTA for an input sinusoidal of 100 Hz and 0.4 mV p-p.
Figure 23.
Output voltage spectrum of the designed OTA for an input sinusoidal of 100 Hz and 0.4 mV p-p.
Figure 24.
Output impedance of the Operational Trans-conductance Amplifier.
Figure 24.
Output impedance of the Operational Trans-conductance Amplifier.
Figure 25.
Input impedance of the operational trans-conductance amplifier.
Figure 25.
Input impedance of the operational trans-conductance amplifier.
Figure 26.
Input impedance of the operational trans-conductance amplifier for an input capacitance of 100 pF.
Figure 26.
Input impedance of the operational trans-conductance amplifier for an input capacitance of 100 pF.
Figure 27.
Threshold voltage deviation distribution.
Figure 27.
Threshold voltage deviation distribution.
Figure 28.
Test-bench for the final ECG acquisition system.
Figure 28.
Test-bench for the final ECG acquisition system.
Figure 29.
Magnitude response of the whole ECG system.
Figure 29.
Magnitude response of the whole ECG system.
Figure 30.
Pole-zero locations of the ECG system.
Figure 30.
Pole-zero locations of the ECG system.
Figure 31.
Input-referred noise density.
Figure 31.
Input-referred noise density.
Figure 32.
(Left) ECG spectrum with added noise at 50 Hz and 500 Hz. (Right) Output voltage spectrum of the designed ECG acquisition system.
Figure 32.
(Left) ECG spectrum with added noise at 50 Hz and 500 Hz. (Right) Output voltage spectrum of the designed ECG acquisition system.
Figure 33.
Output of the ECG acquisition system for noisy inputs.
Figure 33.
Output of the ECG acquisition system for noisy inputs.
Figure 34.
THD for various amplitudes and frequencies.
Figure 34.
THD for various amplitudes and frequencies.
Figure 35.
(a) Layers used in layout. (b) Post-layout view for the instrumentation amplifier OTA.
Figure 35.
(a) Layers used in layout. (b) Post-layout view for the instrumentation amplifier OTA.
Figure 36.
Post-layout magnitude response of the instrumentation amplifier OTA.
Figure 36.
Post-layout magnitude response of the instrumentation amplifier OTA.
Figure 37.
Post-layout CMRR waveform vs. frequency.
Figure 37.
Post-layout CMRR waveform vs. frequency.
Figure 38.
Post-layout PSRR waveform vs. frequency.
Figure 38.
Post-layout PSRR waveform vs. frequency.
Figure 39.
Post-layout input impedance of the operational trans-conductance amplifier.
Figure 39.
Post-layout input impedance of the operational trans-conductance amplifier.
Figure 40.
Post-layout output voltage spectrum of the designed OTA for an input sinusoidal of 100 Hz and 0.4 mV p-p.
Figure 40.
Post-layout output voltage spectrum of the designed OTA for an input sinusoidal of 100 Hz and 0.4 mV p-p.
Figure 41.
The proposed ECG filter circuit layout without the pad frame.
Figure 41.
The proposed ECG filter circuit layout without the pad frame.
Figure 42.
The proposed ECG acquisition system post-layout frequency response.
Figure 42.
The proposed ECG acquisition system post-layout frequency response.
Figure 43.
The proposed ECG acquisition system post-layout input-referred noise.
Figure 43.
The proposed ECG acquisition system post-layout input-referred noise.
Figure 44.
Post-layout output of the ECG acquisition system for noisy inputs.
Figure 44.
Post-layout output of the ECG acquisition system for noisy inputs.
Table 1.
Summary of design requirements for individual MOSFETs of the two-stage Miller-compensated OTA.
Table 1.
Summary of design requirements for individual MOSFETs of the two-stage Miller-compensated OTA.
MOSFET | Inversion Region | Area | |
---|
| Moderate | Large | High to Medium |
| Strong | Small | Low |
| Strong | Small | Low |
| Moderate | Large | High to Medium |
| Strong | Small | Low |
Table 2.
Design specifications for the two-stage Miller-compensated OTA.
Table 2.
Design specifications for the two-stage Miller-compensated OTA.
Parameter | Value |
---|
| ±0.6 V |
| 200 nA |
GBW | 1.25 MHz |
Slew Rate | 0.67 V/s |
CMRR | High (≥60 dB) |
PSRR | High (≥60 dB) |
THD | Low (≤1%) |
| 2 pF |
Table 3.
Summary of dc operating points of each MOSFET device for the first iteration.
Table 3.
Summary of dc operating points of each MOSFET device for the first iteration.
MOSFET | Aspect Ratio (W/L) | | | |
---|
| 1/5 | −301.62 mV | 101.38 nA | 23.91 |
| 1/10 | 386.64 mV | 101.38 nA | 16.96 |
| 6/10 | −511.73 mV | 203.05 nA | 15.61 |
| 7/5 | 331.27 mV | 573.03 nA | 20.87 |
| 5/1 | −868.72 mV | 573.03 nA | 16.91 |
| 6/10 | −424.84 mV | 199.64 nA | 15.73 |
Table 4.
Design parameters for the two-stage Miller-compensated OTA of instrumentation amplifier.
Table 4.
Design parameters for the two-stage Miller-compensated OTA of instrumentation amplifier.
Parameter | Value |
---|
| ±0.6 V |
| 200 nA |
| 1 m/5 m |
| 1 m/10 m |
| 6 m/10 m |
| 7 m/10 m |
| 5 m/1 m |
Cc | 500 fF |
Table 5.
Finalized aspect ratios for the optimized OTAs.
Table 5.
Finalized aspect ratios for the optimized OTAs.
Parameter | IA | LPF | HPF | Notch |
---|
| 1 m/5 m | 2.5 m/5 m | 1 m/10 m | 1 m/5 m |
| 1 m/10 m | 1 m/10 m | 1 m/10 m | 1 m/10 m |
| 6 m/10 m | 6 m/10 m | 6 m/10 m | 6 m/10 m |
| 7 m/10 m | 1 m/10 m | 1 m/5 m | 5 m/5 m |
| 5 m/1 m | 0.9 m/0.9 m | 10 m/1 m | 7 m/1 m |
Table 6.
Design parameters for the proposed ECG acquisition system.
Table 6.
Design parameters for the proposed ECG acquisition system.
Parameter | Value |
---|
R1 | 300 M |
R2 | 32 M |
R3 | 16 M |
R4 | 10 M |
R5 | 99 M |
R6 | 190 M |
R7 | 400 M |
R8 | 900 M |
R9, R10 | 3.5 G |
R11 | 1 G |
Rvar1 | 60 M |
Rvar2 | 200 M |
C1 | 99.2 pF |
C2 | 198.4 pF |
C3 | 1.4 pF |
C4 | 900 pF |
Table 7.
Performance comparison of the proposed OTA with previously reported work.
Table 7.
Performance comparison of the proposed OTA with previously reported work.
Parameter | This Work | [19] | [20] | [21] |
---|
Tech (nm) | 45 | 350 | 180 | 180 |
Topology | Miller-OTA | CR-OTA 1 | GBFC-IBL 2 | MI-OTA 3 |
Supply (V) | ±0.6 | 2 | ±0.75 | ±0.5 |
(A) | 816 n | 160 n | 570 n | 200 n |
Power (nW) | 980 | 320 | 855 | 267.5 |
Gain (dB) | 64.5 | 39.8 | 47.6 | 31.17 |
PSRR (dB) | 76.55 | 70 | - | 37.26 |
CMRR (dB) | 66.55 | 65 | 105.6 | 90.05 |
THD (%) | <1 | <1 | <1 | <1 |
IRN (V) | 15.9 | 2.05 | 0.12 (PSD) | 174 |
Zin () | 5.1 | - | 0.3 | - |
Table 8.
Input-referred noise, power consumption, and total harmonic distortion for the filters.
Table 8.
Input-referred noise, power consumption, and total harmonic distortion for the filters.
Parameter | Second-Order HPF | Notch Filter | Fifth-Order LPF |
---|
Input-Referred Noise | 70.1 Vrms/ | 14 Vrms/ @ PB | 130 Vrms/ |
Power Consumption | 2.034 W | 2.67 W | 1.21 W |
Total Harmonic Distortion | −92.5 dB | −52.1 dB | −112.2 dB |
Table 9.
Performance comparison of the designed ECG acquisition system with contemporary designs.
Table 9.
Performance comparison of the designed ECG acquisition system with contemporary designs.
Parameters | This Work 1 | [58] 2 | [21] 1 | [61] 1 | [62] 1 | [63] 2 |
---|
Technology (nm) | 45 | 180 | 180 | 180 | 180 | 180 |
Supply (V) | ±0.6 | 1.8 | ±0.25 | 0.5 | 0.5 | 1 |
Order | HPF-2nd, LPF-5th | LPF-2nd | BPF-3rd | LPF-4th | BPF-2nd | LPF-5th |
Power (W) | 10.88 | 4.5–19.4 | 0.161 | 0.003 | 0.0313 | 0.041 |
Gain (dB) | 58.06 | 34.5 | 0 | −5.6 | 37.1 | −7 |
BW (Hz) | 0.08–239.6 | 1.7–352 | 0.1–250 | 200 | 1.5–112 | 250 |
IRN (V) | 33.6 | 3.47 | 198 | 91.9 | 17.9 | 134 |
PLI Removal | Notch | Notch | Notch | No | No | No |
Area (mm2) | 0.00628 (off-chip RC) | 156.25 | 0.0528 (off-chip cap) | 0.074 | 0.167 | 0.24 |
NEF | 10.43 | 2.99 | - | - | - | - |
Dynamic Range (dB) | 52.71 | - | 66.98 | 48.5 | 55.5 | 61.2 |