A 72- W 90-dB Wide-Range Potentiostatic CMOS Modulator with Flicker - - PowerPoint PPT Presentation

▶
a 72 w 90 db wide range potentiostatic cmos modulator
SMART_READER_LITE
LIVE PREVIEW

A 72- W 90-dB Wide-Range Potentiostatic CMOS Modulator with Flicker - - PowerPoint PPT Presentation

Jun 26, 2023 326 likes •705 views

72- W 90-dB Wide-Range Potentiostatic Modulator 1/22 A 72- W 90-dB Wide-Range Potentiostatic CMOS Modulator with Flicker Noise Cancellation for Smart Electrochemical Sensors J. Aymerich 1 , M. Dei 1 , L. Ters 1,2 , F. Serra-Graells 1,2

slide-1
SLIDE 1

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

A 72- W 90-dB Wide-Range Potentiostatic CMOS Modulator with Flicker Noise Cancellation for Smart Electrochemical Sensors

  • J. Aymerich1, M. Dei1, L. Terés1,2, F. Serra-Graells1,2

1/22

joan.aymerich@imb-cnm.csic.es

May 2019

1Instituto de Microelectrónica de Barcelona, IMB-CNM(CSIC), Spain 2Universitat Autònoma de Barcelona, Spain

slide-2
SLIDE 2

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

Sensors Maket Vision

Sensors/year Year

5 6 % / y e a r 21%/year 222%/year

Electrochemical sensors are growing exponentially due to potential of miniaturization and mass production

2/22

Several organizations created visions for continued growth to trillion(s) sensors Applications in biosensors, quality control, health care, ... Expected sensor production growth per year $15 trillion by 2022 www.eenewsanalog.com Monolithic or hybrid integration

  • nto CMOS platforms
slide-3
SLIDE 3

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

3/22

1 Amperometric Electrochemical Sensors Conclusions 2 Potentiostatic Modulator architecture 3 4 5 Proposed wide-range potentiostat with 1/f noise cancellation 0.18- CMOS Design and Post-Layout simulations

slide-4
SLIDE 4

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

3/22

1 Amperometric Electrochemical Sensors Conclusions 2 Potentiostatic Modulator architecture 3 4 5 Proposed wide-range potentiostat with 1/f noise cancellation 0.18- CMOS Design and Post-Layout simulations

slide-5
SLIDE 5

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

4/22

Amperometric Electrochemical Sensors

Electrochemical time constant: Measurement independent of the R and C impedances. Three electrodes: Interaction with microorganisms Interaction with microorganisms. Selectivity by functionalization. Reduced speed and life time. Potentiostatic and amperometric operations. Current associated to the electrons involved in a redox process: Linear model

slide-6
SLIDE 6

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

Classic circuit implementation

A1 establishes the control loop to accomplish potentiostat operation. & Requires multiples OpAmps + ADC. A2 converts sensor current to voltage for digitization and readout. Potentiostat Amperometry

6/22

Large area and power consumption.

slide-7
SLIDE 7

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

7/22

1 Amperometric Electrochemical Sensors Conclusions 2 Potentiostatic Modulator architecture 3 4 5 Proposed wide-range potentiostat with 1/f noise cancellation 0.18- CMOS Design and Post-Layout simulations

slide-8
SLIDE 8

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

Behaviour similar to low-pass first-order single-bit CT A/D modulator. Sensor-on-the-loop Error current converted into voltage and shaped in frequency by the electrochemical sensor itself. High OSR easly obtained with kHz-range clock frequencies.

1st order Potentiostatic

Amperometric read-out through the

  • utput by chemical input .

S/H Feedback DAC

Linear model 8/22

slide-9
SLIDE 9

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

S/H

Feedback DAC

Typical tonal component of 1st order DAC flicker noise not shaped by loop. Noise floor in the signal band (BW < 1Hz) dominated by flicker noise. Vpot only applies to the Reference Electrode (R). Limited potentiostatic range programmability (Vrw):

9/22

1st order Potentiostatic

slide-10
SLIDE 10

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

10/22

1 Amperometric Electrochemical Sensors Conclusions 2 Potentiostatic Modulator architecture 3 4 5 Proposed wide-range potentiostat with 1/f noise cancellation 0.18- CMOS Design and Post-Layout simulations

slide-11
SLIDE 11

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

From 1st to 2nd order

S/H Feedback DAC Quantizer Second-order noise shaper

Feedforward path

From electrochemical only to hybrid/mixed electrochemical/electronic Tones and pattern noise suppression.

11/22

slide-12
SLIDE 12

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

From 1st to 2nd order

S/H Feedback DAC Quantizer Second-order noise shaper

Feedforward path

From electrochemical only to hybrid/mixed electrochemical/electronic Tones and pattern noise suppression. Small-signal model 2nd order requires stability compensation LHP Zero through feedforward path

Feedforward path

11/22

slide-13
SLIDE 13

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

Wide-range potentiostatic 2nd order

Programmable-WE through Gm1: Extend potentiostatic range virtually up to double the supply voltage:

Feedback DAC

12/22

slide-14
SLIDE 14

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

Programmable-WE through Gm1: Extend potentiostatic range virtually up to double the supply voltage: Small-signal model High power consumption on Gm1 to push RHP zero to high frequencies: Loop stability:

Feedback DAC

12/22

Wide-range potentiostatic 2nd order

slide-15
SLIDE 15

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

Differential DAC wide-range potentiostatic 2nd order

Programmable-WE through Gm1: Extend potentiostatic range virtually up to double the supply voltage

Feedback DAC

13/22

slide-16
SLIDE 16

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

Differential DAC wide-range potentiostatic 2nd order

Programmable-WE through Gm1: Extend potentiostatic range virtually up to double the supply voltage Small-signal model Loop stability:

RHP self-canceled both Ifsp,n are used in both quantization symbols. Gm1 only has to cope with Ifsp,n mismatching.

Feedback DAC

13/22

slide-17
SLIDE 17

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

Flicker Noise Cancellation

Ifsp,n noise currents are always bypassed to Gm1 OTA or biphasically integrated into Vrw. Gm1 OTA switching.

Feedback DAC

14/22

slide-18
SLIDE 18

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

Flicker Noise Cancellation

Ifsp,n noise currents are always bypassed to Gm1 OTA or biphasically integrated into Vrw. Gm1 OTA switching.

Feedback DAC

qmod = 0

Feedback DAC

14/22

slide-19
SLIDE 19

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

Flicker Noise Cancellation

Ifsp,n noise currents are always bypassed to Gm1 OTA or biphasically integrated into Vrw. Gm1 OTA switching.

Feedback DAC

qmod = 0

Feedback DAC

14/22

slide-20
SLIDE 20

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

Flicker Noise Cancellation

Ifsp,n noise currents are always bypassed to Gm1 OTA or biphasically integrated into Vrw. Gm1 OTA switching.

Feedback DAC

qmod = 0 qmod = 1

Feedback DAC

Feedback DAC

14/22

slide-21
SLIDE 21

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

Flicker Noise Cancellation

Ifsp,n noise currents are always bypassed to Gm1 OTA or biphasically integrated into Vrw. Gm1 OTA switching. qmod = 0 qmod = 1

Feedback DAC Feedback DAC

Feedback DAC

14/22

slide-22
SLIDE 22

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

Flicker Noise Cancellation

Ifsp,n noise currents are always bypassed to Gm1 OTA or biphasically integrated into Vrw. Gm1 OTA switching. qmod = 0 qmod = 1

Feedback DAC Feedback DAC

Feedback DAC

14/22

slide-23
SLIDE 23

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

Flicker Noise Cancellation

qmod = 0 qmod = 1

Feedback DAC Feedback DAC

Optimum cancellation when qmod has equal probability of 1's and 0's quant. symbols (case of very weak chemical signals).

14/22

slide-24
SLIDE 24

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

15/22

1 Amperometric Electrochemical Sensors Conclusions 2 Potentiostatic Modulator architecture 3 4 5 Proposed wide-range potentiostat with 1/f noise cancellation 0.18- CMOS Design and Post-Layout simulations

slide-25
SLIDE 25

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

Electrochemical sensor frontend CMOS layout

480μm x 370μm (0.18mm2). 0.18μm 1P6M CMOS X-FAB technology (XH018). I2C 4-wire bus interface. 1.8-V capless LDO core supply regulator. On-Chip auxiliary modules. Current generator. Vpotp,n programmable sources.

18/22

slide-26
SLIDE 26

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

Post-Layout Simulations

VerilogA: Vrw-Isens DC look-up table based on a Cyclic Voltammetry. 3-Vpp cyclic voltammetry example under 1.8-V voltage supply. Third order Butterworth low-pass filter as digital decimator. 2.5-Hz cutt-off freq. VerilogA.

19/22

slide-27
SLIDE 27

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

Post-Layout Simulations

Output spectrum comparison w/(a) and w/o(b) flicker cancelation technique. Weak input signal -65dBFS

(a) (b)

±100-nA full scale. Sampling freq. 256Hz Bandwidth 1Hz Oversampling ratio 128:

slide-28
SLIDE 28

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

Performance simulation results

21/22

slide-29
SLIDE 29

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

1 Amperometric Electrochemical Sensors Conclusions 2 Potentiostatic Modulator architecture 3 4 5 Proposed wide-range potentiostat with 1/f noise cancellation 0.18- CMOS Design and Post-Layout simulations

slide-30
SLIDE 30

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

Conclusions

22/22

Improved dynamic range (90dB) thanks to Feedback DAC flicker noise cancellation mechanism. Compact architecture (0.18mm2) thanks to the electrode-electrolyte interface used as an integrator stage in the structure. Wide range (±1.5V) potentiostat programmability with minimalist analog circuits fully integrable in purely digital CMOS technologies. High resolution with sub kHz-range sampling frequencies (256Hz).

slide-31
SLIDE 31

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

22/22

I2C plug & play (power and comm.)

Applications and benefits

200μm x 200μm pads First trials of ASIC flip-chip on screen-printed flexible substrates Wearable for chemical sensing in sweat Food quality and safety

slide-32
SLIDE 32

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

Currently being measured...

Thanks for your attention!

slide-33
SLIDE 33

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

Comparison of CMOS Potentiostatic FRONTENDS

slide-34
SLIDE 34

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

Low-power rail-to-rail CMOS circuits

Wide Vrw programmability imposes wide input/output common-mode range for Gm1 and Gm2. Constant gm over the input common-mode voltage:

M3 M4 M1 M2 M5

1 : 1

M1-M4 in weak inversion Sum of tail currents Ibiasp,n constant Sum of tail currents Ibiasp,n constant

16/22

slide-35
SLIDE 35

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

Low-power rail-to-rail CMOS circuits

M3 M4 M1 M2

Wide Vrw programmability imposes challenging input common-mode range for the quantizer. Complementary latched comparators: qoutp,n digitally combined, giving priority to the one still being operational. Zero-static power consumption

17/22

slide-36
SLIDE 36

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

Post-Layout Simulations

Output spectrum for half full-scale input signal -6dBFS. Oversampling ratio 128: ±100-nA full scale. Sampling freq. 256Hz Bandwidth 1Hz

slide-37
SLIDE 37

72- W 90-dB Wide-Range Potentiostatic Modulator

  • J. Aymerich Gubern

5/22

Amperometric Electrochemical Sensors

Cyclic Voltammetry: Different detection methods are required: Most widely used electrochemical technique. Chronoamperometry: Wide sweeping potentials Rapid location of the redox potentials.

0.7 0.0 0.1 0.2 0.3 0.4 0.5 0.6

t [s]

1

[A]

  • 1
  • 1

1 1

  • 1

1

Vrw stepped and Isens monitored as a function of time.

[A]

1

t [s]

1