A 12 μW 10 kHz BW 58.9 dB SNDR AC-Coupled Incremental ADC for Neural Recording

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper proposes a neural recording circuit by using AC-coupling incremental ADC and shows the research results of actual implementation.

However, I hope that some of the changes below can be reflected.

1. Compared to other recent studies, the input dynamic range or SNDR is relatively small. Usually, the input dynamic range is represented more than 10 times wider than 24mVpp to eliminate stimulation artifacts. Can you explain further on this point?

2. INL and DNL seem to be measured relatively high. I think further explanation is needed on this.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The authors present an AC-coupled ADC for recording of neural activity. The paper is well organized, but the English language needs to be improved. I have some major concerns regarding the originality of this work. I would appreciate if the authors could highlight the difference between their work and [29], apart from the ac coupling. 
Moreover, I didn't understand why the choice to not chop the input pair of the OTA, since it is the most relevant. For the same reason, I don't understand why, for the DAC, no chopping technique is employed, but the authors rely only on increasing area, which is a majorn concern of this design. Furthermore, it is not clear why the Chop_P switches are turned of during the coarse quantization. Are there any countereffects that are not present during the fine quantization? What about the rejection of the chopper artifacts (like offset ripple)? Is it included in the digital filter? Please specify.

The details about the design of current reference are not so interesting, since the topology is quite standard and the noise minimization strategy is standard as well.

Do the author know the source of the low frequency noise present in the spectra of Fig.14-15? Does it come from the input differential pair or the DAC? What would be the nominal resolution of the ADC?

I suggest the authors to provide also the Figure of Merits of their ADC in order to better compare it with other state-of-art works. Is the frequency range of the RTI noise 1-10 kHz or 1 Hz- 10 kHz?

 

Comments on the Quality of English Language

English language needs to be improved. Please doublecheck the whole manuscript.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The paper describes a AC-Coupled Incremental ADC for Neural Recording.

The manuscript is well written and shows the advantage of having the ADC only for neural recording. The measurements results demonstrate the idea and the performance comparison with the state-of-the-art is very good.

 

The manuscript however need to have some improvements.

1 - Statement 58 is repeated.

2 – Please provide the THD for different frequency, and for low frequency more close to the signal normal bandwidth, 10Hz. Fig. 15 only shows results for 1kHz.

3 – What is the ENOB for low frequency. Please include it on paper.

4 – The accuracy of the pseudo-resistor should not be very good based on the tech data. Please provide the experimental low frequency response of the circuit.

Comments on the Quality of English Language

- Statement 58 is repeated.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

I appreciate the effort spent by the Authors to reply to my comments and the improvements made on the manuscript.

Comments on the Quality of English Language

Please doublecheck the whole manuscript.