Review Reports - TCI Tester: A Chip Tester for Inductive Coupling Wireless Through-Chip Interface

Round 1

Reviewer 1 Report

The authors propose an IP for testing wireless and inductive data coupling among SoCs. The following comments must be addressed:

1. A proper figure showing the IP/chip under test relative to the proposed tester IP needs to be presented.

2. Is the proposed testing IP applicable to multiple data communication IPs under test? This is not clear in the paper. What is the range of frequencies and other characteristics of the SoC to be testable by this tester? A detailed description of the SoCs testable by this IP is needed.

3. A detailed figure of the Tester IP with block diagram and data flow between them is necessary.

4. The tester IP needs to be compared with existing testing methods for establishing performance with respect to the state of the art.

5. References need to be improved as there is a rich literature in wireless chip-to-chip communication transceiver among SoCs.

none.

Author Response

Point 1: A proper figure showing the IP/chip under test relative to the proposed tester IP needs to be presented.

Response 1: Thank you for the comment. We have added Fig.7 to show how the TCI Tester is stacked on the test target chip.

Point 2: Is the proposed testing IP applicable to multiple data communication IPs under test? This is not clear in the paper. What is the range of frequencies and other characteristics of the SoC to be testable by this tester? A detailed description of the SoCs testable by this IP is needed.

Response 2: Thank you for the comment. We were not sure we could get the correct meaning of "multiple data communication IPs", but it is possible if it means the IP for sending data to/from multiple IPs placed in the same position vertically. Usually, such IPs for TCI buses use large coils, and TCI Tester can be stacked on the exact center of the coil to detect inductive waves.

The TCI Tester was implemented with Renesas 65nm CMOS SOTB process and applicable chips with similar processes. Although CUBE and LOOP modes are only applicable to the IPs with the same data transfer protocol, RAW mode can detect inductive waves. The operational frequency is up to 2 GHz, as shown in Fig.13. We added the description in Section 3.1.

Point 3: A detailed figure of the Tester IP with block diagram and data flow between them is necessary.

Response 3: The detailed circuits of the Tester IP are shown in Fig.2, the timing chart in Fig.3, the block diagram in Fig.8, and data flows in Fig.9 and Fig.10, respectively.
The reason why the reviewers felt that a new figure was necessary is probably because the existing figures were distantly located and did not clearly explain how these figures explain the proposed IP. Therefore, we have added a sentence summarizing and explaining which parts of IP these figures are describing.

Point 4: The tester IP needs to be compared with existing testing methods for establishing performance with respect to the state of the art.

Response 4: Although circuit-level TCI test methods have been investigated[12], chip-level test method has not been tried. This is our motivation to develop TCI Tester.

[12] Yoshida, Y.; Nose, K.; Nakagawa, Y.; Noguchi, K.; Morita, Y.; Tago, M.; Kuroda, T.; Mizuno, M. Wireless DC voltage transmission using inductive-coupling channel for highly-parallel wafer-level testing. In Proceedings of the 2009 IEEE International Solid-State Circuits Conference-Digest of Technical Papers. IEEE, 2009, pp. 470–471.

Point 5: References need to be improved as there is a rich literature in wireless chip-to-chip communication transceiver among SoCs.

Response 5: We added some references below:

[1] Lee, C.; Park, J.; Park, C. Zigzag-shaped coil array structure for wireless chip-to-chip communication applications. IEEE Transactions on Electron Devices 2014, 61, 3245–3251.

[2] Sun, X.; Pantano, N.; Kim, S.W.; Van der Plas, G.; Beyne, E. Inductive links for 3D stacked chip-to-chip communication. In Proceedings of the 2019 IEEE 69th Electronic Components and Technology Conference (ECTC). IEEE, 2019, pp. 1215–1220.

[3] Mizoguchi, D.; Yusof, Y.B.; Miura, N.; Sakura, T.; Kuroda, T. A 1.2 Gb/s/pin wireless superconnect based on inductive inter-chip signaling (IIS). In Proceedings of the 2004 IEEE International Solid-State Circuits Conference (IEEE Cat. No. 04CH37519). IEEE, 2004, pp. 142–517.

[4] Kim, Y.; Tam, S.W.; Chang, M.C.F. Millimeter-wave contactless connectors: From fundamental research to commercialization. IEEE Microwave Magazine 2022, 23, 55–70.

[5] Lee, C.J.; Kim, S.H.; Son, H.S.; Kang, D.M.; Kim, J.H.; Byeon, C.W.; Park, C.S. A 120 GHz I/Q transmitter front-end in a 40 nm CMOS for wireless chip to chip communication. In Proceedings of the 2018 IEEE Radio Frequency Integrated Circuits Symposium (RFIC). IEEE, 2018, pp. 192–195.

[6] Kuroda, T. ThruChip Interface (TCI) for 3D Networks on Chip. In Proceedings of the 2011 IEEE/IFIP 19th International Conference on VLSI and System-on-Chip, 2011, pp. 238–241.

[7] Shiba, K.; Okada, M.; Kosuge, A.; Hamada, M.; Kuroda, T. A 12.8-Gb/s 0.5-pJ/b Encoding-Less Inductive Coupling Interface Achieving 111-GB/s/W 3D-Stacked SRAM in 7-nm FinFET. IEEE Solid-State Circuits Letters 2023, 6, 65–68.

[8] Kosuge, A.; Kuroda, T. Proximity Wireless Communication Technologies: An Overview and Design Guidelines. IEEE Transactions on Circuits and Systems I: Regular Papers 2022, 69, 4317–4330. https://doi.org/10.1109/TCSI.2022.3210200.

[9] Shiba, K.; Okada, M.; Kosuge, A.; Hamada, M.; Kuroda, T. A 7-nm FinFET 1.2-TB/s/mm 2 3D-Stacked SRAM with an Inductive Coupling Interface Using Over-SRAM Coils and Manchester-Encoded Synchronous Transceivers. In Proceedings of the 2022 IEEE Hot Chips 34 Symposium (HCS). IEEE, 2022, pp. 1–14.

Reviewer 2 Report

Dear Authors,

Congratulations on this paper, in which it is developed a verification chip teste that allows the evaluation of the characteristics of the TCI IP by stacking it on the 40 TCI-equipped chips. The results are promising and highlight that the data transfer process in the experiments made depends on the voltage of the power supply and the operational frequency.

Some suggestions I add here:

Title: It could be better worded to indicate more clearly the objective of the paper.

Keywords: The words “Inductive Wireless inter-chip channel” and ”3D-stacked LSI” are not frequently words used in the paper title, abstract or text; Meaningful words should be proposed for this work.

Text:

r.32-36 - It is not clear whether the research is done by the authors cited or by the authors of this article; The sentence should be rephrased.

r.81, r.83, etc.r.244 - For physical/geometric/ quantities: a gap must be left between value and unit of measurement; The unit d measure should not be italicized (example: 240 µm; 0.75 V).

r.222 – 80 μm

r.374 – The conclusions should be more detailed to synthetically include the multitude of researches conducted.

Author Response

Point 1:

Some suggestions I add here:

Title: It could be better worded to indicate more clearly the objective of the paper.

Response 1: According to the reviewer’s comments, we changed the title "TCI Tester: A Characteristic Measurement Chip for Inductive Coupling Through-Chip Interface" to "TCI Tester: A Chip Tester for Inductive Coupling Wireless Through-Chip Interface". And we changed the keywords "Inductive Wireless inter-chip channel; Through Chip Interface; 3D-stacked LSI" to "Inductive coupling; Inter-chip wireless communication; Through Chip Interface; three-dimensional LSI stacking"

Point 2:

Text:

r.32-36 - It is not clear whether the research is done by the authors cited or by the authors of this article; The sentence should be rephrased.

r.81, r.83, etc.r.244 - For physical/geometric/ quantities: a gap must be left between value and unit of measurement; The unit d measure should not be italicized (example: 240 µm; 0.75 V).

r.222 – 80 μm

r.374 – The conclusions should be more detailed to synthetically include the multitude of researches conducted.

12th-line, left column in p.7:

Response 2: We corrected sentences according to the reviewer's comments. Thanks a lot.