Escalator Network for a 3D Chip Stack with Inductive Coupling ThruChip Interface

Abstract

A wireless inductive coupling ThruChip Interface (TCI) is a flexible system-in-package (SiP) technique which enables to build a powerful interconnection network between stacked chips. For easy use of TCI, we have developed intellectual properties (IPs), and proposed an interconnection network which can make the use of IPs. We also developed a real chip embedded the IP, and evaluated the performance. By stacking multiple chips with the proposed IP, an inter-chip network with link-to-link flow control by piggyback control is established. The new proposed escalator network which uses piggyback of the credit packets outperforms the ring network used in the first prototype by 28%-59% in terms of throughput. The performance overhead by the piggyback control was less than 3%-4% of that without control messages.

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

“…The router layer is parameterized and can generate routers with any number of inputs and outputs, each equipped with eight virtual channels. Stacking chips using this IP can build a linear bidirectional (escalator) network [15]. The hard IP includes inductors for clock transfer and data transfer, respective transceiver circuits, and a SERDES circuit for data.…”

“…This entire process takes a total of 66 clock cycles, resulting in a digital transfer frequency of 1/66 of TxCLK. By stacking a group of chips equipped with the set of four TCI IPs as described above, with the upper chip's DT aligned with the lower chip's UR, and the upper chip's DR aligned with the lower chip's UT in the vertical direction, a data communication mechanism is established in the upward direction (UT→DR) and downward direction (UT→DR), creating a bidirectional linear network [15] (Figure 5). Additionally, the intermediate chip in the stack can have one side exposed on the surface, allowing for bonding.…”

3D system-on-a-chip design with through-silicon-via-less power supply using highly doped silicon via

“…As for data communications between 3D-stacked chips, the ThruChip Interface (TCI), which uses inductive coupling, was developed. [12][13][14][15][16][17][18][19][20][21][22] Since TCI utilizes on-chip coils implemented as part of the backend-of-line process, it maintains the conventional wafer logistics and is low-cost. Furthermore, TCI has reportedly achieved higher area efficiency and lower power dissipation than TSV does.…”