ECOLogic: Hybrid ASIC-eFPGA SoC Design

• ECOLogic is a hybrid System-on-Chip design paradigm that integrates static ASIC and selective eFPGA regions to achieve circularity, obfuscation, and adaptivity.
• It employs ECOScore, a quantitative framework weighing adaptability, piracy threat, performance tolerance, and resource fit to selectively partition RTL blocks.
• ECOLogic demonstrates ~90% ASIC performance with orders-of-magnitude power savings and a dramatically lower carbon footprint compared to FPGA-only approaches.

ECOLogic is a hybrid System-on-Chip design paradigm that embeds lightweight embedded FPGA (eFPGA) fabric within ASICs to provide circular, obfuscated, and adaptive logic. It is presented as a response to the conventional ASIC–FPGA trade-off: ASICs provide high efficiency but are inflexible post-fabrication, require costly re-spins for updates, and expose IPs to piracy risks, whereas FPGAs offer reconfigurability and reuse but incur substantial area, power, and performance overheads with higher carbon footprints. ECOLogic combines a static ASIC region with a selectively reconfigurable eFPGA region, and uses a quantitative partitioning framework, ECOScore, to decide which RTL blocks should remain hardened and which should be mapped into reconfigurable fabric (Tashdid et al., 6 Aug 2025).

1. Design problem and conceptual scope

ECOLogic is defined around three objectives. The first is circularity, meaning reuse, repurpose, repair, and remanufacture rather than a conventional build-use-discard lifecycle. The second is obfuscation, achieved by eFPGA-based logic redaction that hides sensitive IPs until post-fabrication configuration. The third is adaptivity, meaning post-fabrication updates, hardware reuse, and logic remapping without full re-spins or chip replacement (Tashdid et al., 6 Aug 2025).

The design problem addressed by ECOLogic is not generic reconfigurability in the abstract, but selective reconfigurability under performance, security, and sustainability constraints. In this formulation, stable IPs such as general-purpose cores, interconnects, and system controllers remain in a hardened ASIC region, while update-prone or sensitive logic is assigned to an eFPGA region. The paper characterizes this as a way to bridge the gap between ASIC-class efficiency and FPGA-like updatability while incorporating security and lifecycle circularity into the same design framework (Tashdid et al., 6 Aug 2025).

2. eFPGA-augmented SoC architecture

The physical organization of an ECOLogic SoC is split into two regions: a static ASIC region and an eFPGA region. The ASIC region is intended for hardened, high-performance, and stable IPs. The eFPGA region is described as tile-based arrays of Configurable Logic Blocks containing LUTs, flip-flops, multiplexers, and switch blocks. Communication is supported across an AXI bus, configuration is bitstream-driven through frame-based or scan-chain mechanisms, and runtime updates are performed via secure protocols. The summarized implementation flow references open-source synthesis support through Yosys and FABulous (Tashdid et al., 6 Aug 2025).

This organization is meant to localize flexibility rather than distribute it uniformly across the chip. Sensitive or frequently changing logic can be redacted into the eFPGA fabric, so functionality is only revealed after secure configuration. The same structure also supports dynamic, in-field security monitoring and policy enforcement, as well as runtime remapping to healthy regions under aging or thermal stress. A plausible implication is that ECOLogic treats reconfigurable fabric as a strategic resource, not as a wholesale substitute for hardened logic.

3. ECOScore and RTL partitioning

At the methodological center of ECOLogic is ECOScore, a quantitative framework for RTL-level partitioning. It evaluates IP blocks using four weighted factors: adaptability, piracy threat, performance tolerance, and resource fit. These factors are combined into a composite score used to rank which IPs should migrate to eFPGA fabric and which should remain in the ASIC region (Tashdid et al., 6 Aug 2025).

For an IP $i$, the summarized formulation defines adaptability as

$$A_i = \frac{\ln(1 + \mathrm{LOC\_changed}_i)}{\ln(1 + \max_j \mathrm{LOC\_changed}_j)}$$

so that frequent RTL change favors eFPGA placement. Piracy threat is expressed as

$$O_i = \mu C_i + \nu E_i + \xi R_i,\qquad \mu + \nu + \xi = 1$$

with exposure given by

$$E_i = \frac{\# I/O + \text{control nets}}{\# \text{internal nets} + \text{state elements}}$$

and the redaction ratio defined as

$$R_i = \frac{\text{logic mapped to eFPGA}}{\text{total logic in IP}}.$$

Performance tolerance measures frequency loss under eFPGA implementation:

$$P_i = 1 - \min\left(1, \frac{F^{\text{ASIC}}_{\max,i} - F^{\text{eFPGA}}_{\max,i}}{F^{\text{ASIC}}_{\max,i}}\right).$$

Resource fit is defined as a normalized area-cost term:

$R_i = \frac{A_{\max} - A_i}{A_{\max} - A_{\min}}.$

The final composite score is

$$\mathrm{ECOScore}_i = \alpha A_i + \beta O_i + \gamma P_i + \delta R_i, \qquad \alpha + \beta + \gamma + \delta = 1.$$

In the reported evaluation, ASCON and SHA-256 obtain ECOScore values of $0.86$ and $0.84$, Transformer and CNN designs obtain $$A_i = \frac{\ln(1 + \mathrm{LOC\_changed}_i)}{\ln(1 + \max_j \mathrm{LOC\_changed}_j)}$$0 and $$A_i = \frac{\ln(1 + \mathrm{LOC\_changed}_i)}{\ln(1 + \max_j \mathrm{LOC\_changed}_j)}$$1, and the CVA6 interconnect and controller obtain $$A_i = \frac{\ln(1 + \mathrm{LOC\_changed}_i)}{\ln(1 + \max_j \mathrm{LOC\_changed}_j)}$$2 and $$A_i = \frac{\ln(1 + \mathrm{LOC\_changed}_i)}{\ln(1 + \max_j \mathrm{LOC\_changed}_j)}$$3. The reported rankings place AI accelerators and cryptographic cores at the top for adaptability and security reasons, while stable control logic and interconnects favor the ASIC region. This suggests that ECOScore is intended to operationalize selective rather than uniform migration into reconfigurable fabric (Tashdid et al., 6 Aug 2025).

4. Reported performance, timing, and power characteristics

ECOLogic is evaluated across six SoC modules. The paper reports that the design retains an average of 90 percent of ASIC-level performance, and the detailed summary states that maximum clock frequency reaches up to 2.2 GHz across benchmark designs. For a CNN accelerator, ECOLogic is reported at 2.2 GHz versus 2.53 GHz for ASIC and 0.125 GHz for FPGA (Tashdid et al., 6 Aug 2025).

Timing behavior is presented as one of the main advantages over FPGA-only realization. ECOLogic achieves 9.8 ns timing slack, compared with 5.1 ns in FPGA. Under thermal stress, the paper reports that at $$A_i = \frac{\ln(1 + \mathrm{LOC\_changed}_i)}{\ln(1 + \max_j \mathrm{LOC\_changed}_j)}$$4, ECOLogic retains more than 5 ns slack, versus less than 2 ns for ASIC, by remapping logic within the fabric to healthy regions. The interpretation offered in the summary is that runtime logic remapping provides timing resilience under aging and temperature variation (Tashdid et al., 6 Aug 2025).

Power results are reported as orders-of-magnitude lower than FPGA. ECOLogic is described as consuming approximately 52 mW versus 25,000 mW for traditional FPGAs, corresponding to an average 480 times reduction. The paper’s performance claim is therefore not based on raw frequency alone, but on the combined observation that selective reconfigurability preserves much of ASIC performance while avoiding the large power and slack penalties associated with FPGA-only deployment (Tashdid et al., 6 Aug 2025).

5. Security, circularity, and carbon footprint

Security in ECOLogic is tied to logic redaction, post-fabrication configuration, and in-field security patching. Sensitive IP is physically hidden until programmed at deployment, and the fabric supports dynamic, in-field security monitoring and policy enforcement. In this formulation, obfuscation is not an add-on to the architecture; it is one of the explicit drivers of partitioning through ECOScore’s piracy-threat component (Tashdid et al., 6 Aug 2025).

Circularity is expressed as a lifecycle model in which hardware is fabricated once and updated through reconfiguration rather than replaced. The summarized paper contrasts this with traditional build-use-discard ASIC or FPGA processes and emphasizes reuse, repair, repurpose, and remanufacture. A plausible implication is that ECOLogic treats hardware longevity as a design objective at the architecture level rather than as a secondary operational benefit.

The sustainability results are reported in quantitative terms. ECOLogic achieves a 99.7 percent lower deployment carbon footprint than FPGA implementations and 300–500 times lower emissions relative to FPGA-only implementations. For cryptographic and AI cores in a one-year deployment comparison, ECOLogic is reported at $$A_i = \frac{\ln(1 + \mathrm{LOC\_changed}_i)}{\ln(1 + \max_j \mathrm{LOC\_changed}_j)}$$5 kg CO$$A_i = \frac{\ln(1 + \mathrm{LOC\_changed}_i)}{\ln(1 + \max_j \mathrm{LOC\_changed}_j)}$$6 versus $$A_i = \frac{\ln(1 + \mathrm{LOC\_changed}_i)}{\ln(1 + \max_j \mathrm{LOC\_changed}_j)}$$7 kg CO$$A_i = \frac{\ln(1 + \mathrm{LOC\_changed}_i)}{\ln(1 + \max_j \mathrm{LOC\_changed}_j)}$$8 for FPGA. The deployment-phase expression is summarized as

$$A_i = \frac{\ln(1 + \mathrm{LOC\_changed}_i)}{\ln(1 + \max_j \mathrm{LOC\_changed}_j)}$$9

where runtime and deployment-related carbon are aggregated across applications (Tashdid et al., 6 Aug 2025).

6. Position relative to ASIC and FPGA design styles

The paper positions ECOLogic as neither a conventional ASIC nor a conventional FPGA, but as a selective hybrid intended to preserve the strengths of both while reducing their liabilities. The comparison reported in the summary is structured around performance, flexibility, power, security, carbon footprint, lifetime, and reliability (Tashdid et al., 6 Aug 2025).

Aspect	ASIC / FPGA baseline	ECOLogic
Performance	ASIC best; FPGA 8–16x slower than ASIC	~90% of ASIC, 16x better than FPGA
Flexibility	ASIC none after fab; FPGA reconfigurable with high overhead	Selective reconfig, low overhead
Power	ASIC lowest; FPGA very high	ASIC-like, 480x lower than FPGA
Security	ASIC exposed at foundry; FPGA bitstream can be attacked	eFPGA redaction + bitstream, post-fab patch
Carbon footprint	ASIC high for re-spins; FPGA high for area/power	Lowest, with reuse, circularity, and partial configuration
Reliability and lifetime	ASIC fixed/obsolete; FPGA more updatable but with overhead	Extended by in-field hardware updates and dynamic remapping

A recurrent misconception in discussions of hybrid reconfigurable hardware is that such systems are simply reduced-size FPGAs embedded beside processors. ECOLogic is described more narrowly and more systematically than that. Its core claim is that the architecture becomes effective only when reconfigurable capacity is guided by ECOScore and allocated to the IPs with the strongest combination of adaptability, piracy threat, performance tolerance, and resource fit. The paper therefore presents ECOLogic not merely as an implementation template, but as a design methodology that, in its own framing, is the first to systematically quantify and optimize security, adaptability, and sustainability in hybrid SoC design via the ECOScore framework (Tashdid et al., 6 Aug 2025).