We present a Discrete Cosine Transform (DCT) unit embedded with Error Detection Sequential (EDS) and Dynamic Voltage Scaling (DVS) circuits to speculatively monitor its noncritical datapaths. This monitoring strategy requires no buffer insertions with only minimal modifications to the existing digital design methodology and is therefore applicable for Field-Programmable Gate Array (FPGA) implementations. The proposed design is implemented in an FPGA. The duty cycles of the constraint clock and the actual clock are differentiated to guide the synthesizer to place the EDS circuits with specific timing margin. The proposed design is tested with two classic images and is able to detect timing errors in the noncritical datapaths due to dynamic process, voltage and temperature (PVT) variations. The DVS circuit correspondingly controls a linear voltage regulator to adjust the supply voltage to the Point of First Failure (PoFF). No actual timing errors are generated, primarily because of the unique speculative characteristic of the proposed monitoring strategy. Our proposed design incurs a 0.3% logic element overhead and 3.5% maximum frequency degradation. By lowering the supply voltage by 8.3%, the proposed design saves up to 16.5% energy when operating at the same frequency as a highly optimized baseline DCT implementation.

With a specified Mean Timing Between Failure (MTBF), the metastability resolution time of synchronizers possibly constrains the system performance. To enhance metastability resolution time under single low-voltage supply environments, Voltage-Boosted Synchronizers (VBSs) consisting of a basic minimum-sized Jamb latch and a switched-capacitor-based charge pump are proposed. The capacitor of the charge pump is sized 13 times the area of the Jamb latch. Two powering strategies of the charge pump, namely Metastability-driven VBS (MVBS) and Clock-driven VBS (CVBS), are proposed. For a 1-year MTBF specification, MVBS and CVBS show 2.0-2.7 and 5.1-9.8 times the performance improvement over the basic Jamb latch, respectively, without incurring large power consumption.