Kandou Technologies

Chord Signaling

We invented Chord Signaling, a multi-wire signaling approach that is a generalization of differential signaling. Our research programs have systematically explored several hundred different signaling techniques, including traditional ones.

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Forward Error Correction

We have deep expertise in the development of FEC algorithms and blocks. FEC is a key enabler of high-performance links.

Analog, Mixed-Signal and SerDes Design

We have an expert team of analog and mixed-signal designers who have superior expertise bringing complex, high-rate semiconductor devices to mass production that feature Serializer/Deserializer (SerDes) and Phase Locked Loop (PLL), and clocking circuits. This capability is increasingly rare in the semiconductor industry.

Repeater System Technology

We have a systems understanding of repeater technology, which is a core enabler for robustly extending the reach of high-performance links.

Applications of Chord Signaling

Long Reach Links

Chord Signaling delivers links with better signal integrity and lower power consumption versus links that use only differential techniques such as PAM-4. For example, our ENRZ modulation technique delivers NRZ-like Inter-Symbol Interference (ISI) performance while avoiding PAM-4's need for power-hungry precise equalization. ENRZ has been standardized by the Optical Internetworking Forum (OIF) as OIF-CEI-56G-LR-ENRZ.

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Memory Links

Two Chord Signaling techniques have been adopted by JEDEC's physical layer group JC-16. Two potential uses of Chord Signaling in memory links are to notably extend the bandwidth of serial memory modules with an ENRZ interface, and the reach of High Bandwidth Memory (HBM) interfaces with a half-duplex version of our CNRZ-5 interface.

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System in Package Links

As exemplified by our shipping Glasswing interface product, Chord Signaling is ideal for supporting very high bandwidth interfaces within a package using low-cost organic package substrates. Other solutions require expensive and yield-reducing silicon interposer manufacturing technology. Our Glasswing's CNRZ-5 code delivers more bits with lower power than competing solutions.

Extending the Life of Copper

The media has been reporting the impending death of high-rate copper interfaces over the last few years as the bandwidth requirement continues to increase. Our solutions using advanced modulation techniques can extend the lifetime of copper interfaces, which in turn reduces power, cost, and development time.

Tools to Explore Chord Signaling


KEYE is our in-house developed, GUI-based statistical eye simulator that includes support for various Chord Signaling techniques including ENRZ and CNRZ-5. It is ideal for exploring the interaction between transceivers and channels


TAU is our in-house developed, GUI-based time-domain SerDes modeling tool. It is perfect for investigating the behavior of adaptation loops on transceivers. Its implementation supports short and fast simulation times for a time-based simulator.