Publication # 226

C. Debaes, D. Agarwal, A. Bhatnagar, H. Thienpont, and D. A. B. Miller, "High-Impedance High-Frequency Silicon Detector Response for Precise Receiverless Optical Clock Injection," in SPIE Photonics West 2002 Meeting, San Jose, California, Proc. SPIE Vol. 4654, 78-88 (2002)

We report the direct injection of precise clock signals into standard CMOS circuits using short optical pulses by a novel receiverless scheme that eliminates the delay, skew and jitter of a typical receiver. To accomplish the optical injection we designed small silicon detectors along-side standard 0.25 micron CMOS circuits. Due to the low intrinsic capacitance of the detectors, the photogenerated carriers can directly generate voltage swings that are comparable with CMOS voltage levels if the detectors are loaded with high-impedance circuits.

As a first step to implement this scheme we characterized various detectors built in the CMOS process for their high-frequency response. In a test set-up the silicon detectors are sampled with on-chip samplers that only present a small capacitive loading to the detector node. we present the high-frequency high-impedance response measured with this scheme together with capacitance measurements and DC responsivities of various types and sizes of detectors. The characterized long tails typically observed with silicon detectors allowed us to set up a model for the power penalty we have to take  into account for precise clock detection.

Finally, as a proof-of-principle demonstration we present the first results of this receiverless scheme in which a totem-pole of silicon detectors directly drives an on-chip CMOS inverter.

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