Kenji Kogo

Direct measurement of chirp parameters of high-speed Mach-Zehnder-type optical modulators

Abstract A method is described for measuring the chirp parameters and optical responses of Mach–Zehnder-type optical modulators by using an optical spectrum analyzer. The chirp parameter and the optical response for small-signal operation are expressed by the magnitude of the phase induced in each optical path of the Mach–Zehnder waveguides. The induced phase can be obtained from the ratio of the high-order optical harmonic intensities generated by large-signal operation in the millimeter-wave region. This method permits the chirp parameter to be evaluated at a specific frequency, while it is assumed to be independent of the frequency of the applied electric rf signal in the conventional method.

Contactless Liquid-Level Measurement With Frequency-Modulated Millimeter Wave Through Opaque Container

A novel contactless method for measuring liquid level through an opaque container is proposed. A millimeter-wave Doppler sensor is developed to “see” (i.e., sense) through a target container and measure the liquid level on the basis of the absorption of millimeter waves in liquid. One of the challenges is to accurately measure liquid level (within sub-millimeter error) despite the inherently large beam diameter of the millimeter wave due to diffraction. A piezoelectric vibrator enables accurate measurement by reflecting a limited portion of the spread beam and modulating it in frequency to distinguish it from the other portion of the beam. A prototype measurement system is fabricated and evaluated. The feasibility of our proposed method for clearly detecting an air-liquid interface concealed in an opaque container is confirmed experimentally. The nonlinearity error of the measured liquid level is within ±0.5 mm .

A 25-Gb/s 2.2-W optical transceiver using an analog FE tolerant to power supply noise and redundant data format conversion in 65-nm CMOS

A one-chip transceiver was developed for optical backplanes by integrating an analog FE with data format conversion in 65-nm CMOS. 10×6.25Gb/s electrical signals were converted to 4×25Gb/s optical signals with 25% redundancy to improve resilience against possible LD failure. To alleviate degradation of the optical link due to power-supply variations, a TIA with a noise canceller and a fully differential LDD are proposed. The noise canceller decreases power-supply variations by 98%. Total power consumption was only 2.2W.

25-Gb/s 100-m MMF Transmission Using a Prototype 1.3-

A prototype transceiver composed of a 1.3-μm-range lens-integrated laser diode and photodiode as well as a complementary metal-oxide-semiconductor (CMOS) laser diode driver and a CMOS transimpedance amplifier for high-speed optical interconnections was developed. It demonstrated 25-Gb/s error-free 100-m multimode fiber transmission, with power dissipation of only 9 mW/Gb/s, for the first time.

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A compact 25-Gbps × 4-channel optical transceiver has been fabricated for optical backplane systems. Power consumption was as low as 20 mW/Gbps. A transmission experiment was successfully conducted at 25 Gbps.

-Range CMOS-Based Transceiver for Optical Interconnections

A new 77 GHz single-chip radar sensor has been developed, which encapsulates a GaAs p-HEMT transceiver MMIC with an on-chip patch antenna in a resin-molded package integrated with a resin collimating lens on the top to achieve an EIRP of 13.5 dBm and a receiving gain of 8 dB. The packaged sensor, measuring 6.5times4.4times6.0 mm3 with only DC and baseband- frequency leads, offers ease of handling with an extreme low-cost potential for a variety of applications. When adopted to an automotive ground speedometer integrated with an signal processing unit, the sensor demonstrated accurate and reliable detections of vehicle speed with a standard deviation of 1.5% under normal driving conditions.

100-Gbps CMOS transceiver for multilane optical backplane system with a 1.3 cm 2 footprint

The amount of data traffic is increasing year by year as the number of data-rich services like cloud services and streaming services are increasing. The number of switch modules between servers should decrease to lower latency, and several servers in each rack should be connected to one switch module with cables in a data centre. Using copper cables to connect racks is attractive in terms of cost minimization. Thin cables, for example 34 AWG copper cables, make maintenance easy. The cable length should be 5-7m to connect between racks, and 34 AWG 7m cable has 48dB loss, including board trace loss, package loss and so on. So far transceivers over 25Gb/s, equalizing 35-40dB channel loss have been proposed [1-4], with which low-loss cables like 26 AWG have been required. We target a 25Gb/s transceiver equalizing over 50dB channel loss, and adopt a sub-mV dynamic DC offset cancelation and a decision-feedback equalizer (DFE) with a bias-controlled tap slicer. Both improve on the minimum input sensitivity and enable data transmission through a channel with over 50dB loss.

77GHz Low-Cost Single-Chip Radar Sensor for Automotive Ground Speed Detection

We demonstrate a high-speed waveguide photo-diode that has high responsivity when butt-coupled to a flat-ended single-mode fiber. An extremely thin lens-less surface-mountable 10-Gbps receiver module with this photodiode installed has a high responsivity (0.97 A/W) and high sensitivity (-18.8 dBm).

3.3 A 25Gb/s multistandard serial link transceiver for 50dB-loss copper cable in 28nm CMOS

We developed a long channel backplane 28 Gbps transmission technology for next-generation high-speed I/O applications. To achieve long-channel backplane traces at 28 Gbps, main jitter sources such as ISI, crosstalk, power supply noise, and circuit origin including random jitter need to be drastically reduced. Among these, ISI is the largest jitter source. It is important to not only compensate for loss of channel but also reduce reflections due to impedance mismatch. Therefore, we proposed a low-jitter implementation technology for a package (PKG) and a print circuit board (PCB). This technique is a method to buffer the impedance mismatch by the impedance drop of a solder ball at high-speed transmission. By using the proposed technique, the ISI jitter can reduce 1 ps and EYE opening margin can be made larger than 0.04 UI.

Highly efficient lens-less coupling of high-speed waveguide photodiode to SMF and its application to an extremely thin surface-mountable 10-Gbps receiver module

A transceiver for a 25.8Gbps/lane with a re-timer IC has been developed for information and communication equipment. Since a 1-unit interval (UI) is very narrow at 38.8 ps at 25.8Gbps, power integrity (PI) jitter due to power supply fluctuation cannot be ignored. In this paper, we proposed a decoupling-capacitors (Decaps) placement technique to reduce power distribution network impedance (Zpdn) and a circuit design procedure regarding power supply fluctuation. The re-timer IC adopted from the proposed procedure achieved a bit error rate (BER) lower than 1 × 10−12 on backplane transmission with an insertion loss (IL) of 40 dB.