A digitally controlled threshold adjustment circuit in a 0.13um SiGe BiCMOS technology for receiving multilevel signals up to 80Gbps

In this paper, a high bandwidth digitally controlled threshold adjustment circuit is proposed which can be used for demodulating high-speed multi-level signals. Simulations of the bandwidth are presented together with measurements of the control currents to indicate the threshold adjustment capability. A bandwidth above 80GHz in a 0.13µm SiGe BiCMOS technology and a threshold tunable between ±160mV in steps of 0.6mV is achieved, allowing very precise control of the threshold level. This allows the circuit to accurately position the threshold on the eye-crossing of a high speed multi-level signals. By applying this circuit to demodulate a duobinary signal over a 40GHz channel, a data rate of up to 80Gbps can be achieved

56+ Gb/s serial transmission using duo-binary signaling

In this paper we present duobinary signaling as an alternative for signaling schemes like PAM4 and Ensemble NRZ that are currently being considered as ways to achieve data rates of 56 Gb/s over copper. At the system level, the design includes a custom transceiver ASIC. The transmitter is capable of equalizing 56 Gb/s non-return to zero (NRZ) signals into a duobinary response at the output of the channel. The receiver includes dedicated hardware to decode the duobinary signal. This transceiver is used to demonstrate error-free transmission for different PCB channel lengths including a state-of-the-art Megtron 6 backplane demonstrator

DSP-free and real-time NRZ transmission of 50Gb/s over 15km SSMF and 64Gb/s back-to-back with a 1.3um VCSEL

We demonstrate and analyze 50 Gb/s non-return-to-zero (NRZ) transmission over 15 km of standard single-mode fiber (SSMF), 60-Gb/s NRZ transmission over 5 km of SSMF and up to 64-Gb/s NRZ back-to-back using a directly modulated short-cavity long-wavelength single-mode vertical-cavity surface-emitting laser (VCSEL) emitting at 1326 nm. Owing to an analog 6-tap transmit feedforward equalizer, the link can operate without digital signal processing. In all three cases, real-time bit error ratio measurements below the 7% overhead hard-decision forward error correction threshold are demonstrated when transmitting a pseudorandom bit sequence with a period of 2(7) - 1 bits. In addition, we analyze the interplay between the residual fiber chromatic dispersion at the operating wavelength of the VCSEL and the chirp due to direct modulation. These results demonstrate how O-band, short-cavity long-wavelength single-mode VCSELs can be used in intradata center networks, as well as in interdata center networks at reaches below 15 km

Measurements of millimeter wave test structures for high speed chip testing

This paper presents the frequency domain characterization of very high bandwidth connectorized traces and a millimeter wave rat race coupler. These connectorized differential grounded coplanar waveguide traces, essential for the testability of high speed integrated circuits, have a measured flat frequency response up to 67GHz which indicates correct connector footprint and transmission line design. The differential traces narrow down to a chip scale pitch of 150 μm allowing direct flip chip connections. This enabling the testing of millimeter wave integrated circuits without the need for probing. Furthermore, a 50GHz rat race coupler was fabricated to generate a differential clock from a single ended clock source

100 Gb/s serial transmission over copper using duo-binary signaling

At last year’s DesignCon we presented duo-binary signaling as an alternative for PAM4 for data rates of 56 Gb/s and higher over copper. This paper explores the feasibility of using duo-binary signaling for 100 Gb/s serial transmission over copper. It includes an in-depth comparison between duo-binary and other signaling schemes regarding the acceptable channel loss, the tolerable crosstalk and jitter and the power consumption for serial data rates up to 100 Gb/s, and we study what the channel requirements are to be able to use duo-binary signaling for 100 Gb/s serial transmission over copper

DAC-less and DSP-free PAM-4 transmitter at 112 Gb/s with two parallel GeSi electro-absorption modulators

Figure S5. The MAP of the reprogramming process in the WT model. The MAP (white curve) starting from the ME differentiated state (the blue point) to the pluripotent state (the green point) is different from that of differentiation process (Fig. 3A). The green dotted line is the ODE trajectory to compare with the MAP. (PDF 3338 kb