Optical modulators are at the heart of optical communication links. Ideally, they should feature low insertion loss, low drive voltage, large modulation bandwidth, high linearity, compact footprint and low manufacturing cost. Unfortunately, these criteria have only been achieved on separate occasions. Based on a Silicon and Lithium Niobate hybrid integration platform, we demonstrate Mach-Zehnder modulators that simultaneously fulfill these criteria. The presented device exhibits an insertion loss of 2.5 dB, voltage-length product of 2.2 V•cm, high linearity, electro-optic bandwidth of at least 70 GHz and modulation rates up to 112 Gbit/s. The high-performance modulator is realized by seamless integration of highcontrast waveguide based on Lithium Niobate -the most mature modulator material -with compact, low-loss silicon circuits. The hybrid platform demonstrated here allows for the combination of "best-in-breed" active and passive components, opening up new avenues for enabling future high-speed, energy efficient and cost-effective optical communication networks.

A continuous-time (CT) radio frequency (RF) antenna array beamformer and analog circuit based on a discrete-space-continuous-time (DSCT) 2-D fan-filter having transfer function is derived. The proposed transfer function is based on a 2-D FIR discrete domain fan filter. The discrete domain prototype is converted to the proposed mixed-domain DSCT analog filter by replacing unit sampled delays with CT analog first-order all-pass networks corresponding to the bilinear transform. First-order all-pass network is a poor approximation to a CT delay . To address this, a novel broadband pre-warping method is proposed to exactly compensate for such "bilinear warping". A 65 nm CMOS VLSI circuit for is proposed and an example fan filter with axis oriented at , half-fan-angle and maximum frequency is simulated employing closed-form expressions, an ABCD parameter based model and 65 nm CMOS simulations in Cadence. A stop-band interference rejection of 38 dB is verified by BSIM4 based simulations. The proposed circuit for operates at 3.7 mA from a 1.2 V supply. The beamfomer is shown to operate correctly in the presence of PVT variations of .Index Terms-Analog beamforming, CMOS, delay approximation, fan filter, VLSI.

In this paper, the specific characteristics of the Trichel pulse generated in wide point-to-plane discharge gaps are investigated and compared with those of the currents generated in narrow gaps. A set of empirical formulas are derived to describe the specific characteristics. The influence of the gap spacing both on the current characteristics and on the coefficients of the formulas is studied. Based on the experiment results, an improvement is made to the space charge calculation method proposed by Lama and Gallo [J. Appl. Phys. 45, 103–113 (1974)] and the calculation results are compared to the ones obtained with Lama and Gallo's original method. With the influence of the space charge considered, the modified method obtains more accurate results of the space charge accumulating in the gap and gives a more precise description of the motion of the space charge in the gap. Based on the calculation results, the influence of the space charge on the distribution of the electric field is examined and the influence of the gap spacing on the current characteristics is also studied.

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