Lorenzo Tripodi

RF Characterization of Schottky Diodes in 65-nm CMOS

Schottky diodes in 65-nm CMOS have been designed, measured up to 67 GHz, and modeled in the reverse-bias voltage range. An array of 8 × 8 minimum-sized parallel diode junctions is compared with a single-junction diode and to linear arrays of 3, 12, and 64 elements of the same total area. An iterative analysis method and a more detailed equivalent circuit than that used in previous work are developed to extract the junction capacitance, the stray capacitance, and the series resistances separately. Based on the equivalent circuit model, the extrapolation of the diode RF behavior to frequencies beyond the measurement range is discussed. The relevance of the cutoff frequency of the Schottky junction itself for evaluation of the suitability of the diodes in millimeter-wave and terahertz applications is explained.

Broadband CMOS Millimeter-Wave Frequency Multiplier With Vivaldi Antenna in 3-D Chip-Scale Packaging

This paper describes a frequency multiplier able to emit a broadband signal with a frequency range from 70 GHz up to at least 170 GHz. The device is composed of a nonlinear transmission line (NLTL) implemented in commercial CMOS 65-nm technology and an off-chip Vivaldi antenna. These two elements are packaged together with a 3-D chip-scale packaging technology. Characterization of the whole device and of the standalone NLTL is presented at frequencies up to 170 GHz.

65-nm CMOS Monolithically Integrated Subterahertz Transmitter

This letter presents a transmitter for subterahertz radiation (up to 160 GHz), which consists of a nonlinear transmission line (NLTL) and an extremely wideband (EWB) slot antenna on a silicon substrate of low resistivity (10 Ω·cm). The fabrication was realized using a commercially available 65-nm CMOS process. On-wafer characterization of the whole transmitter, of the stand-alone EWB antenna, and of the stand-alone NLTL is presented. Reflection measurements show that the stand-alone EWB antenna has a -10-dB impedance bandwidth in the frequency bands of 75-100 GHz and 220-325 GHz, which agrees very well with the simulation results. The simulated radiation patterns of the antenna are also presented, indicating that the transmitter has an ominidirectional performance. The output power of the NLTL alone and of the transmitter is measured up to 160 GHz, from which the power gain of the on-chip antenna is derived and has a maximum value of -9.5 dBi between 90 and 120 GHz.

Low-noise variable-gain amplifier in 90-nm CMOS for TV on mobile

Presented is a low-noise variable-gain amplifier intended for handheld TV-on-mobile in the UHF band. The circuitry, implemented in 90-nm CMOS technology, is designed for compliance with MBRAI category 2 and 3 and for robustness against the high RF input levels caused by uplink signals from cellular and connectivity services integrated in the same handheld. The overall Noise Figure is kept low by employing lossless feedback in the VGA. The effect of a back- gate control to reduce the sensitivity of the amplifier characteristics to variations in supply voltage has been studied. The test chip realized exhibits 23 dB gain that can be stepped down with 2 dB resolution, 2.6 dB NF, a -5.4 dBm IIP3 at maximum gain and 40 mW power consumption at 1.2 V supply.

Extremely wideband CMOS circuits for future THz applications

Recent results in IC design have demonstrated the possibility to realize CMOS circuits working in the 100 GHz-1 THz band. In this chapter the design and measurements of a CMOS nonlinear transmission line and a CMOS Schottky diode sampling bridge are presented. Large-signal measurements of the nonlinear transmission lines from 6 to 168 GHz are shown. Time-domain measurements showing the possibility to sample ultrafast signals with fall time of 4.6 ps are described too. These two extremely wide band devices will be used as essential building blocks for the future implementation of a CMOS-based coherent THz spectrometer and imager.

A broadband RF 65nm CMOS front-end for cable TV reception

A novel broadband RF front-end in 65nm CMOS technology is presented. The front-end serves to precondition the incoming RF spectrum for further processing in a cable TV receiver architecture where RF channel selection and down conversion are done in digital domain. The analog front-end consists of a broadband highly linear low-noise amplifier followed by a variable gain RF amplifier. An original broadband circuit topology for the amplifiers is adopted. The fabricated front-end exhibits a bandwidth of 50-1050MHz, a variable gain, which spans from 12 to 37dB with a 0.2dB step, an OIP3 of 28.4dBm (77.5dBmV), an OIP2 of 65dBm (114dBmV), and a noise figure of 5.8dB, dissipating 125mW at 1.2V supply, and a core silicon area of 0.4mm^2.

Broadband sub-THz spectroscopy modules integrated in 65-nm CMOS technology

The design and characterization of a broadband 20–480 GHz continuously tuneable on-chip spectrometer based on non-linear transmission lines in 65-nm CMOS technology is presented. The design procedure of the sampler that detects the ultra-broadband signal from the transmitter in time and frequency domain is described in detail. It consists of a non-linear transmission line, a passive pulse differentiator and a high-speed sample and hold-circuit. The relevance of the layout of the Schottky diodes in the sampler with a maximum RC-cutoff frequency of 430 GHz is described. Time domain and frequency domain measurements are presented to characterize the 480 GHz sampler bandwidth as well as the 3.1 ps sampler rise time. A signal to noise ratio of 90 dB at 100 GHz, 70 dB at 200 GHz and more than 30 dB at 480 GHz is reached. Two implementation of the spectrometer with antennas are presented, one with an on-chip antenna and one in a hybrid package. The antenna-less on-chip implementation of the transmitter and sampler requires no external lenses and is miniaturized to an area of 3 mm 2 . Future applications include analysis of fluids in microfluidic packages or droplet analysis in bio-medical or pharmaceutical applications.