131,659 research outputs found
D-Band RX Front-End With a 0 –360 Phase Shifter Based on Programmable Passive Networks in SiGe-BiCMOS
No full textActive phased arrays are key enablers for high-capacity wireless links and imaging sensors at millimeter wave, but require advanced front-end circuits. On the receiver side, the front-end comprises a low-noise amplifier (LNA) followed by a programmable phase shifter (PS), required to adjust the phase of each channel before performing the coherent summation of the signals captured by different antenna elements. In D-band, conventional PSs based on the vector interpolation principle limit the dynamic range with a noise or linearity penalty due to transistors operating close to max, in currently available silicon technologies. This work presents a front-end where the variable phase shift is achieved using passive structures, with a noise figure equal to the insertion loss (IL) but inherently linear. Different passive networks providing a programmable phase shift in fine and coarse steps are developed and interleaved with active gain stages to build a 0 –360 PS. Cascode structures are used as gain stages, in the PS and in the preceding LNA, and reactive feedback is introduced around the common-emitter (CE) device to boost the gain. A D-band receiver front-end is implemented in BiCMOS 55-nm technology. With a power consumption of 80 mW from a 2 V supply, measurements prove 20 dB average gain, 130–170 GHz operating frequency with 0 –360 phase shift control, and average NF and of 7 dB and 2 dBm, respectively. Normalizing the dynamic range to power consumption, the achieved results compare favorably against state-of-the-art
Functional comparison of acoustic admittance measurements with a CMOS-compatible p-v microprobe and a reference one
No full textRecent developments in MEMS technology made available a new class of thermo-resistive sensors to be used as functional devices for acoustic particle velocity, v, measurements (Bruschi and Piotto, IEEE Sensors Proceedings 1405–1408, 2011). A very interesting feature of this new generation of v-sensors—distinguishing them from the Microflown® ones (de Bree et al., Sens Actuators A Phys 54:552–557, 1996)—is their compatibility with standard CMOS industrial processes, so allowing to integrate in the same chip both the sensors and read-out electronic circuits. This added flexibility of v-sensors, combined with miniature or MEMS microphones, allows of setting up pressure–velocity (p–v) microprobes for specific applications, in particular when the reduction of production costs is decisive for marketing strategies. In many applications, in fact, carefully designed functional devices can be safely used, without prejudice to the reliability and the robustness of the required measurement process. In other words, the required measurement precision can be achieved despite the low signal-to-noise ratio or limited band frequency response of the used p–v microprobes. This article shows a first comparison between the two kinds of sensor
A 20mW 130-175GHz Phase Shifter with Meandered λ/2 TLINEs in BiCMOS 55nm
No full textThis paper presents a compact and low-power D-Band four-quadrant active phase shifter using meandered λ/2 transmission-lines (TLINEs) for phase inversion. TLINE impairments (loss and phase deviation from 180°) are analyzed and their effects on the output vector space are discussed. A calibration technique is applied such that the phase shifter RMS amplitude and phase errors are kept under 1.2dB and 8°, respectively. Implemented in SiGe BiCMOS 55 nm, the proposed circuit covers 130- 175 GHz bandwidth with -4.5dB peak gain, O P 1 d B greater than -3dBm and 20mW average power consumption
A Compact Fault Tolerant 2-D Anemometer
No full textA compact anemometer capable of detecting both the magnitude and the direction of the wind in 2-D is presented. The device relies on a recently formalized principle, consisting in combining the differential pressures measured across distinct diameters of a cylinder exposed to the wind to estimate the wind velocity and the incidence angle. The cylinder includes an ad hoc microfluidic structure with three sections of diametric pressure probes connected in parallel. The multisection approach has been adopted in order to increase the reliability of the device. The prototype has been fabricated with stereolithographic printing, while commercial differential pressure sensors with low power consumption are used to read the pressures. The results of detailed experiments performed in a wind tunnel in the range 4–30 m/s are reported. A maximum angular error of 6◦ and a speed relative error less than 5.3% have been obtained
AM-AM and AM-PM Distortion in D-Band BiCMOS Vector-Interpolation Phase Shifters
No full textSub-THz phased-array transceivers need phase shifters for a coherent combination of the transmitted and received signals. Vector-interpolation phase shifters demonstrate wide bandwidth, low loss, and compact footprint, but may suffer from poor linearity, restrained by the need of high dynamic range variable gain amplifiers (VGAs). This article investigates the role of VGA impairments in a vector-interpolation phase shifter, with primary focus on the AM-AM and AM-PM distortions. Then, three common VGA structures are analyzed and compared, revealing a best candidate to optimize linearity. A single-ended input/output phase shifter is finally implemented in 55 nm SiGe BiCMOS technology. The test chip allows experimental validation of the theoretical results by using the VGAs in different operating modes. It is also shown that, in a single-ended phase shifter, the common-mode current generated by the VGAs may compromise gain and linearity. Solutions to the problem are introduced in the design, including a novel current-mode balun that provides large (4:1) impedance transformation and high common-mode rejection with equal primary and secondary inductors. Experimental results prove wideband operation, from 130 to 175 GHz, with 3.5 dB gain. The phase shift is programmable in 10° steps with rms phase and amplitude errors across frequency < 5° and < 0.8 dB, respectively. With the optimal VGA operation mode, the output power at 1 dB gain compression (OP1dB) is above 1.8 dBm with < 10° AM-PM distortion. Experiments compare favorably against previous works in the same band and in similar technologies
A Class AB CMOS Operational Amplifier for Application as Rail-to-Rail High Current Drive Buffer
No full textA class AB CMOS operational amplifier specially designed to be used as unity gain buffer is presented. The novelty of the presented topology consists in using a classical rail-to-rail OTA with duplicated output port to drive the gates of the op-amp complementary output transistors and relying on a separate feedback loop to limit the quiescent current. The simplicity of classical two stage op-amps is maintained with advantages in terms of die size, transient response and process independence. The circuit, fabricated using the BCD3S process of STMicroelectronics, occupies a die size of 0.06 mm2 and operates from a single 2.2V power supply with resistive loads as low as 300 Ω
A high current drive CMOS output stage with a tunabel quiescent current limiting circuit
No full textA CMOS output stage based on a complementary
common source with an original quiescent current limiting circuit
is presented. The quiescent current can be varied over a wide range
by means of a control current with no need to modify the transistor
aspect ratios. The output stage has been coupled to a conventional
complementary input stage to form a rail-to-rail buffer. A prototype
with the inclusion of auxiliary pins for biasing and current
monitoring purposes has been designed using the 1- m doublepolysilicon
BCD3S process of STMicroelectronics. On a single 5-V
power supply, the maximum output current is 20 mA. The amplifier,
biased for a total power dissipation of 1 mW, exhibits a total
harmonic distortion of 58 dB at 1 kHz with 4-V peak-to-peak on
a 330-
load. Correct operation of the quiescent current limiting
circuit has been demonstrated for a minimum supply voltage of
2.2 V
A flow sensor for liquids based on a single temperature sensor operated in pulsed mode
No full textAn anemometric flow sensor for liquids based on a single temperature sensor is presented. The sensor is based on a probe composed by
a silicon chip glued to a copper cylinder acting as thermal feed-through. A precise temperature sensor and a resistive heater are integrated
on the chip surface. The sensor is operated in pulsed mode to eliminate the interference of the fluid temperature, switching either the heater
power or the probe temperature. The results of water flow tests in the range (1–30) l/h are presented. The problem of reducing the duration
of the measurement cycle has been addressed with theoretical and experimental arguments
Single temperature sensor anemometer for liquid flow detection with pulsed heating driver
No full textIn this work we present an integrated
anemometer for liquids based on a single
temperature sensor. By means of a proportional
control loop, which utilises a PWM signal to
maintain the sensor temperature at a constant value,
the measurement time resulted four times faster
than the intrinsic thermal settling time of the sensor
Detailed Abundances of Red Giants in the Globular Cluster NGC 1851: C+N+O and the Origin of Multiple Populations
No full textWe present chemical abundance analysis of a sample of 15 red giant branch (RGB) stars of the globular cluster NGC 1851 distributed along the two RGBs of the (v, v-y) color-magnitude diagram. We determined abundances for C+N+O, Na, α, iron-peak, and s-elements. We found that the two RGB populations significantly differ in their light (N, O, Na) and s-element content. On the other hand, they do not show any significant difference in their α and iron-peak element content. More importantly, the two RGB populations do not show any significant difference in their total C+N+O content. Our results do not support previous hypotheses suggesting that the origins of the two RGBs and the two subgiant branches of the cluster are related to different content of either α (including Ca) or iron-peak elements, or C+N+O abundance, due to a second generation polluted by Type II supernovae
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