Fabio Padovan

Design of Low-Noise

A study of K-band SiGe bipolar VCOs is reported in this paper. The design challenges related to the operation in the K-band and the use of a pure bipolar technology are discussed with particular emphasis to achieving low phase noise while using varactor diodes. Two different VCOs have been designed and fabricated. In the designs, the varactor is coupled to the active element by means of a magnetic transformer to avoid the use of tuning voltages exceeding the supply voltage. All the VCOs are operated in class-C. One of the designs features dynamic biasing to ensure robust start-up conditions. The VCOs feature a phase noise as low as -137 dBc/Hz at 10 MHz offset from the carrier. The VCOs show a state-of-the-art FOM of -189 dBc/Hz, and an excellent FOMT of -193 dB/Hz.

K

A K-band SiGe bipolar VCO operating from 18.9 to 22.1 GHz is presented. The oscillator features a phase noise as low as -136.5 dBc/Hz at 10 MHz offset from the 22.1 GHz carrier while drawing 10 mA from the 3.3 V supply. The VCO shows a state-of-the-art FOM of -188dBc/Hz and an excellent FOMT of -192dBc/Hz. The oscillator is tailored to the communication systems operating in the higher portion of the E-band. It is intended to be followed by a frequency multiplier by four, reported elsewhere.

-Band SiGe Bipolar VCOs: Theory and Implementation

This brief presents a 64-channel neural recording system-on-chip (SoC) with a 20-Mb/s wireless telemetry. Each channel of the analog front end consists of a low-noise bandpass amplifier, featuring a noise efficiency factor of 3.11 with an input-referred noise of 5.6 μVrms in a 0.001- to 10-kHz band and a 31.25-kSps 6-fJ/conversion-step 10-bit SAR analog-to-digital converter. The recorded signals are multiplexed in the digital domain and transmitted via an 11.7% efficiency pulse-position modulation ultrawideband transmitter, reaching a transmission range in excess of 7.5 m. The chip has been fabricated in a 130-nm CMOS process, measures 25 mm2, and dissipates 965 μW from a 0.5-V supply. This SoC features the lowest power per channel (15 μW) and the lowest energy per bit (48.2 pJ) among state-of-the-art wireless neural recording systems with a number of channels larger than 32. The proposed circuit is able to transmit the raw neural signal in a large bandwidth (up to 10 kHz) without performing any data compression or losing vital information, such as local field potentials.

A SiGe bipolar VCO for backhaul E-band communication systems

An UWB impulse radio transmitter for ultra-low energy neural recording applications is proposed. The transmitter is designed for robust and efficient operation in the 7.25-8.5GHz band, supporting communication ranges in excess to 4m. Powered by a low-voltage 0.5V supply, prototypes in a 130 nm CMOS technology are able to transmit 2.76 pJ/b PPM-modulated pulses to the antenna at a 20Mb/s data rate with an outstanding 11.7% overall energy efficiency.

A 64-Channel 965-

A 12 GHz VGA showing a gain variation range from -9 dB to 13 dB with a linear-in-dB gain control feature is presented in this work. As the gain is changed, the phase shift over the entire 10-14.4 GHz bandwidth varies as little as ≤ 2° due to a compensation circuitry that reduces the input-output phase shift sensitivity to gain variations in a robust manner with respect to temperature changes. Such a reduced phase shift variation is particularly useful to simplify the signal phase/amplitude control for the various paths of a phased array system, and allows to implement ultra-low sidelobe phased arrays. The VGA prototypes, implemented in a SiGe bipolar technology, show a noise figure of 5.1 dB, an IIP3 of -3 dBm, a P1dB of -17 dBm, and a power consumption of 83 mW.

\mu\text{W}

A BiCMOS VGA for the emerging 5G mobile communication systems operates from 15.5 to 39GHz with a maximum 17 dB gain, features 43 dB gain variation, and, due to the use of compensation circuits, it shows a reduced phase shift variation, namely 3° up to 30GHz for a gain variation of 23 dB. The VGA NF is 3.6-9 dB, its IIP3 is -1 dBm, while the power consumption is 104mW.

Neural Recording SoC With UWB Wireless Transmission in 130-nm CMOS

A 12GHz VGA is presented that shows a gain control from -9dB to 13dB in a linear-in-dB fashion. As the gain is changed, the phase shift over the entire 10 to 14.4 GHz bandwidth varies as little as ≤2° due to a compensation circuitry that reduces the input-output phase shift sensitivity to gain variations. The VGA prototypes, implemented in a SiGe bipolar technology, show a noise figure of 5.1 dB, an IIP3 of -3dBm, and a power consumption of 83mW.

A 20Mb/s, 2.76 pJ/b UWB impulse radio TX with 11.7% efficiency in 130 nm CMOS

A SiGe BiCMOS VCO with a transformer-coupled varactor operating from 12 to 15.9 GHz is presented. The oscillator core features a phase noise as low as -117dBc/Hz at 1 MHz offset from the 14.2 GHz carrier while drawing 8 mA from the 3.3 V supply. The VCO shows a state-of-the-art FOMt of -190dBc/Hz. The trade-off for the technology selection is described in the introduction. The oscillator is tailored to the communication systems for the upcoming 5G applications. New radios that will operate from 6 GHz to as high as 100 GHz may be needed.

A 12 GHz 22 dB-Gain-Control SiGe Bipolar VGA With 2° Phase-Shift Variation

The need for high-frequency, low-power, wide temperature range, precision on-chip reference clock generation makes relaxation oscillator topology an attractive solution for various automotive applications. This paper presents for the first time a 140MHz relaxation oscillator with robust-against-process-variation temperature compensation scheme. The high-frequency relaxation oscillator achieves 28 ppm/°C frequency stability over the automotive temperature range from −40 to 175°C. The circuit is fabricated in 40nm CMOS technology, occupies 0.009 mm2 and consumes 294µW from 1.2V supply.

A 15.5–39GHz BiCMOS VGA with phase shift compensation for 5G mobile communication transceivers

A SiGe BiCMOS Colpitts VCO with a transformer-coupled varactor operating from 18.8 to 23.1 GHz is presented. The Colpitts topology is leveraged to trade a slight degradation in the oscillator figure-of-merit for very low phase noise. The oscillator features a state-of-the-art phase noise of −119.4 dBc/Hz at 1 MHz offset from the carrier, while drawing 17.5 mA from the 4 V supply. The oscillator FoM is −188 dBc/Hz. The VCO also shows a wide 20.5% tuning range, which results in a FoMt = −194 dBc/Hz.