Tuning Of Oscillation Frequency Research Articles

The development of W waveband diffraction radiation oscillator

This study presents the development of a continuous wave diffraction radiation oscillator utilizing a sheet electron beam. The oscillator comprises a slow-wave system formed by double-comb gratings, an open resonant cavity consisting of a spherically curved mirror and a cylindrically curved mirror, and a sheet electron beam generated by a diode gun. A permanent magnetic focusing system stabilizes the transmission of the sheet electron beam within the slow-wave system. Through a combination of mechanical and electronic tuning, the oscillator generates stable signal output in the TEM00q mode. The oscillator's frequency tuning range spans from 87 to 97 GHz, achieving a maximum output power of 13.5 W.

Nonlinear dynamics of a spin-Hall nano-oscillator based on the canted antiferromagnet.

The theory of the nonlinear dynamics of a canted antiferromagnet-based (AFM) spin-Hall oscillator with weak ferromagnetism caused by the strong Dzyaloshinskii-Moriya interaction between magnetic sublattices is rigorously studied. The AFM oscillator's frequency tuning is carried out both due to a DC spin-polarized current flowing through the normal metal layer and an external permanent magnetic field. A feature of the operation of this oscillator is the presence of a hysteresis region between the subcritical (damping) and overcritical (self-oscillating) regimes. We show that it is necessary to reduce an effective easy-plane anisotropy field of the AFM or choose antiferromagnetic material with a smaller exchange field between magnetic sublattices to get a smaller hysteresis region. The action of an external permanent magnetic field on an antiferromagnet leads to the presence of two stable equilibrium states, and the self-oscillating regime is characterized by two-mode generation. We find the conditions for the absence of two-mode generation on the "current density-magnetic field strength" plane. We believe that our results can be helpful for the practical development of a sub-THz frequency tunable oscillator based on the AFM with weak ferromagnetism.

An 18–19.2 GHz Voltage-Controlled Oscillator with a Compact Varactor-Only Capacitor Array

This paper presents a K-band CMOS cross-coupled pair voltage-controlled oscillator (VCO) that utilizes the varactor-only capacitor network. The proposed circuit features low parasitics and a compact capacitor network, such that the varactor in the analog tuning path directly affects the oscillation frequency with a large gain of the VCO, and the varactor in the digital tuning path results in minimal noise sources, thus achieving low phase noise for the automotive FMCW radar application. This VCO was designed using TSMC 65 nm technology, and the post-layout simulation results show a stable oscillation across 18–19.2 GHz, a minimum phase noise of −105.9 and −128 dBc/Hz at 1- and 10-MHz offset frequencies while dissipating 21 mW of power from a 1 V supply. Furthermore, no notable variations in phase noise are observed across the oscillation frequency tuning range. It reveals a figure of merit (FOM) of −178.3 dBc/Hz while using a varactor-only capacitor array and occupying a small chip area.

Bendable 190-GHz Transmitter on 20-μm Ultra-Thin SiGe BiCMOS

This research work presents the fabrication and characterization of ultra-thin fully integrated transmitter circuits. By moving bendable technology into the 190-GHz band, it is possible to implement complete transmitter systems or sensor nodes, including on-chip antennas, on a single chip without the need for surrounding circuits, thus increasing system performance and reducing cost. To fabricate such thin chips, a standard 700-<inline-formula> <tex-math notation="LaTeX">$\mathrm {\mu }\text{m}$ </tex-math></inline-formula> fully processed SiGe BiCMOS wafer was thinned to a thickness of only 20 <inline-formula> <tex-math notation="LaTeX">$\mathrm {\mu }\text{m}$ </tex-math></inline-formula> making the silicon bendable. The transmitter, which consists of a voltage-controlled oscillator, a power amplifier, and an on-chip antenna, was characterized by comparing thinned and standard thickness samples. Therefore, a maximum relative deviation of the oscillator frequency tuning of less than 2&#x0025; was found. The oscillation frequency of the chip is measured in a bent state, resulting in a maximum relative deviation for bend radii of up to 4 mm of only 1&#x0025;. Considering a maximum output power deviation of 4.6 dB, the presented approach proves to be feasible for the design of flexible high-performance integrated systems. This enables novel applications in the field of medicine, wearable electronics, and the Internet of Things.

X-band CMOS VCO for 5 GHz Wireless LAN

The implementation of a low phase noise voltage controlled oscillator (VCO) is important for the signal integrity of wireless communication terminal. A low phase noise wideband VCO for a wireless local area network (WLAN) application is presented in this paper. A 6-bit coarse tune capacitor bank (capbank) and a fine tune varactor are used in the VCO to cover the target band. The simulated oscillation frequency tuning range is from 8.6 to 11.6 GHz. The proposed VCO is desgned using 65 nm CMOS technology with a high quality (Q) factor bondwire inductor. The VCO is biased with 1.8 V VDD and shows 9.7 mA current consumption. The VCO exhibits a phase noise of –122.77 and -111.14 dBc/Hz at 1 MHz offset from 8.6 and 11.6 GHz carrier frequency, respectively. The calculated figure of merit(FOM) is -189 dBC/Hz at 1 MHz offset from 8.6 GHz carrier. The simulated results show that the proposed VCO performance satisfies the required specification of WLAN standard.

300-GHz InP HBT Quadrature VCO With Integrated Mixer

A 300-GHz quadrature voltage-controlled oscillator (QVCO) integrated with a pair of mixers based on an InP heterojunction bipolar transistor (HBT) technology has been developed. A super-harmonic coupling technique was applied to generate the quadrature signal in the QVCO. The oscillation frequency tuning range is 24.8 GHz (from 286.1 to 310.9 GHz), and the frequency range maintaining the quadrature operation (within ±10°) is 4.8 GHz (297.2–302.0 GHz). The maximum output power of the QVCO was measured as 0.46 dBm at 286.3 GHz. The measured phase noise is −91.4 dBc/Hz with 10 MHz offset at 294.2 GHz. The integrated QVCO-mixer consumes a dc power of 167.5 mW.

Wideband 67−116 GHz receiver development for ALMA Band 2

Context. The Atacama Large Millimeter/submillimeter Array (ALMA) has been in operation since 2011, but it has not yet been populated with the full suite of its planned frequency bands. In particular, ALMA Band 2 (67−90 GHz) is the final band in the original ALMA band definition to be approved for production. Aims. We aim to produce a wideband, tuneable, sideband-separating receiver with 28 GHz of instantaneous bandwidth per polarisation operating in the sky frequency range of 67−116 GHz. Our design anticipates new ALMA requirements following the recommendations of the 2030 ALMA Development Roadmap. Methods. The cryogenic cartridge is designed to be compatible with the ALMA Band 2 cartridge slot, where the coldest components – the feedhorns, orthomode transducers, and cryogenic low noise amplifiers – operate at a temperature of 15 K. We use multiple simulation methods and tools to optimise our designs for both the passive optics and the active components. The cryogenic cartridge is interfaced with a room-temperature (warm) cartridge hosting the local oscillator and the downconverter module. This warm cartridge is largely based on GaAs semiconductor technology and is optimised to match the cryogenic receiver bandwidth with the required instantaneous local oscillator frequency tuning range. Results. Our collaboration has resulted in the design, fabrication, and testing of multiple technical solutions for each of the receiver components, producing a state-of-the-art receiver covering the full ALMA Band 2 and 3 atmospheric window. The receiver is suitable for deployment on ALMA in the coming years and it is capable of dual-polarisation, sideband-separating observations in intermediate frequency bands spanning 4−18 GHz for a total of 28 GHz on-sky bandwidth per polarisation channel. Conclusions. We conclude that the 67−116 GHz wideband implementation for ALMA Band 2 is now feasible and that this receiver provides a compelling instrumental upgrade for ALMA that will enhance observational capabilities and scientific reach.

A novel linear square/triangular wave generator with tunable duty cycle

A novel circuit of square/triangular wave generator consists of single multiple output dual-X current conveyor transconductance amplifier (MO-DXCCTA), one grounded resistor and one grounded capacitor is proposed. One square wave in current mode and one triangular wave in voltage mode are simultaneously available from the proposed generator. The proposed circuit is fully electronically controllable facilitating the feature of duty cycle adjustment. The duty cycle is electronically tunable via bias current. Moreover, a wide sweep of oscillation frequency is possible via grounded capacitor with very good linearity. The tuning of oscillation frequency does not affect the amplitudes of output waveforms. Furthermore, the oscillation frequency can also be controlled electronically and independently via bias current for a fixed duty cycle of 50%. A prototype of MO-DXCCTA using commercial ICs (AD844 and LM13700) is used to carry out the experimental results. Measured results show very good variation of frequency (up to 245.5 kHz) against capacitor with nonlinearity less than 2%.

A 310–340-GHz Coupled-Line Voltage-Controlled Oscillator Based on 0.25-$\mu$m InP HBT Technology

A THz voltage-controlled oscillator (VCO) has been developed in this work based on a 0.25- μm InP heterojunction bipolar transistor (HBT) technology. The cross-coupled push-push oscillator adopted a novel coupled-line topology, in which the DC blocking capacitors and the load inductance are replaced by a pair of coupled-lines to improve the oscillation frequency and reduce the circuit area. Also, a base bias tuning was employed for effective oscillation frequency tuning. The circuit exhibited the voltage tuning from 309.5 GHz to 339.5 GHz, leading to a tuning range of 30 GHz. The maximum output power was -6.5 dBm at 334 GHz, achieved with a dc power consumption of 13.5 mW. Measured phase noise was -86.55 at 10-MHz offset. The circuit occupies only 0.014 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> excluding the probing pads.

Frequency-tunable relativistic coaxial backward-wave oscillator with a modulating reflector

The theoretical and numerical analyses of a relativistic backward-wave tube with a coaxial slow-wave structure and modulating reflector are carried out. The incident working TEM mode reflects because of a coaxial TM01 mode excited in the reflector at a near-cutoff frequency. It is shown that the longitudinal component of the electric field present near the reflector provides the energy premodulation of an electron beam and conditions for oscillation frequency tuning. The mechanical tuning of the oscillation frequency of a relativistic coaxial backward-wave oscillator with a modulating reflector within 10% is demonstrated in numerical simulation and experiment. Tuning is accomplished by varying the drift length between the reflector and the entrance to the slow-wave structure of the oscillator.

OTRA Based Voltage Mode Third Order Quadrature Oscillator

Two topologies of operational transresistance (OTRA) based third order quadrature oscillators (QO) are proposed in this paper. The proposed oscillators are designed using a combination of lossy and lossless integrators. The proposed topologies can be made fully integrated by implementing the resistors using matched transistors operating in linear region, which also facilitates electronic tuning of oscillation frequency. The nonideality analysis of the circuit is also given and for high frequency applications self-compensation can be used. Workability of the proposed QOs is verified through PSPICE simulations using 0.5 μm AGILENT CMOS process parameters. The total harmonic distortion (THD) for both the QO designs is found to be less than 1%.

Resistor-less current-mode four-phase quadrature oscillator using CCCDTAs and grounded capacitors

Abstract A current-mode four-phase quadrature oscillator (FPQO) using 2 current controlled current differencing transconductance amplifiers (CCCDTAs) and 2 grounded capacitors is presented. The proposed oscillator can provide 4 sinusoidal output currents with 90 phase difference. The oscillation condition and oscillation frequency can be controlled independently and electronically by adjusting the bias currents of the CCCDTA. Both the oscillation condition and oscillation frequency tuning laws are non-interactive and dual-current controlled. High output impedances of the configuration enable the circuit to be cascaded without additional current buffers. The use of only grounded capacitors is ideal for integration. The circuit performances are depicted through PSPICE simulations, they show good agreement to theoretical anticipation.

Linearization of oscillation frequency for integrated LC-VCO with inversion-mode varactor

Metal-oxide semiconductor (MOS) varactors are widely used in voltage-controlled oscillators (VCOs) due to the need for a tunable capacitance. Two types of varactors that have been integrated on-chip include the inversion-mode and accumulation-mode types. The inversion-mode varactor offers immunity to latch-up, but suffers from a non-linear C(V) characteristic which directly leads to a nonlinear oscillation frequency tuning curve. This paper proposes an oscillation frequency linearization technique for LC-VCO with an inversion-mode varactor. The linearity of the frequency tuning curve is improved by linearization of C(V) characteristics of the inversion-mode varactor. A new varactor configuration consisting of varactor units and resistor divider network is proposed. The single-switch integrated LC-VCO with the proposed varactor configuration is fabricated in TSMC 0.18 μm CMOS technology. The improvement of linearity of the frequency tuning curve has been verified using mathematical models and measurement results.

Design of a high tuning range and low phase noise transformer-based LC voltage-controlled oscillator

This article proposes a wide tuning voltage-controlled oscillator (VCO) by employing a transformer-based LC-tank and is fabricated in a TSMC 0.18 μm CMOS process with 1.5 V supply voltage. We choose decoupling effect to decrease primary and secondary inductances and then decrease quality factors to obtain higher oscillation frequency and wide tuning range. Measurement results show that at the supply voltage of 1.5 V, the proposed VCO is tunable from 5.96 GHz to 7.3 GHz corresponding to a tuning range of 20.1%, the measured phase noise is −110.9 dBc/Hz at 1 MHz offset from the oscillation frequency of 5.97 GHz, the total power consumption is 9.51 mW with an output signal power of −4.74 dBm at the frequency of 6.2 GHz. The chip area including pads occupies only 0.69 × 0.696 mm2. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1165–1169, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25908

An Organic FET SRAM With Back Gate to Increase Static Noise Margin and Its Application to Braille Sheet Display

An integrated system of organic FETs (OFETs) and plastic actuators is proposed, and it is applied to a Braille sheet display. Some circuit technologies are presented to enhance the speed and the lifetime for the Braille sheet display. An OFET SRAM is developed to hide the slow transition of the actuators. Developed five-transistor SRAM cell reduces the number of the bit lines by one-half and reduces the SRAM cell area by 20%. Pipelining the write-operation reduced the SRAM write-time by 69%. Threshold voltage control technology using a back gate increased the static noise margin of SRAM and compensated for the chemical degradation of the OFETs after 15 days. The oscillation frequency tuning range from -82% to +13% in a five-stage ring oscillator is also demonstrated with the threshold voltage control technology. The overdrive techniques for the driver OFETs reduced the transition time of the actuator from 34 s to 2 s. These developed circuit technologies achieved the practical 1.75-s operation to change all 144 Braille dots on Braille sheet display and will be essential for the future large area electronics made with OFETs

Frequency-Tunable CW Gyro-BWO With a Helically Rippled Operating Waveguide

Operation of a continuous wave gyrotron backward-wave oscillator (gyro-BWO) with a helically rippled operating waveguide has been experimentally studied. The gyro-BWO exploits a dc oil-cooled magnet with magnetic field up to 0.5 T and utilizes a weakly relativistic (20 keV) electron beam produced by a magnetron injection gun. Stable generation at the second cyclotron harmonic with a maximum power of 7 kW and an efficiency of 15% at a frequency of 24.7 GHz was achieved. Smooth oscillation frequency tuning by varying the magnetic field was measured to be as wide as 5% at the half-power level. The first gyro-BWO operation with a single-stage energy recovery system was realized. The use of a depressed collector provided an efficiency increase up to 23% and an opportunity for reduction of the main power supply voltage down to 10 kV.

All-optical control of clock frequency division using injection-locked Fabry–Perot laser diode

All-optical clock-division from 10 to 5 GHz has been demonstrated based on period doubling in an injection-locked Fabry–Perot laser diode. The division process can be controlled by additional light injection through optical tuning of the laser relaxation oscillation frequency. A response time within tens of picoseconds has been obtained. By adjusting the DC bias, the clock-divider can also operate under different input frequencies from 8 to 11 GHz.

Fully monolithically integrated feedback voltage controlled oscillator [using PHEMTs

A fully monolithically integrated voltage controlled oscillator (VCO) using feedback technique is presented here. The circuit provides oscillation within the frequency range of 6.3-7.0 GHz. The corresponding tunable relative bandwidth is 10%. The feedback topology proves to provide a good linearity of the oscillation frequency dependence versus tuning voltage. The maximal deviation of the frequency behavior from its linear fit is /spl Delta/f=39 MHz. It is shown in the following that the feedback technique can be used for broadband VCO design.

Optical parametric oscillator frequency tuning and control

The frequency-tuning and -control properties of monolithic doubly resonant optical parametric oscillators are analyzed for stable single-mode pump radiation. Single-axial-mode operation is observed on the idler and the signal for both pulsed and continuous pumping. Projections are made for tuning-parameter tolerances that are required for maintenance of stable single-frequency oscillation. Continuous frequency tuning is possible through the simultaneous adjustment of two or three parameters; thus the synthesis of specific frequencies within the broad tuning range of the doubly resonant optical parametric oscillator is permitted.

Wide Frequency‐Modulation Operation of Semiconductor Lasers Using a Composite‐Optical Cavity

AbstractIn the optical heterodyne communication and measurement based on semiconductor lasers, selection of an arbitrary frequency within a broad gain spectral width and continuous and broadband FM operation are needed. This paper reports a theoretical study on a laser diode (LD) with a composite optical cavity using an external reflector. Using a GaAlAs LD with an adjacent plane or spherical mirror, a broadband tuning of oscillation frequency of about 8 THz (18 nm) becomes possible by variation of the external cavity length. Further, by modulation of the injection current, a continuous FM shift as large as 150 to 290 GHz is realizable which is three to five times the conventional value.