Local Oscillator Signal Generation Research Articles

Fiber-terahertz-fiber bridge system in the 355-GHz band using a simple optical frequency comb and a photonics-enabled receiver.

This Letter demonstrates a high-speed fiber-terahertz-fiber system in the 355-GHz band using stable optical frequency comb generation and a photonics-enabled receiver. At the transmitter, a single dual-drive Mach-Zehnder modulator is employed to generate a frequency comb by driving the modulator under an optimal condition. At the antenna site, a photonics-enabled receiver consisting of an optical local oscillator signal generator, a frequency doubler, and an electronic mixer is used to downconvert the terahertz-wave signal to the microwave band. Simple intensity modulation and a direct detection method are used for transmitting the downconverted signal to the receiver over the second fiber link. To demonstrate the proof of concept, we transmitted a 16-quadrature amplitude modulation (QAM) orthogonal frequency-division multiplexing signal over a system consisting of two radio-over-fiber links and a 4 m wireless link in the 355-GHz band and achieved a line rate of 60 Gb/s. We also successfully transmitted a 16-QAM subcarrier multiplexing single-carrier signal over the system and achieved a capacity of 50 Gb/s. The proposed system can facilitate the deployment of ultra-dense small cells in high-frequency bands in beyond-5G networks.

A low power 0.5–3.0 GHz passive mixer based wideband receiver front-end

A 0.5–3.0 GHz passive mixer based receiver front-end (RFE) is presented. This RFE consists of low noise amplifier, passive mixer, transimpedance amplifier (TIA) and local oscillator signal generator. In order to reduce the power consumption and noise figure, an optimized LNA is proposed in this paper. To further reduce the power consumption, topology of TIA is simplified. The chip is fabricated with SMIC 65 nm technology. At the frequency band of 0.5–3.0 GHz, it achieves a gain of 34 dB and NF of 3.2 dB. The power consumption is 3.8–5.0 mW with core area of 0.06 mm2.

Photonics-Assisted Frequency Up/Down Conversion With Tunable OEO and Phase Shift

A novel photonics-assisted method for frequency up/down-conversion based on an integrated dual-polarization dual-parallel Mach–Zehnder modulator (DP-DPMZM) with tunable optoelectronic oscillator (OEO) and phase shift is presented. The local oscillator (LO) signal with high spectral purity and low phase noise is generated by an OEO loop in one of the sub-DPMZMs. The frequency can be adjusted by an electrical bandpass filter (EBPF). The radio frequency (RF) signal is injected into another sub-DPMZM. The carrier-suppressed single-sideband (CS-SSB) modulation of both the LO and RF signals is achieved. The phase of the converted signal can be tuned by an integrated dual-channel phase modulator (DPM). Frequency up/down-conversion can be switched by tuning a single bias voltage of the DP-DPMZM. Multiple functions, including tunable LO signal generation, up/down-conversion and phase shifting, can be realized. Moreover, dispersion-induced power fading is well compensated due to CS-SSB modulation. In the experiments, the tunable LO signal from 5 to 18 GHz, with a sidemode suppression ratio as high as 46.1 dB and a phase noise level of −104.5 dBc/Hz @ 10 kHz at 10 GHz, is generated successfully. The spur suppression ratios of the up/down-converted signals are 32.6 dB and 35.6 dB, respectively. The up/down conversion performance for RF carrying 16 quadrature amplitude modulation (16-QAM) signal is also investigated. The phase shifting of dual-channel converted signals can be varied continuously and independently in the range of 0–360°, and the phase deviation is ±1.8°. The proposed compact link is characterized by function multiplexing and inherent dispersion compensation.

Phase Locking in Millimeter Wave Frequency Synthesizers - Design overview of Charge Pump Phase Locked Loops

Phase Locked Loops are key blocks which are widely adopted in all area of electronics, especially transceivers in wireless communication systems. The application of Phase Locked Loop varies from generation of local oscillator signal for upconversion and down conversion, generation and distribution of clock signals and jitter reduction. The most extensive use of Phase Locked Loop is for frequency synthesis. The requirements of synthesizer architectures depend on various system requirements and specifications which are based on regulatory standards. The design of Phase Locked Loop components involves the consideration of various techniques to resolve the nonidealities at front end high frequency components as well as back end low frequency components. This paper presents the background and importance of a Phase Locked Loop, various approaches over the years, design choices for each block and practical design methodology for Charge Pump Phase Locked Loops. This paper also presents the system level design of Phase Locked Loop and supply noise interactions among sub modules inside a charge pump Phase Locked Loop

A Scalable Four-Channel Frequency-Division Multiplexing MIMO Radar Utilizing Single-Sideband Delta–Sigma Modulation

A scalable four-channel multiple-input multiple-output (MIMO) radar that features a modular system architecture and a novel frequency-division multiplexing approach is presented in this article. It includes a single 30-GHz voltage-controlled oscillator (VCO) for the local oscillator signal generation, four cascaded 120-GHz transceivers with a frequency quadrupler, and on-board differential series-fed patch antennas. The utilized uniform antenna configuration results in 16 virtual array elements and enables an angular resolution of 6.2°. The vector modulators in the transmit (TX) paths allow the application of complex bit streams of second-order delta-sigma modulators easily generated on a field-programmable gate array (FPGA) to implement single-sideband (SSB) modulation on the TX signals resulting in orthogonal waveforms for the MIMO operation. Only one phase-locked loop and no digital-to-analog converter is required. The waveform diversity also allows the simultaneous transmission of the TX signals to reduce the measurement time. The application of the SSB modulation on the frequency-modulated continuous-wave MIMO radar requires only half of the intermediate frequency bandwidth compared with the double-sideband modulation. The issue of the phase and amplitude mismatches at the virtual array elements due to the scalable radar architecture is addressed and a calibration solution is introduced in this article. Radar measurements using different numbers of virtual array elements were compared and the digital-beamforming method was applied to the results to create 2-D images.

Microwave Downconversion by a Tunable Optoelectronic Oscillator Based on PS-FBG and Polarization-Multiplexed Dual loop

A novel photonic method for microwave downconversion by using a tunable optoelectronic oscillator (OEO) based on a phase-shifted fiber-Bragg grating (PS-FBG) and the polarization-multiplexed dual loop is proposed and investigated. By the virtue of the narrow notch bandwidth of the PS-FBG and the side-mode suppression of the optimized dual loop, the frequency tunable local oscillator (LO) signal with high spectral purity and low phase noise is generated by changing the frequency of the optical carrier from the laser source. The microwave downconversion is conducted directly by inputting the radio frequency (RF) signal into the OEO without any additional components. The experiment of the LO signal generation and the microwave downconversion is carried out. The frequency tunable LO signals from 2.5 to 7 GHz with the side-mode suppression ratio as high as 56 dB and the phase noise of −109 dBc/Hz at 10 kHz are generated successfully. By tuning the LO frequency generated by the proposed OEO, the RF signals with different frequencies from 3.5 to 8 GHz are converted to the same intermediate frequency band of 1 GHz. The spurious-free dynamic range of the downconversion system is measured to be 102.2 dB $\cdot $ Hz $^{2/3}$ . The downconversion performance for RF carrying 16 quadrature amplitude modulation signal is also analyzed.

Analysis and design of LC oscillators associated with frequency multipliers: a phase noise perspective

SummaryWhen a local oscillator signal generation system is based on an LC oscillator and a frequency multiplier, the question of determining the optimal multiplication factor is a key issue. In this paper, the problem is addressed in order to minimize the 1/f2 phase noise within a tuning range constraint. The analysis, with a practical graphical representation, reveals the oscillator phase noise dependence on the oscillating frequency in the transition from two different regimes, named the inductor‐limited quality factor and the capacitor‐limited quality factor. The results obtained enable the evaluation of the phase noise performance of systems based on a sub‐harmonic and super‐harmonic oscillators and how they compare with an oscillator in the fundamental mode. Crucial questions like the phase noise improvement that these systems can achieve are analytically answered. A design methodology is thus proposed and verified through measurements on a frequency source at 31 GHz, composed by a sub‐harmonic voltage‐controlled oscillator followed by an injection‐locked frequency tripler, dedicated to backhauling applications, designed on a BiCMOS process technology. The tuning range is 10%, and the phase noise at a 1‐MHz offset is −112 dBc/Hz. Copyright © 2017 John Wiley & Sons, Ltd.

A 30-MHz–3-GHz CMOS Array Receiver With Frequency and Spatial Interference Filtering for Adaptive Multi-Antenna Systems

A 30-MHz–3-GHz wideband complementary metal–oxide–semiconductor phased array receiver with interference suppression capability in the frequency and spatial domains is presented. A frequency filtering function is provided by a two-stage harmonic rejection mixer with 16-phase local oscillator (LO) signals that are generated by frequency dividers and phase interpolators. The developed IC suppresses third- to seventh-order harmonic interference by more than 55 dB in a wide range from 30 MHz to 3 GHz. The 16-phase LO signal generator combined with a 2-b baseband phase shifter (PS) also works as a 6-b PS. Equipped with a 6-b amplitude control in addition to the 6-b phase control, the array receiver enables analog null steering that can reduce a spatial interference coming from a specific direction. The multi-chip synchronization needed for the null steering function is realized with pre-set circuits in the frequency dividers. Space propagation measurements made on a four-element array antenna system using the developed ICs indicated that the null steering function reduces spatial interference by 20 dB and reduces the error vector magnitude of a 2-GHz radio frequency, 20-MHz bandwidth, and 64-quadrature amplitude modulation signal from −12.7 to −26.3 dB even when a strong interferer exists.

An I/Q mixer with an integrated differential quadrature all-pass filter for on-chip quadrature LO signal generation**Project supported by the National High Technology Research and Development Program of China (No. 2011AA010200).

A down-conversion in-phase/quadrature (I/Q) mixer employing a folded-type topology, integrated with a passive differential quadrature all-pass filter (D-QAF), in order to realize the final down-conversion stage of a 60 GHz receiver architecture is presented in this work. Instead of employing conventional quadrature generation techniques such as a polyphase filter or a frequency divider for the local oscillator (LO) of the mixer, a passive D-QAF structure is employed. Fabricated in a 65 nm CMOS process, the mixer exhibits a voltage gain of 7–8 dB in an intermediate frequency (IF) band ranging from 10 MHz–1.75 GHz. A fixed LO frequency of 12 GHz is used to down-convert a radio frequency (RF) band of 10.25–13.75 GHz. The mixer displays a third order input referred intercept point (IIP3) ranging from −8.75 to −7.37 dBm for a fixed IF frequency of 10 MHz and a minimum single-sideband noise figure (SSB-NF) of 11.3 dB. The mixer draws a current of 6 mA from a 1.2 V supply voltage dissipating a power of 7.2 mW.

Passive mixer with 24-GHz LO signal generator for low-power receiver

A passive mixer with 24-GHz local oscillator (LO) signal generator is proposed for low-power receiver. The proposed circuit is designed and fabricated in 130-nm CMOS technology. With the 24-GHz LO signal, the mixer can down-convert the radio frequency (RF) signal to the intermediate frequency (IF) signal. At a supply voltage of 1.3 V, the proposed circuit has the power consumption of 11.86 mW, which is applicable for low power system.

Live Electrooptic Imaging of $W$-Band Waves

A novel method for real-time visual observation of traveling -band waves is described. Wave images and movies are acquired by a live electrooptic imaging (LEI) camera equipped with an optical source that emits signals modulated at a local oscillator (LO) frequency in the -band range. Waves propagating in a slab waveguide made of a semiconductor plate as well as in the air are successfully visualized. Especially in this paper, -band wave images for the aerial propagation in a variety of forms are presented: spherical and plane waves together with some fundamental wave phenomena such as reflection, interference, and diffraction at metal-air interfaces. The principle of 100-GHz optical LO signal generation at the optical wavelength of 780 nm as well as performance parameters such as the spatial resolution, bandwidth, and dynamic range of the camera are discussed. Further, some preliminary applications of the scheme are presented.

A 24-GHz Receiver Frontend With an LO Signal Generator in 0.18-$\mu$m CMOS

Utilizing a standard 0.18-mum CMOS process, a receiver frontend and a local oscillator (LO) module are implemented for RF applications at the 24-GHz industrial, scientific, medical band. The proposed frontend is composed of a three-stage low-noise amplifier, a down-conversion mixer, and IF amplifiers. With an IF frequency of 4.82 GHz, the fabricated circuit demonstrates a conversion gain of 28.4 dB and a noise figure of 6.0 dB while maintaining an input return loss better than 14 dB. The measured P in - 1dB and IIP3 of the receiver frontend are -23.2 and -13.0 dBm, respectively. In addition, a circuit module, which generates the required dual down-conversion LO signals, is also included in this study. The proposed LO generator consists of a 19-GHz low-phase-noise voltage-controlled oscillator (VCO), a 4 : 1 frequency divider, and a quadrature phase-tuning circuit. From the measurement results, the VCO exhibits a tuning range of 850 MHz and a phase noise of -110 dBc/Hz at 1-MHz offset frequency. Operated at a supply voltage of 1.8 V, the current consumptions for the receiver frontend and the LO generator are both 30 mA.

Multitone Fast Frequency-Hopping Synthesizer for UWB Radio

A fast frequency-hopping six-band local oscillator signal generator is described in this paper. Targeted for a Wi-Media ultra-wideband radio transceiver, it offers operation in mandatory band group 1 and in extensional band group 3. The circuit entity consists of three parallel phase-locked loops (PLLs), each including two voltage-controlled oscillators, one per band group, and a signal multiplexer for fast frequency selection. A broadband poly-phase RC filter is used for in-phase/quadrature generation. Furthermore, the synthesizer generates the clock signal for analog-to-digital converters by mixing the signals from the first and third PLL. The circuit was fabricated in a 0.13- mum CMOS process and it consumes 32 mA from a 1.2-V supply. It achieves 2-ns frequency settling time with a 3-MHz hopping rate.

A dual-b and RF front-end of direct conversion receiver for wireless CDMA cellular phones with GPS capability

A highly integrated direct conversion receiver for cellular code division multiple access (CDMA) and GPS applications is successfully developed using a 0.5-/spl mu/m SiGe BiCMOS technology. The receiver consists of two low-noise amplifiers (LNAs), a dual-band mixer, two voltage-controlled oscillators (VCOs), a local-oscillator signal generation block, and channel filters. The CDMA LNA achieves a noise figure of 1.3 dB, an input-referred third-order intercept point (IIP3) of 10.9 dBm, and a gain of 15.3 dB with a current consumption of 9.8 mA in the high-gain mode. The mixer for the CDMA mode achieves an uncalibrated input-referred second-order intercept point of 53.7 dBm, an IIP3 of 6.4 dBm, a noise figure of 7.2 dB and a voltage gain of 37.2 dB. The phase noise of the CDMA VCO is approximately -133 dBc/Hz at a 900-kHz offset from a 1.762-GHz operating frequency. It exceeds all the CDMA requirements when tested on a handset.

A 5-GHz direct-conversion CMOS transceiver

A CMOS transceiver fully compliant with IEEE 802.11a in the unlicensed national information infrastructure (UNII) band (5.15-5.35 GHz) achieves a receiver sensitivity of -5 dBm for 64-QAM (quadrature amplitude modulation) with an error vector magnitude (EVM) of -29.3 dB. A single-sideband mixing technique for local-oscillator signal generation avoids frequency pulling. Realized in 0.18-μm CMOS and operating from 1.8-V power supply, the design consumes 171 mW in receive mode and 135 mW in transmit mode while occupying less than 13 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .

Miniaturized artificial-transmission-line monolithic millimeter-wave frequency doubler

Millimeter-wave signals are typically generated by frequency multiplication in modern single-chip or multichip module (MCM) systems. Consequently, the multiplication efficiency, spurious rejection, and size of the frequency multiplier ultimately limit the integration level and cost of these systems. This paper points to the size reduction of millimeter-wave frequency doublers by evaluating artificial transmission lines (ATL's) as a means to minimize the size of the low-impedance shunt stubs. As a result, we developed a 40-GHz frequency doubler, which used only 0.6-mm/sup 2/ area on a monolithic microwave integrated circuit. Despite the area minimization, the doubler exhibited state-of-the-art conversion loss of 1 dB over 10% bandwidth and rejected the fundamental frequency signal by more than 20 dB over 25% bandwidth. Reported herein is the novel simulation of the frequency doubler with active harmonic loads. Included in this paper are theoretical evaluation and simulation of ATL's with models for lumped components and verification of the results by electromagnetic simulation. Due to the high efficiency, low area requirement, and over 20-dB rejection of the fundamental signal, this miniaturized ATL frequency doubler can be used as a building block in the generation of local-oscillator signals in single-chip and MCM millimeter-wave systems.

Local Oscillator Generation Circuit for Direct Conversion Transmitter

In this paper a fully monolithic on-chip local oscillator signal generation circuit is presented for eliminating the negative effect of coupling between bond-wires, package pins and output and input lines of the power amplifier output to the local oscillator input for direct conversion transmitters. The proposed circuit generates the local oscillator signal at frequencies 1710–1785 GHz which is harmonically uncorrelated from two input signals at 464 MHz and 1792–2088 MHz. The required building blocks are a frequency divider, a mixer and an active band-pass filter. Fully monolithic high frequency band-pass filters have not been available until recently, and the designed circuit is in fact one of the first applications reported for MMIC active filters in cellular phones. The circuit is designed with a 0.5 μm GaAs MESFET technology and the performance is verified with on-chip measurements.