A 47 GHz Cross-Coupled VCO Employing High- Island-Gate Varactor for Phase Noise Reduction

A 47 GHz $LC$ cross-coupled voltage controlled oscillator (VCO) employing the high-$Q$ island-gate varactor (IGV) based on a 0.13 $mu{rm m}$ RFCMOS technology is reported in this work. To verify the improvement in the phase noise, two otherwise identical VCOs, each with an IGV and a conventional multi-finger varactor, were fabricated and the phase noise performance was compared. With $V_{DD}$ of 1.2 V and core power consumption of 3.86 mW, the VCOs with the IGV and the multi-finger varactor have a phase noise of $-$95.4 dBc/Hz and $-$91.4 dBc/Hz respectively, at 1 MHz offset, verifying the phase noise reduction with the introduction of the high-$Q$ IGV. The VCO with IGV exhibited an output power of around $-$15 dBm, leading to a FoM of $-$182.9 dBc/Hz and a tuning range of 3.35% (45.69 to 47.22 GHz).      

Integrated Al O :Er Zero-Loss Optical Amplifier and Power Splitter With 40-nm Bandwidth

A combined planar lossless optical amplifier and 1 $,times,$2 power splitter device has been realized in Al$_2$ O$_3$:Er$^{3+}$ on silicon. Net internal gain was measured over a wavelength range of 40 nm across the complete telecom $C$ -band (1525–1565 nm). Calculations predict net gain in a combined amplifier and 1$,times,$ 4 power splitter device over the same wavelength range for a total injected pump power as low as 30 mW.      

Planar -Band 4 4 Nolen Matrix in SIW Technology

In this paper, a 4$,times,$ 4 Nolen matrix beam-forming network for multibeam antenna applications is designed and demonstrated at 12.5-GHz center frequency. The structure is implemented using substrate integrated waveguide (SIW) technology for its attractive advantages including compact size, low loss, light weight, and planar form well suitable for high-density integration with other microwave and millimeter-wave planar integrated circuits. SIW cruciform couplers are used as fundamental building blocks for their wide range of coupling factors and their specific topology well adapted to the serial feeding topology of a Nolen matrix. The network performances are investigated over a 500-MHz frequency bandwidth ranging from 12.25 to 12.75 GHz. The matrix definition based on SIW cruciform couplers is similar to its microstrip counterpart in terms of coupling factors and phase delays. The whole network is fabricated. Measured results are in good agreement with the theoretical predictions, thus validating the proposed design concept. Using this matrix with a four radiating elements array antenna enables us to investigate the impact of the proposed matrix on the beam pointing angles versus frequency.      

A Dual-Band Self-Oscillating Mixer for -Band and -Band Applications

A self-oscillating mixer that employs both the fundamental and harmonic signals generated by the oscillator subcircuit in the mixing process is experimentally demonstrated. The resulting circuit is a dual-band down-converting mixer that can operate in $C$ -band from 5.0 to 6.0 GHz, or in $X$-band from 9.8 to 11.8 GHz. The oscillator uses active superharmonic coupling to enforce the quadrature relationship of the fundamental outputs. Either the fundamental outputs of the oscillator or the second harmonic oscillator output signals that exists at the common-mode nodes are connected to the mixer via a set of complementary switches. The mixer achieves a conversion gain between 5–12 dB in both frequency bands. The output 1-dB compression points for both modes of the mixer are approximately $-{hbox{5 dBm}}$ and the output third-order intercept point for $C$ -band and $X$ -band operation are 12 and 13 dBm, respectively. The integrated circuit was fabricated in 0.13-$mu {hbox{m}}$ CMOS technology and measures ${hbox{0.525 mm}}^{2}$ including bonding pads.      

Generating 4 20 GHz and 4 40 GHz Pulse Trains From a Single 10-GHz Mode-Locked Laser Using a Tunable Planar Lightwave Circuit

We demonstrate a tunable pulse repetition rate multiplier using a silica-based planar lightwave circuit (PLC). The PLC is a six-stage lattice-form Mach–Zehnder interferometer which can be tuned thermally to generate 20- and 40-GHz output pulse trains from a 10-GHz input. We use a nonlinear optical loop mirror as a wavelength converter to perform intensity-to-field conversion to eliminate pulse-to-pulse phase fluctuations in the higher-rate output pulse trains. Moreover, we use wavelength multicasting (simultaneous wavelength conversion) to generate multiple pulse trains (4$,times,$ 20 GHz and 4$,times,$ 40 GHz in the example shown here) from a single 10-GHz input.      

LMS-Based Noise Leakage Calibration of Cascaded Continuous-Time Modulators

In cascaded $DeltaSigma$ modulators (DSMs), the quantization noise of the earlier stage leaks to the output unless completely cancelled by the digital noise cancellation filter (NCF). The noise leakage is worse in the continuous-time (CT) implementation due to the poorly controlled time constant of the analog loop filter. A parameter-based continuous-time to discrete-time transform is developed to get an exact digital NCF, and the analog filter time constant is calibrated to match with the digital NCF. A binary pulse tone is injected into the quantizer to detect the filter time-constant error, and eliminated by zero-forcing its residual power based on the adaptive least-mean-square (LMS) algorithm. A 2-1-1 cascaded CT-DSM prototype in 0.18-$mu{hbox {m}}$ CMOS demonstrates that the spectral density of the leaked noise is lower than 10 ${rm nV}/surd{hbox {Hz}}$ after the capacitors in the Gm-C loop filters are trimmed with 1.1% step. With a 1- ${rm V}_{rm pp}$ full-scale input, it achieves a dynamic range of 68$~$ dB within 18-MHz bandwidth at an over-sampling ratio of 10. The analog core and the digital logic occupy 1.27 ${hbox {mm}}^{2}$, and consume 230 mW at 1.8 V.      

New Miniaturized Dual-Mode Dual-Band Ring Resonator Bandpass Filter With Microwave -Sections

A new miniaturized dual-mode dual-band ring resonator bandpass filter is implemented by a cascade of several microwave $C$-sections. Each $C$-section is used to substitute a transmission line section of designated electrical length. Through proper design of input/output coupling configuration, two transmission zeros can be created on both sides of each passband. Two circuits with four and six microwave $C$-sections are fabricated for confirmation. They occupy less than 30% of the area of a traditional ring resonator filter. Measured responses agree very well with the simulation.      

A 0.7- m BiCMOS Electrostatic Energy-Harvesting System IC

Self-powered microsystems like wireless microsensors and biomedical implants derive power from in-package minibatteries that can only store sufficient energy to sustain the system for a short life. The environment, however, is a rich source of energy that, when harnessed, can replenish the otherwise exhausted battery. The problem is harvesters generate low power levels and the electronics required to transfer the energy to charge a battery can easily demand more than the power produced. This paper presents how a $1times 1~{hbox {mm}}^{2}$ 0.7-$mu{hbox {m}}$ BiCMOS vibration-supplied electrostatic energy-harvesting system IC produces usable energy. The IC charges and holds the voltage across a vibration-driven variable capacitor $C_{VAR}$ so that ambient kinetic energy can induce $C_{VAR}$ to generate current into the battery when capacitance decreases, as the plates separate. The precharger, harvester, monitoring, and control microelectronics draw enough power to operate, yet allow the system to yield (experimentally) 1.27, 2.14, and 2.87 nJ per vibration cycle for battery voltages at 2.7, 3.5, and 4.2 V, which at 30 Hz produce 38.1, 64.2, and 86.1 nW. Experiments further show that the harvester system prototype charges $1~mu {rm F}$ (emulating a small thin-film Li Ion) from 3.5 to 3.81 V in 35 s.      

A 74.8 mW Soft-Output Detector IC for 8 8 Spatial-Multiplexing MIMO Communications

In this paper, VLSI implementation of a configurable, soft-output MIMO detector is presented. The proposed chip can support up to 8 $, times ,$8 64-QAM spatial multiplexing MIMO communications, which surpasses all reported MIMO detector ICs in antenna number and modulation order. Moreover, this chip provides configurable antenna number from 2$,times,$ 2 up to 8$,times,$ 8 and modulation order from QPSK to 64-QAM. Its outputs include bit-wise log likelihood ratios (LLRs) and a candidate list, making it compatible with powerful soft-input channel decoders and iterative decoding system. The MIMO detector adopts a novel sphere decoding algorithm with high decoding efficiency and superior error rate performance, called modified best-first with fast descent (MBF-FD). Moreover, a low-power pipelined quad-dual-heap (quad-DEAP) circuit for efficient node pool management and several circuit techniques are implemented in this chip. When this chip is configured as 4$, times ,$4 64-QAM and 8$, times ,$ 8 64-QAM soft-output MIMO detectors, it achieves average throughputs of 431.8 Mbps and 428.8 Mbps with only 58.2 mW and 74.8 mW respective power consumption and reaches 10$^{-5}$ coded bit error rate (BER) at signal-to-noise ratio (SNR) of 24.2 dB and 22.6 dB, respectively.      

A Fully-Differential Complementary Hartley VCO in 0.18 m CMOS Technology

In this letter, a new complementary Hartley (C-Hartley) voltage controlled oscillator (VCO) with fully differential outputs is proposed, in which the self-biasing configuration is introduced to solve the biasing difficulty of a Hartley VCO by employing a five-port transformer. The proposed C-Hartley VCO with the center frequency of 5.6 GHz is implemented in a 1P6M 0.18 $mu$m CMOS process. The measurement result shows that the phase noise is ${-}123.6$ dBc/Hz at 1 MHz offset frequency, while dissipating 6.5 mA from 1.6 V supply with the FOM of ${-}188.5$ dBc.      

Low Phase Noise Differential Vackar VCO in 0.18 CMOS Technology

In this letter, we present the measured performance of a differential Vackar voltage-controlled oscillator (VCO) implemented for the first time in CMOS technology. The Vackar VCO provided good isolation between the LC tank and the loss-compensating active circuit; thus, excellent frequency stability was achieved over the frequency tuning range. The Vackar VCO was implemented using nMOS transistors and an LC tank in a 0.18 $mu{rm m}$ RF CMOS process. The oscillation frequency ranged from 4.85 to 4.93 GHz. The measured phase noise of the Vackar VCO at 1 MHz offset was $-124.9 ~{rm dB}/{rm Hz}$ at 4.9 GHz with a figure-of-merit (FOM) of $-188 ~{rm dBc}/{rm Hz}$.      

A 10-GHz Optoelectronic Oscillator at 1.1 m Using a Single-Mode VCSEL and a Photonic Crystal Fiber

We report a self-starting optoelectronic oscillator operating at 1.1 $mu{hbox {m}}$ that uses a gain-switched vertical-cavity surface-emitting laser (VCSEL) and a single-mode photonic crystal fiber. The modulation bandwidth and sidemode suppression ratio of the VCSEL were 7.2 GHz and more than 50 dB, respectively. A 10-GHz 11.5-ps optical pulse train with a timing jitter of 0.9 ps was successfully generated.      

Analysis and Design of a CMOS UWB LNA With Dual- -Branch Wideband Input Matching Network

A wideband low-noise amplifier (LNA) based on the current-reused cascade configuration is proposed. The wideband input-impedance matching was achieved by taking advantage of the resistive shunt–shunt feedback in conjunction with a parallel LC load to make the input network equivalent to two parallel $RLC$-branches, i.e., a second-order wideband bandpass filter. Besides, both the inductive series- and shunt-peaking techniques are used for bandwidth extension. Theoretical analysis shows that both the frequency response of input matching and noise figure (NF) can be described by second-order functions with quality factors as parameters. The CMOS ultra-wideband LNA dissipates 10.34-mW power and achieves ${ S}_{11}$ below $-$8.6 dB, ${ S}_{22}$ below $-$10 dB, ${ S}_{12}$ below $-$26 dB, flat ${ S}_{21}$ of 12.26 $pm$ 0.63 dB, and flat NF of 4.24 $ pm$ 0.5 dB over the 3.1–10.6-GHz band of interest. Besides, good phase linearity property (group-delay variation is only $pm$22 ps across the whole band) is also achieved. The analytical, simulated, and measured results agree well with one another.      

A Wide Tuning Range 69 GHz Push-Push VCO Using 0.18 CMOS Technology

A wide tuning range V-band push-push CMOS voltage controlled oscillator (VCO) is proposed in this study. A new core complementary Colpitts structure was adopted in a 0.18 $mu{rm m}$ CMOS process to reduce dc power consumption and to improve tuning range owing to the reduction weighting of FET induced capacitance of L-C tank. The designed VCO oscillates from 64.2 to 69.4 GHz with a 5.2 GHz tuning range under a control voltage range of 1.2 V. The measured phase noise at 1 MHz offset is $-76.23~ {rm dBc}/{rm Hz}$ at 69.39 GHz. The power consumption of the VCO core is only 27.52 mW.      

Optical Demultiplexing of 320 Gb/s to 8 40 Gb/s in Single Parametric Gate

In this paper, we report the experimental demonstration of 320 Gb/s demultiplexing to eight simultaneous always-on 40 Gb/s tributaries with near-zero latency. The single-channel, single-polarization 320 Gb/s optical-time-division-multiplexed signal was processed by a copy-and-sample-all architecture. 1-to-8 wavelength multicasting over more than 10 THz of bandwidth was achieved in a self-seeded two-pump parametric amplifier, and was followed by a single gate, multicolored sampling with equalized response over more than 20 THz. The single gate operation allows for truly scalable real-time processing while avoiding the complexity of parallel pipelines processing. Error-free performance was measured over all extracted 40 Gb/s tributaries with less than 4 dB power penalty compared to conventional single tributary gating.      

Experimental 2.5-Gb/s QPSK WDM Phase-Modulated Radio-Over-Fiber Link With Digital Demodulation by a -Means Algorithm

Highest reported bit rate of 2.5 Gb/s for optically phase-modulated radio-over-fiber (RoF) link, employing digital coherent detection, is demonstrated. Demodulation of 3$,times,$ 2.5 Gb/s quadrature phase-shift-keying modulated wavelength-division-multiplexed RoF channels is achieved after 79 km of transmission through deployed fiber. Error-free performance (bit-error rate corresponding to $10^{{-}4}$) is achieved using a digital coherent receiver in combination with a $K$-means algorithm for radio-frequency phase recovery.      

Highly Spectrally Efficient DWDM Transmission at 7.0 b/s/Hz Using 8 65.1-Gb/s Coherent PDM-OFDM

In this paper, we discuss the realization of wavelength-division multiplexing (WDM) transmission at high spectral efficiency. For this experiment, coherent polarization-division multiplexing--orthogonal frequency-division multiplexing (PDM-OFDM) is used as a modulation format. PDM-OFDM uses training symbols for channel estimation. This makes OFDM easily scalable to higher level modulation formats as channel estimation is realized with training symbols that are independent of the constellation size. Furthermore, because of its well-defined spectrum OFDM requires only a small guard band between WDM channels. The dependence of the number of OFDM subcarriers is investigated with respect to the interchannel linear crosstalk. At a constant data rate the number of OFDM subcarriers is estimated to achieve lower linear crosstalk in order to achieve higher spectral efficiency. We then experimentally demonstrate dense WDM (DWDM) transmission with 7.0-b/s/Hz net spectral efficiency using 8 $,times,$65.1-Gb/s coherent PDM-OFDM signals with 8-GHz WDM channel spacing utilizing 32-quadrature-amplitude-modulation subcarrier modulation. Successful transmission is achieved over 240 km standard single-mode fiber (SSMF) spans with hybrid erbium-doped fiber amplifiers/Raman amplification.      

An 11.1 mW 42 MS/s 10 b ADC With Two-Step Settling in 0.18 m CMOS

A pipelined analog-to-digital converter (ADC) uses switched-capacitor stages that settle in two steps that occur sequentially in time. The first step of settling places charge onto the load capacitance using charge pumps, and the second fulfills the settling requirements using typical negative feedback around an operational amplifier. Hence, the design combines the efficiency of a fast charge-transfer phase with the gain and noise-immunity advantages of amplifier-driven settling. Improved conversion efficiency results from a higher ratio of current delivered to the load to that consumed in static biasing. Additional circuitry constrains critical amplifier node voltages during the charge transfer, facilitating a graceful transition to amplifier-driven settling. The two-step settling technique is demonstrated in a 2.5 bit/stage 10-bit pipelined ADC that consumes 11.1 mW while sampling a 21.3 MHz input signal at 42 MS/s. The resulting SNDR is 55.6 dB $rm (ENOB = 8.94)$ and the SFDR is 67.5 dB.      

Low-Loss 4–6-GHz Tunable Filter With 3-Bit High-$Q$ Orthogonal Bias RF-MEMS Capacitance Network

This paper presents a low-loss 4-6-GHz 3-bit tunable filter on a quartz substrate using a high-Q 3-bit orthogonal bias RF microelectromechanical systems capacitance network. Detailed design equations for the capacitively loaded coupled lambda/2 resonators and with capacitive external coupling and source-load impedance loading are discussed. Measurements show an unloaded Q of 85-170, an insertion loss of 1.5-2.8 dB, and a 1-dB bandwidth of 4.35plusmn0.35% at 4-6 GHz. The measured third-order intermodulation intercept point and 1-dB power compression point at 5.91 GHz are > 40 and 27.5 dBm, respectively. The unloaded Q can be improved to 125-210 with the use of a thicker bottom electrode. To our knowledge, this is the highest Q tunable planar filter to date at this frequency range.     

High Microwave-Noise Performance of AlGaN/GaN MISHEMTs on Silicon With Gate Insulator Grown by ALD

High microwave-noise performance is realized in AlGaN/GaN metal–insulator semiconductor high-electron mobility transistors (MISHEMTs) on high-resistivity silicon substrate using atomic-layer-deposited (ALD) $hbox{Al}_{2}hbox{O}_{3}$ as gate insulator. The ALD $hbox{Al}_{2}hbox{O}_{3}/hbox{AlGaN/GaN}$ MISHEMT with a 0.25- $muhbox{m}$ gate length shows excellent microwave small signal and noise performance. A high current-gain cutoff frequency $f_{T}$ of 40 GHz and maximum oscillation frequency $f_{max}$ of 76 GHz were achieved. At 10 GHz, the device exhibits low minimum-noise figure $(hbox{NF}_{min})$ of 1.0 dB together with high associate gain $(G_{a})$ of 10.5 dB and low equivalent noise resistance $(R_{n})$ of 29.2 $Omega$. This is believed to be the first report of a 0.25-$muhbox{m}$ gate-length GaN MISHEMT on silicon with such microwave-noise performance. These results indicate that the AlGaN/GaN MISHEMT with ALD $hbox{Al}_{2}hbox{O}_{3}$ gate insulator on high-resistivity Si substrate is suitable for microwave low-noise applications.