A Compact Four-Wavelength Quantum-Cascade Laser Source

A four-wavelength quantum-cascade (QC) laser source that operates using a single current channel is presented. The source includes two different heterogeneous cascade QC lasers, one with emission wavelengths of 7.0 $mu{hbox {m}}$ and 11.2 $mu{hbox {m}}$, and the other with 8.7 $mu{hbox {m}}$ and 12.0 $mu{hbox {m}}$ . For 3.0-mm and 3.5-mm cavity lengths, QC lasers with emission wavelengths of 8.7, 11.2, and 12.0 $mu{hbox {m}}$ have threshold current densities within less than a factor of 2, which allows them to be conveniently driven in series by a single current source.      

17 GHz RF Front-Ends for Low-Power Wireless Sensor Networks

A 17 GHz low-power radio transceiver front-end implemented in a 0.25 $mu{hbox {m}}$ SiGe:C BiCMOS technology is described. Operating at data rates up to 10 Mbit/s with a reduced transceiver turn-on time of 2 $mu{hbox {s}}$, gives an overall energy consumption of 1.75 nJ/bit for the receiver and 1.6 nJ/bit for the transmitter. The measured conversion gain of the receiver chain is 25–30 dB into a 50 $Omega$ load at 10 MHz IF, and noise figure is 12 $pm$0.5 dB across the band from 10 to 200 MHz. The 1-dB compression point at the receiver input is $-$37 dBm and ${hbox{IIP}}_{3}$ is $-$25 dBm. The maximum saturated output power from the on-chip transmit amplifier is $-$1.4 dBm. Power consumption is 17.5 mW in receiver mode, and 16 mW in transmit mode, both operating from a 2.5 V supply. In standby, the transceiver supply current is less than 1 $mu{hbox {A}}$.      

Enhanced Transmission in a Fiber-Coupled Au Stripe Waveguide System

We experimentally demonstrated the enhanced transmission in a fiber-coupled Au stripe waveguide system using a linearly tapered (LT) structure at a telecommunication wavelength of 1.55 $mu{hbox {m}}$. The LT structure consists of two 100- $mu{hbox {m}}$-long tapered regions connecting various widths of input and output waveguides with a waist region. The lowest insertion loss of the 1-cm-long LT-Au stripe waveguide is $sim$4.3 dB, when it has 6-$mu{hbox {m}}$ -wide input and output waveguides and a 4- $mu{hbox {m}}$-wide waist waveguide. The insertion loss is reduced by $sim$ 2 dB compared to the 4-$mu{hbox {m}}$-wide and 1-cm-long straight Au stripe waveguide, which is achieved by decreasing the coupling loss. The losses of the LT region, which has a tapered angle of less than 0.3$^{circ}$ between the input–output waveguides and the waist waveguide, are smaller than 0.4 dB. We showed that the insertion loss of the Au stripe waveguide can be reduced by introducing the LT structure, which can also provide efficient mode conversion.      

InGaAs/GaAs 0.98- $mu{hbox {m}}$ Low-Divergence Central-Lobe Semiconductor Lasers With $delta$ -Doped Resonant Tunneling Quantum Wells

In this paper, we describe a new structure design for producing low-threshold, high-efficiency, and high-brightness 0.98-$mu{hbox {m}}$ lasers. In this structure, we incorporated a self-discriminating weak optical confinement asymmetrical waveguide coupled to passive waveguides, and an active region based on three InGaAs quantum wells (QWs) coupled to Te n-type $delta$-doping. Optimized coupling between the $delta$-doping and the three QWs, together with waveguide optimization and doping profile optimization, yields $J_{rm th}=98 {hbox {A/cm}}^{2}$ per QW, ${T}_{0}=80;^{circ}hbox{C}$, and a far-field central lobe angle of $sim 10^{circ}$.      

High Heat Flux Two-Phase Cooling in Silicon Multimicrochannels

This paper presents performances of two-phase cooling of a chip at very high heat flux with refrigerant R236fa in a silicon multimicrochannel heat sink. This heat sink was composed of 134 parallel channels, 67 $mu {hbox {m}}$ wide, 680 $mu {hbox {m}}$ high, and 20 mm long, with 92-$mu {hbox {m}}$ -thick fins separating the channels. The base heat flux was varied from 3 to 255 ${hbox {W/cm}}^{2}$ , the volume flow rate from 0.18 to 0.67 l/min, and the exit vapor quality from 0 to 80%. The working pressure and saturation temperature were set at 273 kPa and 25 $^{circ}{hbox {C}}$, respectively. The present database includes 1040 local heat transfer coefficients. The base temperature of the chip could be maintained below 52 $^{circ}{hbox {C}}$ while dissipating 255 ${hbox {W/cm}}^{2}$ with 10 $~^circ{hbox {C}}$ of inlet subcooling and 90 kPa of pressure drop. A comparison of the respective performances with an extrapolation of the present results shows that two-phase cooling should be able to cool the chip 13 K lower than liquid cooling for the same pumping power at a base heat flux of 350 ${hbox {W/cm}}^{2}$.      

Near-Stoichiometric Ti : LiNbO$_{3}$ Strip Waveguides Fabricated by Standard Ti Diffusion and Post-VTE

We report near-stoichiometric (NS) Ti : LiNbO$_{3}$ waveguides fabricated by indiffusion of 4-, 5-, 6-, 7- $mu{hbox {m}}$-wide 120-nm-thick Ti-strips at 1060 $^{circ}hbox{C}$ for 10 h into a congruent $hbox{LiNbO}_{3}$ (i.e., standard Ti diffusion procedure) and post-vapour-transport-equilibration (VTE) treatment at 1100 $^{circ}hbox{C}$ for 5 h. These waveguides are NS and single-mode at 1.5 $mu{hbox {m}}$, and have a loss of 1.0/0.8 dB/cm for the TM/TE mode. In the width/depth direction of the waveguide, the mode field follows a Gauss/Hermite–Gauss profile, and the Ti profile follows a sum of two error functions/a Gauss function. The post-VTE resulted in increase of diffusion width/depth by 2.0/1.0 $mu{hbox {m}}$. A two-dimensional refractive index profile in the guiding layer is suggested.      

Low-Threshold Strained Quantum-Well GaSb-Based Lasers Emitting in the 2.5- to 2.7-$mu$ m Wavelength Range

GaInAsSb–GaSb strained quantum-well (QW) ridge waveguide diode lasers emitting in the wavelength range from 2.51 to 2.72 $ mu{hbox {m}}$ have been grown by molecular beam epitaxy. The devices show ultralow threshold current densities of 44 $hbox{A}/{hbox {cm}}^{2}$ (${L}rightarrow infty $) for a single QW device at 2.51 $ mu{hbox {m}}$, which is the lowest reported value in continuous-wave operation near room temperature (15 $^{circ}hbox{C}$) at this wavelength. The devices have an internal loss of 3 ${hbox {cm}}^{-1}$ and a characteristic temperature of 42 K. By using broader QWs, wavelengths up to 2.72 $mu{hbox {m}}$ could be achieved.      

A Noise-Coupled Time-Interleaved Delta-Sigma ADC With 4.2 MHz Bandwidth, ${-}$ 98 dB THD, and 79 dB SNDR

This paper describes a wideband high-linearity $Delta Sigma $ ADC. It uses noise coupling combined with time interleaving. Two versions of a two-channel time-interleaved noise-coupled $Delta Sigma $ ADC were realized in a 0.18- $mu{hbox {m}}$ CMOS technology. Noise coupling between the channels increases the effective order of the noise-shaping loops, provides dithering, and prevents tone generation in all loops. Time interleaving enhances the effects of noise coupling. Using a 1.5 V supply, the device achieved excellent linearity (${rm SFDR} > {hbox {100~dB}}$, ${rm THD}= -{hbox {98~dB}}$) and an SNDR of 79 dB in a 4.2 MHz signal band.      

Experimental Demonstration of Deeply-Etched SiO$_{2}$ Ridge Optical Waveguides and Devices

Deeply-etched ${hbox{SiO}}_{2}$ optical ridge waveguides are fabricated and characterized. A detailed discussion of the fabrication process (especially for the deep etching process) is presented. The measured propagation losses for the fabricated waveguides with different core widths range from $0.33sim {hbox {0.81}}~{hbox {dB}}/{hbox {mm}}$. The loss is mainly caused by the scattering due to the sidewall roughness. The losses in bending sections are also characterized, which show the possibility of realizing a small bending radius (several tens of microns). 1 $,times {rm N}$ ( ${rm N}=2$, 4, 8) multimode interference couplers based on the deeply-etched ${hbox{SiO}}_{2}$ ridge waveguide are also fabricated and show fairly good performances.      

Q-Band pHEMT and mHEMT Subharmonic Gilbert Upconversion Mixers

This letter makes a comparison between Q-band 0.15 $mu{rm m}$ pseudomorphic high electron mobility transistor (pHEMT) and metamorphic high electron mobility transistor (mHEMT) stacked-LO subharmonic upconversion mixers in terms of gain, isolation and linearity. In general, a 0.15 $mu{rm m}$ mHEMT device has a higher transconductance and cutoff frequency than a 0.15 $mu{rm m}$ pHEMT does. Thus, the conversion gain of the mHEMT is higher than that of the pHEMT in the active Gilbert mixer design. The Q-band stacked-LO subharmonic upconversion mixers using the pHEMT and mHEMT technologies have conversion gain of $-$7.1 dB and $-$0.2 dB, respectively. The pHEMT upconversion mixer has an ${rm OIP}_{3}$ of $-$12 dBm and an ${rm OP}_{1 {rm dB}}$ of $-$24 dBm, while the mHEMT one shows a 4 dB improvement on linearity for the difference between the ${rm OIP}_{3}$ and ${rm OP}_{1 {rm dB}}$. Both the chip sizes are the same at 1.3 mm $times$ 0.9 mm.      

A Merged CMOS Digital Near-End Crosstalk Canceller and Analog Equalizer for Multi-Lane Serial-Link Receivers

A digital near-end crosstalk (NEXT) canceller merged with an analog equalizer for multi-lane serial-link receivers has been realized in 0.13 $mu{hbox {m}}$ CMOS technology. By applying the proposed sign-sign block least-mean-square (SSB-LMS) circuit, a 5 Gb/s pseudorandom binary sequence (PRBS) of 2 $^{31}-$1 suffered from both the channel loss and NEXT over 10- and 20-inch FR4 traces with the width of 5-mil and the spacing of 7-mil is successfully equalized. The measured bit error rate (BER) is 10$^{-12}$ and the measured maximum peak-to-peak jitter is 49.7 ps. This chip occupies 0.56 $,times,$0.76 $ {hbox {mm}}^{2}$ and the whole circuit including buffers consumes 177 mW from a 1.2 V supply.      

Adaptive On-Chip Power Supply With Robust One-Cycle Control Technique

In this paper, an integrated adaptive-output switching converter is proposed. The design employs a one-cycle control for fast line regulation and a single outer loop for tight load regulation and fine tuning. A switched-capacitor integrator is introduced to the one-cycle control to obtain positive integration with a single positive power supply, allowing a standard low-cost CMOS fabrication process. To improve the efficiency, a dynamic loss control technique is presented. The converter was designed and fabricated with 0.35 $mu{hbox{m}}$ N-well CMOS process. With a supply voltage of 3 V, a voltage ripple of less than $pm$20 mV is measured. The maximum efficiency is 92% with a load power of 475 mW. The converter exhibits a tracking speed of 23.75 $mu{hbox{s/V}}$ for both start-up and reference voltage transitions. The recovery time for a 20% load change is approximately 9.5 $mu{hbox{s}}$.      

A Sub-0.2$^{circ}/$ hr Bias Drift Micromechanical Silicon Gyroscope With Automatic CMOS Mode-Matching

This paper describes a system architecture and CMOS implementation that leverages the inherently high mechanical quality factor (Q) of a MEMS gyroscope to improve performance. The proposed time domain scheme utilizes the often-ignored residual quadrature error in a gyroscope to achieve, and maintain, perfect mode-matching (i.e., $sim$0 Hz split between the high-Q drive and sense mode frequencies), as well as electronically control the sensor bandwidth. A CMOS IC and control algorithm have been interfaced with a 60 $mu{hbox {m}}$ thick silicon mode-matched tuning fork gyroscope $({rm M}^{2}mathchar"707B {rm TFG})$ to implement an angular rate sensing microsystem with a bias drift of 0.16$^{circ}/{hbox{hr}}$. The proposed technique allows microsystem reconfigurability—the sensor can be operated in a conventional low-pass mode for larger bandwidth, or in matched mode for low-noise. The maximum achieved sensor Q is 36,000 and the bandwidth of the microsensor can be varied between 1 to 10 Hz by electronic control of the mechanical frequencies. The maximum scale factor of the gyroscope is 88 ${hbox{mV}}/^{circ}/{hbox{s}}$ . The 3$~$ V IC is fabricated in a standard 0.6 $ mu{hbox {m}}$ CMOS process and consumes 6 mW of power with a die area of 2.25 ${hbox {mm}}^{2}$.      

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.      

A $Q$ -Band Four-Element Phased-Array Front-End Receiver With Integrated Wilkinson Power Combiners in 0.18-$mu{{hbox{m}}}$ SiGe BiCMOS Technology

A four-element phased-array front-end receiver based on 4-bit RF phase shifters is demonstrated in a standard 0.18- $mu{{hbox{m}}}$ SiGe BiCMOS technology for $Q$-band (30–50 GHz) satellite communications and radar applications. The phased-array receiver uses a corporate-feed approach with on-chip Wilkinson power combiners, and shows a power gain of 10.4 dB with an ${rm IIP}_{3}$ of $-$13.8 dBm per element at 38.5 GHz and a 3-dB gain bandwidth of 32.8–44 GHz. The rms gain and phase errors are $leq$1.2 dB and $leq {hbox{8.7}}^{circ}$ for all 4-bit phase states at 30–50 GHz. The beamformer also results in $leq$ 0.4 dB of rms gain mismatch and $leq {hbox{2}}^{circ}$ of rms phase mismatch between the four channels. The channel-to-channel isolation is better than $-$35 dB at 30–50 GHz. The chip consumes 118 mA from a 5-V supply voltage and overall chip size is ${hbox{1.4}}times {hbox{1.7}} {{hbox{mm}}}^{2}$ including all pads and CMOS control electronics.      

A Low-Voltage Mobility-Based Frequency Reference for Crystal-Less ULP Radios

The design of a 100 kHz frequency reference based on the electron mobility in a MOS transistor is presented. The proposed low-voltage low-power circuit requires no off-chip components, making it suitable for application in wireless sensor networks (WSN). After a single-point calibration, the spread of its output frequency is less than 1.1% (3$sigma $) over the temperature range from $-{hbox{22}},^{circ}{hbox{C}}$ to 85$,^{circ}{hbox{C}}$ . Fabricated in a baseline 65$~$nm CMOS technology, the frequency reference circuit occupies 0.11$ hbox{mm}^{2}$ and draws 34 $ muhbox{A}$ from a 1.2 V supply at room temperature.      

A Driving Scheme for Active-Matrix Organic Light-Emitting Diode Displays Based on Current Feedback

This paper presents a method of driving active-matrix organic light-emitting diode (AMOLED) displays with amorphous silicon (a-Si) thin-film transistors (TFTs). By using current feedback, the method effectively compensates for the effect of shift in the threshold voltage $(V_{T})$ of a-Si TFTs on the OLED current. A CMOS transresistance amplifier is used as the column driver to cancel the effect of large parasitic capacitance of data lines. An accelerating pulse is used at the start of the programming cycle to improve the settling at low currents. A detailed analysis has been done to investigate the effect of circuit components on the sensitivity of the OLED current to $V_{T}$ shift and the settling behavior of the circuit. Prototypes of pixel circuits and the transresistance amplifier were fabricated in an a-Si TFT process and a 0.8- $mu{hbox{m}}$ 20-V CMOS technology, respectively. Measurements show less than 5% change in the OLED current for 2.5-V shift in $V_{T}$ of TFTs. Settling times smaller than 50 $mu{hbox{s}}$ were achieved for parasitic capacitances of 50–200 pF and programming currents as small as 200 nA.      

All-Silicon 1.55-$mu$m High-Resolution Photon Counting and Timing

We investigate the performances at 1.55- $mu{hbox{m}}$ wavelength of silicon single photon avalanche diodes (SPADs), demonstrating their suitable applicability in laser characterizations and ultra-sensitive autocorrelation measurements. We investigate the photon detection efficiency and the two-photon absorption process of both lightly doped thick SPADs and heavily doped thin SPADs. Finally, we report the accurate pulse-shape characterization of a 1.55- $mu{hbox{m}}$ pulsed laser by means of a thin silicon SPAD that exploits the best intrinsic time resolution of 25 ps with wide dynamic range and low measurement time.      

An Edge Missing Compensator for Fast Settling Wide Locking Range Phase-Locked Loops

An edge missing compensator (EMC) is proposed to approach the function of an ideal PD with $pm 2 ^{N-1} times 2pi $ linear range with $N$-bit EMC. A PLL implemented with a 9-bit EMC achieves 320 MHz frequency hopping within 10 $~mu{hbox {s}}$ logarithmically which is about 2.4 times faster than the conventional design. The reference spur of the PLL is ${-}{hbox {48.7~dBc}}$ and the phase noise is ${-}hbox{88.31~dBc/Hz}$ at 10 kHz offset with $K_{rm VCO}= -$ 2 GHz/V.      

Soft Glass Equiangular Spiral Photonic Crystal Fiber for Supercontinuum Generation

An equiangular spiral photonic crystal fiber (ES-PCF) design in soft glass is presented that has high nonlinearity ( $gamma>5250 hbox{W}^{-1}cdothbox{km}^{-1}$ at 1064 nm and $gamma>2150 hbox{W}^{-1}cdothbox{km}^{-1}$ at 1550 nm) with a low and flat dispersion (${D}sim {hbox {0.8}} hbox{ps/km}cdothbox{nm}$ and dispersion slope $sim-0.7 hbox{ps/km}cdothbox{nm}^{2}$ at 1060 nm). The design inspired by nature is characterized by a full-vectorial finite element method. The ES-PCF presented improves over the mode confinement of triangular core designs and dispersion control of conventional hexagonal PCF, combining the advantages of both designs; it can be an excellent candidate for generating supercontinuum pumped at 1.06 $mu{hbox {m}}$.