$S$ - and $C$ -Band Ultra-Compact Phase Shifters Based on All-Pass Networks

Ultra-compact phase shifters are presented. The proposed phase-shifting circuits utilize the lumped element all-pass networks. The transition frequency of the all-pass network, which determines the size of the circuit, is set to be much higher than the operating frequency. This results in a significantly small chip size of the phase shifter. To verify this methodology, 5-bit phase shifters have been fabricated in the $S$ - and $C$ -band. The $S$ -band phase shifter, with a chip size of 1.87 mm $,times,$0.87 mm (1.63 mm $^{2}$), has achieved an insertion loss of ${hbox{6.1 dB}} pm {hbox{0.6 dB}}$ and rms phase-shift error of less than 2.8$^{circ}$ in 10% bandwidth. The $C$ -band phase shifter, with a chip size of 1.72 mm $,times,$0.81 mm (1.37 mm $^{2}$), has demonstrated an insertion loss of 5.7 dB $pm$ 0.8 dB and rms phase-shift error of less than 2.3 $^{circ}$ in 10% bandwidth.      

Temperature Compensated Refractometric Biosensor Exploiting Ring Resonators

A temperature compensated refractometric biosensor in polymeric waveguides was demonstrated by integrating a vertically coupled ring resonator with a laterally coupled ring resonator playing the role of monitoring the temperature. The proposed main sensing part was evaluated by observing the concentration of an aqueous glucose solution, and it was found to work decently around room temperature, yielding the sensitivity of ${sim}$120 pm/(g/dL), and the temperature monitoring part offered a temperature sensitivity of $-$172 pm/ $^{circ}$C. With the help of the temperature compensation, the measurement error of the main sensor resulting from the temperature variation was substantially reduced from 1.33 (g/dL)/$^{circ}hbox{C}$ down to 0.03 (g/dL)/$^{circ}hbox{C}$ .      

Compact $S$ -/$Ka$-Band CMOS Quadrature Hybrids With High Phase Balance Based on Multilayer Transformer Over-Coupling Technique

This paper presents compact CMOS quadrature hybrids by using the transformer over-coupling technique to eliminate significant phase error in the presence of low-$Q$ CMOS components. The technique includes the inductive and capacitive couplings, where the former is realized by employing a tightly inductive-coupled transformer and the latter by an additional capacitor across the transformer winding. Their phase balance effects are investigated and the design methodology is presented. The measurement results show that the designed 24-GHz CMOS quadrature hybrid has excellent phase balance within ${pm}{hbox{0.6}}^{circ}$ and amplitude balance less than ${pm} {hbox{0.3}}$ dB over a 16% fractional bandwidth with extremely compact size of 0.05 mm$^{2}$. For the 2.4-GHz hybrid monolithic microwave integrated circuit, it has measured phase balance of ${pm}{hbox{0.8}}^{circ}$ and amplitude balance of ${pm} {hbox{0.3}}$ dB over a 10% fractional bandwidth with a chip area of 0.1 mm$^{2}$ .      

A 300 nW, 15 ppm/$^{circ}$C, 20 ppm/V CMOS Voltage Reference Circuit Consisting of Subthreshold MOSFETs

A low-power CMOS voltage reference was developed using a 0.35 $mu$m standard CMOS process technology. The device consists of MOSFET circuits operated in the subthreshold region and uses no resistors. It generates two voltages having opposite temperature coefficients and adds them to produce an output voltage with a near-zero temperature coefficient. The resulting voltage is equal to the extrapolated threshold voltage of a MOSFET at absolute zero temperature, which was about 745$~$mV for the MOSFETs we used. The temperature coefficient of the voltage was 7 ppm/ $^{circ}$C at best and 15 ppm/$^{circ}$C on average, in a range from ${-}$ 20 to 80$^{circ}$ C. The line sensitivity was 20 ppm/V in a supply voltage range of 1.4–3 V, and the power supply rejection ratio (PSRR) was ${-}$45 dB at 100 Hz. The power dissipation was 0.3 $mu$W at 80$^{circ}$C. The chip area was 0.05 mm$^2$ . Our device would be suitable for use in subthreshold-operated, power-aware LSIs.      

A 0.13 $mu$ m CMOS Quad-Band GSM/GPRS/EDGE RF Transceiver Using a Low-Noise Fractional-N Frequency Synthesizer and Direct-Conversion Architecture

This paper presents a single-chip CMOS quad-band (850/900/1800/1900 MHz) RF transceiver for GSM/GPRS/EDGE applications which adopts a direct-conversion receiver, a direct-conversion transmitter and a fractional-N frequency synthesizer with a built-in DCXO. In the GSM mode, the transmitter delivers 4 dBm of output power with 1$^{circ}$ RMS phase error and the measured phase noise is ${-}$164.5 dBc/Hz at 20 MHz offset from a 914.8$~$MHz carrier. In the EDGE mode, the TX RMS EVM is 2.4% with a 0.5 $~$dB gain step for the overall 36 dB dynamic range. The RX NF and IIP3 are 2.7 dB/ ${-}$12 dBm for the low bands (850/900 MHz) and 3 dB/${-}$ 11 dBm for the high bands (1800/1900 MHz). This transceiver is implemented in 0.13 $mu$m CMOS technology and occupies 10.5 mm$^{2}$ . The device consumes 118 mA and 84 mA in TX and RX modes from 2.8 V, respectively and is housed in a 5$,times,$ 5 mm$^{2}$ 40-pin QFN package.      

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.      

$hbox{TiN/ZrO}_{2}$/Ti/Al Metal–Insulator–Metal Capacitors With Subnanometer CET Using ALD-Deposited $hbox{ZrO}_{2}$ for DRAM Applications

We provide the first report of the structural and electrical properties of $hbox{TiN/ZrO}_{2}$/Ti/Al metal–insulator–metal capacitor structures, where the $hbox{ZrO}_{2}$ thin film (7–8 nm) is deposited by ALD using the new zirconium precursor ZrD-04, also known as Bis(methylcyclopentadienyl) methoxymethyl. Measured capacitance–voltage ($C$– $V$) and current–voltage ( $I$–$V$) characteristics are reported for premetallization rapid thermal annealing (RTP) in $hbox{N}_{2}$ for 60 s at 400 $^{circ}hbox{C}$, 500 $^{circ}hbox{C}$, or 600 $^{ circ}hbox{C}$. For the RTP at 400 $^{circ}hbox{C}$ , we find very low leakage current densities on the order of nanoamperes per square centimeter at a gate voltage of 1 V and low capacitance equivalent thickness values of $sim$ 0.9 nm at a gate voltage of 0 V. The dielectric constant of $ hbox{ZrO}_{2}$ is 31 $pm$ 2 after RTP treatment at 400 $^{circ}hbox{C}$.      

Temperature-Insensitive Dual-Comb Filter Based on Multimode Interference Ti : LiNbO $_{3}$ Waveguide

A temperature-insensitive dual-comb filter has been demonstrated for the first time by multimode interference based on a Ti : LiNbO$_{3}$ channel waveguide. The phase difference between comb filters was about 180 $^{circ}$. We only observed less than ${pm}$0.125-nm variation of the center wavelength of the filter during temperature change from 20 $^{circ}$C to 50 $^{circ}$C. The measured extinction ratio and channel spacing of the comb filter were about ${-}$25 dB and 3.2 THz, respectively.      

180$^{circ}$ and 90$^{circ}$ Phase Shifting Networks With an Octave Bandwidth and Small Phase Errors

A new phase shifting network for both 180 $^{circ}$ and 90 $^{circ}$ phase shift with small phase errors over an octave bandwidth is presented. The theoretical bandwidth is 67% for the 180$^{circ}$ phase bit and 86% for the 90$^{circ}$ phase bit when phase errors are $pm 2^{circ}$. The proposed topology consists of a bandpass filter (BPF) branch, consisting of a LC resonator and two shunt quarter-wavelength transmission lines (TLs), and a reference TL. A theoretical analysis is provided and scalable parameters are listed for both phase bits. To test the theory, phase shifting networks from 1 GHz to 3 GHz were designed. The measured phase errors of the 180$^{circ}$ and the 90$^{circ}$ phase bit are $pm 3.5^{circ}$ and $pm 2.5^{circ}$ over a bandwidth of 73% and 102% while the return losses are better than 18 dB and 12 dB, respectively.      

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.      

Compact In-Fiber Interferometer Formed by Long-Period Gratings in Photonic Crystal Fiber

We reported the design and implementation of an in-fiber Mach–Zehnder interferometer (MZI) based on a pair of long-period gratings (LPGs) written on a photonic crystal fiber (PCF). The LPG was fabricated by using a pulsed CO$_{2}$ laser to carve grooves periodically along the PCF. The MZI relies on the interference between the fundamental core mode and a cladding mode of the PCF. The MZI was further demonstrated as a temperature sensor and a strain sensor. The temperature and strain sensitivities were measured to be 42.4 pm/$^{circ}hbox{C}cdot hbox{m}$ and $-$ 2.6 pm/$mu varepsilon $, respectively. We also fabricated an MZI on a single-mode fiber, which has a temperature sensitivity of 1215.56 pm/( $^{circ}hbox{C}cdot hbox{m}$) and a strain sensitivity of $+$ 0.445 pm/$mu varepsilon $.      

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 36–80 GHz High Gain Millimeter-Wave Double-Balanced Active Frequency Doubler in SiGe BiCMOS

This letter presents a high conversion gain double-balanced active frequency doubler operating from 36 to 80 GHz. The circuit was fabricated in a 200 GHz ${rm f}_{rm T}$ and ${rm f}_{max}$ 0.18 $mu$m SiGe BiCMOS process. The frequency doubler achieves a peak conversion gain of 10.2 dB at 66 GHz. The maximum output power is 1.7 dBm at 66 GHz and ${-}3.9$ dBm at 80 GHz. The maximum fundamental suppression of 36 dB is observed at 60 GHz and is better than 20 dB from 36 to 80 GHz. The frequency doubler draws 41.6 mA from a nominal 3.3 V supply. The chip area of the active frequency doubler is 640 $mu$m $,times,$424 $mu$m (0.272 mm $^{2}$) including the pads. To the best of authors' knowledge, this active frequency doubler has demonstrated the highest operating frequency with highest conversion gain and output power among all other silicon-based active frequency doublers reported to date.      

Design of a Beam Switching/Steering Butler Matrix for Phased Array System

A compact broadband 8-way Butler matrix integrated with tunable phase shifters is proposed to provide full beam switching/steering capability. The newly designed multilayer stripline Butler matrix exhibits an average insertion loss of 1.1 dB with amplitude variation less than $pm$2.2 dB and an average phase imbalance of less than 20.7$^{circ}$ from 1.6 GHz to 2.8 GHz. The circuit size is only $160times 100 {rm mm}^{2}$, which corresponds to an 85% size reduction compared with a comparable conventional microstrip 8-way Butler matrix. The stripline tunable phase shifter is designed based on the asymmetric reflection-type configuration, where a Chebyshev matching network is utilized to convert the port impedance from 50 $Omega$ to 25 $Omega$ so that a phase tuning range in excess of 120$^{circ}$ can be obtained from 1.6 GHz to 2.8 GHz. To demonstrate the beam switching/steering functionality, the proposed tunable Butler matrix is applied to a 1 $times$ 8 antenna array system. The measured radiation patterns show that the beam can be fully steered within a spatial range of 108 $^{circ}$.      

Operation of a 25-Gb/s Direct Modulation Ridge Waveguide MQW-DFB Laser up to 85 $^{circ}$ C

We demonstrated a 25-Gb/s direct modulation up to 85 $^{circ}$C with a 1.3- $mu$m InGaAlAs ridge-waveguide multiple-quantum-well distributed-feedback laser. The dependence of the relaxation oscillation frequency on current was 3.3 GHz/mA$^{1 / 2}$, and this is the highest value ever reported for 200-$mu$m-long lasers in the 1.3-$mu$m wavelength region. The $alpha$ parameter was around 2.7 at 25 $^{circ}$C, and an error-free operation after a 10-km single-mode fiber transmission was obtained up to 85 $^{circ}$C.      

A Relationship Between Phase Delay and Attenuation Due to Rain and Its Applications to Satellite and Deep-Space Tracking

We present and discuss two main results concerning the relationship between phase delay due to rain and rain attenuation, useful in calculations concerning high precision tracking of satellites and deep-space spacecrafts using interferometry techniques. We have found these two results with the Synthetic Storm Technique [SST] applied to a large data bank of rain rate time series collected at three sites in Italy. The first result concerns a formula that provides the extra signal phase delay $tau$ (picoseconds) due to rain as a function of rain attenuation $A$ (dB), frequency $f$ (GHz) and slant path elevation angle $theta$ (degrees), given by $tau = (860.4 - 4.82 theta)f^{- 1.71}A^{0.73}$, for $20^{circ} leq theta ≪ 44^{circ}$, and by $tau = 648.3f^{- 1.71}A^{0.73}$, for $44^{circ} leq theta leq 90^{circ}$ . The formula allows estimating the phase delay due to rain attenuation, with overall average (normalized) error ${-}3hbox{%}$, standard deviation 11.1%, root-mean square 11.5% for 20$^{circ}$ slant paths. The second result concerns a method to predict phase delay from the probability distribution of rain rate (SST probability model), very useful when only the probability distribution of rain rate is known.      

Operation of Pt/AlGaN/GaN-Heterojunction Field-Effect-Transistor Hydrogen Sensors With Low Detection Limit and High Sensitivity

To enhance the device sensitivity and detection limit, a gate bias is applied to the catalytic metal of AlGaN/GaN-heterojunction field-effect-transistor (HFET) hydrogen sensors to control the carrier concentration in the channel at operation. The sensors exhibit a good sensitivity at temperatures up to 800 $^{circ}hbox{C}$ and a detection limit of 10-ppb $ hbox{H}_{2}$ in $hbox{N}_{2}$. The dependence of the device sensitivity on gate and drain biases has been investigated. The sensitivity peaks at the gate bias of threshold voltage and the drain bias of knee voltage in sensing gas. At high temperatures and $hbox{H}_{2}$ concentrations, specifically from 300 $^{circ}hbox{C}$ and 1000-ppm $hbox{H}_{2}/hbox{N}_{2}$, respectively, the sensitivity of HFETs at $V_{rm gs} = -hbox{3.5} hbox{V}$ and $V_{rm ds} = hbox{1} hbox{V}$ is more than three orders higher than their sensitivity at $V_{rm gs} = hbox{0} hbox{V}$ and the sensitivity of Schottky diodes.      

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.      

VCSEL Module With Polymer Optical Output Rods to Enable High Efficiency Coupling for Optical Interconnection

New vertical-cavity surface-emitting laser (VCSEL) modules—designed with a optical output rod surrounded by cladding—have been proposed to realize high-efficiency low-cost optical interconnection. Prototypes have been fabricated using a photomask transfer method employing two kinds of ultraviolet curable resin. Observation of the near-field pattern and eye pattern for signal transmission shows that output rods with a diameter of 50- $mu$m efficiently confine the laser beam as an optical waveguide. In addition, ray tracing simulation indicates that this new VCSEL offers greater positional tolerance—as much as $+$18/ $-$22 $mu$m—for coupling to optical wiring in 90$^{circ}$ light path conversion.      

A New Transceiver Architecture for the 60-GHz Band

A new “half-RF” architecture incorporates a polyphase filter in the signal path to allow the use of a local oscillator frequency equal to half the input frequency. The receiver performs 90 $^{circ}$ phase shift and two downconversion steps to produce quadrature baseband outputs. The transmitter upconverts the quadrature baseband signals in two steps, applies the results to a polyphase filter, and sums its outputs. Each path employs a dedicated 30-GHz oscillator and is fabricated in 90-nm CMOS technology. The receiver achieves a noise figure of 5.7–7.1 dB and gain/phase mismatch of 1.1 dB/2.1$^{circ}$ while consuming 36 mW. The transmitter produces a maximum output level of $-$7.2 dBm and an image rejection of 20 dB while drawing 78 mW.