Arbitrary dual-band components using composite right/left-handed transmission lines

Arbitrary dual-band microstrip components using composite right/left-handed (CRLH) transmission lines (TLs) are presented. Theory, synthesis procedure, and implementation of the dual-band quarter-wave (/spl lambda//4) CRLH TL are presented. Arbitrary dual-band operation is achieved by the frequency offset and the phase slope of the CRLH TL. The frequency ratio of the two operating frequencies can be a noninteger. The dual-band /spl lambda//4 open/short-circuit stub, dual-band branch-line coupler (BLC), and dual-band rat-race coupler (RRC) are also demonstrated. The performances of these dual-band components are demonstrated by both simulated and measured results. Insertion loss is larger than 23 dB for the shunt /spl lambda//4 CRLH TL open-circuit stub and less than 0.25 dB for the shunt /spl lambda//4 CRLH TL short-circuit stub at each passband. The dual-band BLC exhibits S/sub 21/ and S/sub 31/ larger than -4.034 dB, return losses larger than 17 dB, isolations larger than 13 dB, phase differences 90/spl deg//spl plusmn/1.5/spl deg/, and gain imbalance less than 0.5 dB at each passband. The dual-band RRC exhibits S/sub 21/ and S/sub 31/ larger than -4.126 dB, return losses larger than 12 dB, isolations larger than 30 dB, phase difference 180/spl deg//spl plusmn/4/spl deg/, and gain imbalance less than 0.2 dB at each passband.     

Distributed MEMS analog phase shifter with enhanced tuning

The design, fabrication, and measurement of a tunable microwave phase shifter is described. The phase shifter combines two techniques: a distributed capacitance transmission line phase shifter, and a large tuning range radio frequency (RF) microelectromechanical system (MEMS) capacitor. The resulting device is a large bandwidth, continuously tunable, low-loss phase shifter, with state-of-the-art performance. Measurements indicate analog tuning of 170/spl deg/ phase shift per dB loss is possible at 40 GHz, with a 538/spl deg/ phase shift per centimeter. The structure is realized with high-Q MEMS varactors, capable of tuning C/sub max//C/sub min/= 3.4. To our knowledge, this presents the lowest loss analog millimeter wave phase shifter performance to date.     

Characteristics of the composite right/left-handed transmission lines

The composite right/left-handed (CRLH) transmission line (TL) is presented as a general TL possessing both left-handed (LH) and right-handed (RH) natures. The dispersion diagram of the two-dimensional (2-D) CRLH-TL is obtained analytically based on the Bloch-Floquet theory, and the unique phenomenon of infinite guided-wavelength propagation, with nonzero group velocity at a nonzero frequency, is explained. It is shown analytically that when the CRLH TL is "balanced", two eigenfrequencies at the /spl Gamma/ point (/spl beta/=0) of the Brillouin zone (BZ) degenerate at /spl omega//sub /spl Gamma// and a seamless transition from the LH to the RH modes without a bandgap can be achieved. In addition, these phenomena are demonstrated experimentally in the case of a CRLH microstrip line.     

Metamaterial-based electronically controlled transmission-line structure as a novel leaky-wave antenna with tunable radiation angle and beamwidth

A metamaterial-based electronically controlled transmission-line structure is presented and demonstrated as a novel leaky-wave (LW) antenna with tunable radiation angle and beamwidth functionalities. This structure is, in essence, a composite right/left-handed (CRLH) microstrip structure incorporating varactor diodes for fixed-frequency voltage-controlled operation. Angle scanning at a fixed frequency is achieved by modulating the capacitances of the structure by adjusting the (uniform) bias voltage applied to the varactors. Beamwidth tuning is obtained by making the structure nonuniform by application of a nonuniform bias voltage distribution of the varactors. A rigorous analysis based on an extension of the CRLH concept is proposed and the corresponding dispersion curves, obtained by equivalent-circuit formulas with LC parameters extracted from full-wave simulation, are shown. A 30-cell LW antenna structure, incorporating both series and shunt varactors for optimal impedance matching and maximal tuning range, is designed. This prototype exhibits continuous scanning capability from 50/spl deg/ to -49/spl deg/ by tuning the bias voltages from 0 to 21 V at 3.33 GHz. A maximum gain of 18 dBi at broadside is also achieved. In addition, it provides half-power beamwidth variation of up to 200% with comparison to the case of uniform biasing. The effect of intermodulation due to the nonlinearity of the varactors is shown to be negligible for antenna applications. The antenna is tested in a 10-Mb/s binary phase-shift keying transmission link and successful recovery of the baseband data is demonstrated.     

Metamaterial-based electronically controlled transmission-line structure as a novel leaky-wave antenna with tunable radiation angle and beamwidth

A metamaterial-based electronically controlled transmission-line structure is presented and demonstrated as a novel leaky-wave (LW) antenna with tunable radiation angle and beamwidth functionalities. This structure is in essence a composite right/left-handed (CRLH) microstrip structure incorporating varactor diodes for fixed-frequency voltage-controlled operation. Angle scanning at a fixed frequency is achieved by modulating the capacitances of the structure by adjusting the (uniform) bias voltage applied to the varactors. Beamwidth tuning is obtained by making the structure nonuniform by application of a nonuniform bias voltage distribution of the varactors. A rigorous analysis based on an extension of the CRLH concept is proposed and the corresponding dispersion curves, obtained by equivalent-circuit formulas with LC parameters extracted from full-wave simulation, are shown. A 30-cell LW antenna structure, incorporating both series and shunt varactors for optimal impedance matching and maximal tuning range, is designed. This prototype exhibits continuous scanning capability from 50/spl deg/ to -49/spl deg/ by tuning the bias voltages from 0 to 21 V at 3.33 GHz. A maximum gain of 18 dBi at broadside is also achieved. In addition, it provides half-power beamwidth variation of up to 200% with comparison to the case of uniform biasing. The effect of intermodulation due to the nonlinearity of the varactors is shown to be negligible for antenna applications. The antenna is tested in a 10-Mb/s binary phase-shift key transmission link and successful recovery of the baseband data is demonstrated.     

A 360/spl deg/ Reflection-Type Diode Phase Modulator (Correspondence)

A 360/spl deg/ phase modulator using two series-tuned varactors in a parallel connection is described. The design minimizes the change in total phase shfit with frequency and gives a small attenuation ripple. The modulator is centered at 2 GHz and gives a total phase shift at 360/spl deg/ at the center frequency, an attenuation ripple of 1.3 dB over a 10-percent bandwidth and a 7/spl deg/ decrease of phase shift at the band edges.     

Low phase noise IP VCO for multistandard communication using a 0.35-/spl mu/m BiCMOS SiGe technology

In this letter, we report that a commonly used 0.35-/spl mu/m, 60-GHz-F/sub MAX/ BiCMOS SiGe monolithic microwave integrated circuit (MMIC) technology is able to provide very low phase noise signal generation in the X-band frequency range. This statement has been demonstrated using a differential LC voltage-controlled oscillator (VCO) in which varactors are realized with metal-oxide semiconductor (MOS) transistors and inductors with a patterned ground shield technology. This VCO features an output power signal in the range of -5 dBm and exhibits a phase noise of -96 dBc/Hz at a frequency offset of 100kHz from carrier and -120 dBc/Hz at a frequency offset of 1 MHz. The VCO features a tuning range of 430 MHz or 4.3% of its operating frequency. Its power consumption is in the range of 70 mW (200 mW with buffers circuits) for a chip size of 800/spl times/1000 /spl mu/m/sup 2/ (including RF probe pads).     

一种 CRLH 传输线结构的电调移相器设计

基于左右手复合传输线（CRLHTL,Composite Right／Left-Handed Transmission Line）提出了一种加载变容管结构的电调移相器,该移相器由两个电调复合传输线单元级联构成,每个复合传输线单元含3个变容二极管用以实现其相位传播常数以及等效特性阻抗的大范围调配。为方便工程使用,整个移相器6个变容二极管采用单一偏置电压控制,仿真以及最终测试结果均显示,在其工作的S频段内实现了可调相移量大于180°,相对带宽大于10％且回波损耗优于10dB的良好性能。     

Arbitrarily dual-band components using simplified structures of conventional CRLH TLs

Microwave components with nonlinear phase responses are developed using a simplified composite right/left-handed (CRLH) transmission-line (TL) structure without the series capacitance or the shunt inductance. Using such a simplified CRLH structure, arbitrarily dual-band microstrip components have been realized in compact sizes such as a quarter-wavelength short-circuited stub and dual- band branch-line couplers. Simulation and measurement results are given to demonstrate the efficiency and good performance of the proposed components. For the quarter- wavelength short-circuited stub based on the simplified CRLH-TL structure without the series capacitance, it has been shown that the insertion loss is less than -0.1dB. For the arbitrarily dual-band branch-line coupler, experiment results exhibit that S/sub 21/ and S/sub 31/ are larger than -3.6dB, the isolations are smaller than -30dB, the return losses are smaller than -20dB, and the phase differences are within 90/spl deg//spl plusmn/1.8/spl deg/.     

2.4 GHz continuously variable ferroelectric phase shifters using all-pass networks

Continuously variable ferroelectric (BST on sapphire) phase shifters based on all-pass networks are presented. An all-pass network phase shifter consists of only lumped LC elements, and thus the total size of the phase shifter is kept to less than 2.2 mm /spl times/ 2.6 mm at 2.4 GHz. The tunability (C/sub max//C/sub min/) of a BST interdigital capacitor is over 2.9 with a bias voltage of 140 V. The phase shifter provides more than 121/spl deg/ phase shift with the maximum insertion loss of 1.8 dB and the worst case return loss of 12.5 dB from 2.4 GHz to 2.5 GHz. By cascading two identical phase shifters, more than 255/spl deg/ phase shift is obtained with the maximum insertion loss of 3.75 dB. The loss figure-of-merit of both the single- and double-section phase shifters is over 65/spl deg//dB from 2.4 GHz to 2.5 GHz.     

A digitally controlled oscillator in a 90 nm digital CMOS process for mobile phones

We propose and demonstrate the first RF digitally controlled oscillator (DCO) for cellular mobile phones. The DCO is part of a single-chip quad-band fully compliant GSM transceiver realized in a 90 nm digital CMOS process. Wide and precise linear frequency tuning is achieved through digital control of a large array of standard n-poly/n-well MOSCAP devices that operate in flat regions of their C- V curves. The varactors are partitioned into binary-weighted and unit-weighted banks that are sequentially activated during frequency locking and tracking. The finest varactor step size is 12 kHz at the 1.6-2.0 GHz high-band output. To attenuate the quantization noise to below the natural oscillator phase noise, the varactors undergo high-speed second-order /spl Sigma//spl Delta/ dithering. We analyze the effect of the /spl Sigma//spl Delta/ dithering on the phase noise and show that it can be made sufficiently small. The measured phase noise at 20 MHz offset in the GSM900 band is -165 dBc/Hz and shows no degradation due to the /spl Sigma//spl Delta/ dithering. The 3.6 GHz DCO core consumes 18.0 mA from a 1.4 V supply and has a very wide tuning range of 900 MHz to support the quad-band operation.     

Distributed phase shifter with pyrochlore bismuth zinc niobate thin films

A monolithic Ku-band phase shifter employing voltage tunable Bi/sub 1.5/Zn/sub 1.0/Nb/sub 1.5/O/sub 7/ (BZN) thin film parallel plate capacitors is reported. BZN films were deposited by radio frequency magnetron sputtering on single-crystal sapphire substrates. A nine-section distributed coplanar waveguide loaded-line phase-shifter structure was designed. A differential phase shift of 175/spl deg/ was achieved with a maximum insertion loss of 3.5 dB at 15 GHz, giving a figure of merit /spl sim/50/spl deg//dB. To the best of our knowledge, this is the first demonstration of a monolithic tunable microwave circuit using BZN thin films.     

Tapered distributed analogue tunable phase shifter with low insertion and return loss

Some improvements for distributed Schottky diode tunable phase shifters are carried out. First, near- and far-end sections are tapered to improve return loss. Then, to reduce device length, and the number of varactors, inductances are added in series with the varactors, leading to an improved C/sub max//C/sub min/ ratio. For a 360/spl deg/ tunable phase shifter working at 1 GHz, insertion losses are limited to 2.4 dB maximum. Return loss is better than 20 dB. The tapered sections allow a wide working frequency range, typically from 800 to 1200 MHz with the same characteristics: around 2.4 dB insertion losses, 20 dB return loss.     

Electronically scanned composite right/left handed microstrip leaky-wave antenna

A novel electronically scanned periodic microstrip leaky-wave (LW) antenna based on the concept of composite right/left-handed (CRLH) metamaterials is presented. This antenna includes varactors modulating the capacitive loading of the unit cell and therefore the propagation constant of the structure, which results in voltage scanning of the radiated beam. An accurate circuit model is proposed. The antenna is demonstrated experimentally to exhibit continuous scanning in the dominant mode from backward to forward angles. The scanning range is from -10/spl deg/ at 35 V to +7.5/spl deg/ at 0 V, and broadside occurs at 9 V, at the fixed frequency of 3.23 GHz.     

Millimeter-wave voltage-controlled oscillators in 0.13-/spl mu/m CMOS technology

This paper describes the design of CMOS millimeter-wave voltage controlled oscillators. Varactor, transistor, and inductor designs are optimized to reduce the parasitic capacitances. An investigation of tradeoff between quality factor and tuning range for MOS varactors at 24 GHz has shown that the polysilicon gate lengths between 0.18 and 0.24 /spl mu/m result both good quality factor (>12) and C/sub max//C/sub min/ ratio (/spl sim/3) in the 0.13-/spl mu/m CMOS process used for the study. The components were utilized to realize a VCO operating around 60 GHz with a tuning range of 5.8 GHz. A 99-GHz VCO with a tuning range of 2.5 GHz, phase noise of -102.7 dBc/Hz at 10-MHz offset and power consumption of 7-15mW from a 1.5-V supply and a 105-GHz VCO are also demonstrated. This is the CMOS circuit with the highest fundamental operating frequency. The lumped element approach can be used even for VCOs operating near 100-GHz and it results a smaller circuit area.     

Phase-Shift Characteristics of Helical Phase Shifters

The phase shifters considered consist of a helix surrounded by or surrounding a ferrite toroid. The ferrites work at their maximum remanent magnetization. It is shown that the helix surrounding a ferrite allows at any combination of frequency and helix diameter a larger differential phase shift than the helix surrounded by a ferrite does; and that in the latter helix the phase shift is easily disturbed by the TE/sub 11/ mode. It is furthermore shown that the 3/spl lambda//4 per turn helix offers a larger fractional bandwidth than the /spl lambda//4 per turn helix does unless one uses ferrites with very low saturation magnetization. The theoretical results are supplemented by experimental data.     

Design of wide-band CMOS VCO for multiband wireless LAN applications

In this paper, a general design methodology of low-voltage wide-band voltage-controlled oscillator (VCO) suitable for wireless LAN (WLAN) application is described. The applications of high-quality passives for the resonator are introduced: 1) a single-loop horseshoe inductor with Q > 20 between 2 and 5 GHz for good phase noise performance; and 2) accumulation MOS (AMOS) varactors with C/sub max//C/sub min/ ratio of 6 to provide wide-band tuning capability at low-voltage supply. The adverse effect of AMOS varactors due to high sensitivity is examined. Amendment using bandswitching topology is suggested, and a phase noise improvement of 7 dB is measured to prove the concept. The measured VCO operates on a 1-V supply with a wide tuning range of 58.7% between 3.0 and 5.6 GHz when tuned between /spl plusmn/0.7 V. The phase noise is -120 dBc/Hz at 3.0 GHz, and -114.5 dBc/Hz at 5.6 GHz, with the nominal power dissipation between 2 and 3 mW across the whole tuning range. The best phase noise at 1-MHz offset is -124 dBc/Hz at the frequency of 3 GHz, a supply voltage of 1.4 V, and power dissipation of 8.4 mW. When the supply is reduced to 0.83 V, the VCO dissipates less than 1 mW at 5.6 GHz. Using this design methodology, the feasibility of generating two local oscillator frequencies (2.4-GHz ISM and 5-GHz U-NII) for WLAN transceiver using a single VCO with only one monolithic inductor is demonstrated. The VCO is fabricated in a 0.13-/spl mu/m partially depleted silicon-on-insulator CMOS process.     

Analysis of the phase noise in saturated SOAs for DPSK applications

A theoretical model is used to analyze the impact of phase noise on the performance of semiconductor optical amplifiers (SOAs) in the saturation regime for differential phase-shift keying (DPSK) applications. It is found that the variance of the differential phase error scales as T/sup 2///spl tau//sub c//sup 2/ for /spl tau//sub c//spl Gt/T, where T is the bit period and /spl tau//sub c/ is the carrier lifetime of the SOA. This suggests that the adverse effect of saturation-induced phase noise can be significantly reduced by increasing the bit rate or the carrier lifetime.     

A phase shifter on a slot line loaded with varactors designed on the basis on nanodimensional films of barium-strontium titanate

A monolithic phase shifter is designed on the basis of a slot transmission line periodically loaded with ferroelectric varactors. The varactors are designed on the basis of nanodimensional films of Ba_0.8Sr_0.2TiO₃. It is found that, in the frequency band from 12.0 to 13.5 GHz, the figure of merit of the phase shifter is more than double that in the case when the thickness of the nanodimensional ferroelectric film used for the varactors is decreased from 36 to 18 nm.     

Miniature and tunable filters using MEMS capacitors

Microelectromechanical system (MEMS) bridge capacitors have been used to design miniature and tunable bandpass filters at 18-22 GHz. Using coplanar waveguide transmission lines on a quartz substrate (/spl epsiv//sub r/ = 3.8, tan/spl delta/ = 0.0002), a miniature three-pole filter was developed with 8.6% bandwidth based on high-Q MEMS bridge capacitors. The miniature filter is approximately 3.5 times smaller than the standard filter with a midband insertion loss of 2.9 dB at 21.1 GHz. The MEMS bridges in this design can also be used as varactors to tune the passband. Such a tunable filter was made on a glass substrate (/spl epsiv//sub r/ = 4.6, tan/spl delta/ = 0.006). Over a tuning range of 14% from 18.6 to 21.4 GHz, the miniature tunable filter has a fractional bandwidth of 7.5 /spl plusmn/ 0.2% and a midband insertion loss of 3.85-4.15 dB. The IIP/sub 3/ of the miniature-tunable filter is measured at 32 dBm for the difference frequency of 50 kHz. The IIP/sub 3/ increases to >50 dBm for difference frequencies greater than 150 kHz. Simple mechanical simulation with a maximum dc and ac (ramp) tuning voltages of 50 V indicates that the filter can tune at a conservative rate of 150-300 MHz//spl mu/s.