A Latching Ring-And-Post Ferrite Waveguide Circulator

This paper presents the performance and normalized design parameters for a latching ring-and-post ferrite circulator in waveguide. A C-band circulator has provided an insertion loss of 0.35 dB and a 20-dB isolation bandwidth of 17 percent. When the circulator was matched for higher maximum isolation (50 dB) but narrower bandwidth (10 percent) at room temperature, the 20-dB isolation bandwidth was 7.8 percent across the -40/spl deg/ to +75/spl deg/C temperature range. Low-loss operation was obtained at pulsed powers up to 7.5 kilowatts, and at least 20 dB of isolation was maintained up to 100 kilowatts. This performance, in conjunction with a switching speed of a fraction of a microsecond, permits the use of these circulators for transmitting-receiving functions in high-reliability RADARs.     

A Digital Latching Ferrite Strip Transmission Line Phase Shifter

This paper is concerned with the development of a new type of latching phase shifter which combines submicrosecond switching with a compact strip transmission line structure. Digital increments of nonreciprocal phase shift are obtained by "latching" or switching the magnetization of appropriate square loop garnet or ferrite materials from one remanent state to another. The following data have been obtained for a four-bit, C-band model utilizing yttrium iron garnet (4/spl pi/M/sub 8/ = 1600 G): Center Frequency---5.45 Gc/s Phase Deviation---/spl les//spl plusmn/3 percent over an 8 percent frequency band Insertion Loss--- <0.9 db VSWR--- <1.50 Switching Time--- <0.3/spl mu/s with a 130 V, 13 amp pulse Switching Energy--- <200 /spl mu/J for 180/spl deg/ bit Length--- <6 inches.     

A Temperature-Stable, Fail-Safe, Latching Ferrite TR Switch

Use of transmitting-receiving (TR) ferrite switches in place of gas-discharge devices improves the noise figure, life, and reliability of RADAR receivers. This paper describes a TR ferrite switch that employs 180/spl deg/ differential-phase-shift toroids to provide essentially constant isolation and insertion loss over a wide temperature range, independence of isolation with respect to RF power, and full receiver protection in case of driver failure. The ferrite switch is functionally a transfer device that is reciprocal in terms of transmission-coefficient amplitudes but nonreciprocal with respect to transmission phases. An experimental C-band 180/spl deg/ ferrite switch has provided isolation ranging from 38 to 45 dB and an insertion loss of 0.4 dB across a -40/spl deg/C to +75/spl deg/C range and a peak power-handling capacity of 130 kW measured at 0.001 duty. The switching energy, not including driver losses, is approximately 150 /spl mu/J. The preceding values of isolation and insertion loss compare with 36 and 0.8 to 1.1 dB, respectively, across the above temperature range, for the combination of fixed circulator, limiter, and one switchable circulator.     

A transmit/receive IF chip set for WCDMA mobiles in 0.35 /spl mu/m CMOS

An implementation of the IF section of WCDMA mobile transceivers with a set of two chips fabricated in an inexpensive 0.35-/spl mu/m two-poly three-metal CMOS process is presented. The transmit/receive chip set integrates quadrature modulators and demodulators, wide dynamic range automatic gain control (AGC) amplifiers, with linear-in-decibel gain control, and associated circuitry. This paper describes the problems encountered and the solutions envisaged to meet stringent specifications, with process and temperature variations, thus overcoming the limitations of CMOS devices, while operating at frequencies in the range of 100 MHz-1 GHz. Detailed measurement results corroborating successful application of the new techniques are reported. A receive AGC dynamic range of 73 dB with linearity error of less than /spl plusmn/2 dB and spread of less than 5 dB for a temperature range of -30/spl deg/C to +85/spl deg/C in the gain control characteristic has been measured. The modulator measurement shows a carrier suppression of 35 dB and sideband/third harmonic suppression of over 46 dB. The core die area of each chip is 1.5 mm/sup 2/.     

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.     

A New Type of Latching Switchable Ferrite Junction Circulator

This paper presents an approximate theory and initial performance data for a new type of latching, switchable, ferrite junction circulator that is well suited for applications requiring fast (fractions of or several microseconds), low-energy (tens of microjoules in the microwave region) switching. The novelty of the device is the use of oppositely magnetized ferrite cylinder-and-ring assemblies within the region of circulation. The approximate theory yields the radius for circulation, bandwidth, and input impedance as functions of material properties and frequency. Operation of latched circulators has been demonstrated on assemblies operating in the region of 7.3 and 5.4 GHz. Insertion losses from 0.25 to 0.4 dB, 20-dB isolation bandwidths from 2.4 to 8.3 percent, and switching energies from 15 to 30 /spl mu/J have been obtained.     

High Average Power S-Band Digital Phase Shifter

A 100-kW-peak Z-kW-average-power liquid-cooled ferrite digital phase shifter has been constructed using beryllia cooling of the ferrite toroid to meet single axis scanned array requirements. The phase-shift cross section external to the ferrite toroids is completely filled with the beryllia. Experiments indicate that the maximum temperature rise in the ferrite is no greater than 45/spl deg/ C. In tests using flux drive to 2 kW, the phase shifter exhibits a maximum phase drift of /spl plusmn/ 6/spl deg/ for 90/spl deg/ differential phase shift. The differential phase shift versus frequency varies less than /spl plusmn/ 0.5/spl deg/ for a 3-percent bandwidth.     

New Edge-Guided Mode Isolator Using Ferromagnetic Resonance Absorption

A new edge-guided (EG) mode isolator is described in which nonreciprocal attenuation is due to the ferromagnetic resonance absorption caused by a strong dc magnetic field applied locally at the short-circuited edge of a ferrite microstrip line. From modal analysis, including the magnetic losses of ferrite substrate and the transversal variation of the internal dc magnetic field, the dominant EG mode has been proved to propagate along not only the conventional ferrite stripline but also a stripline with one edge short circuited to the ground. Dispersion relations and RF electric field distribution have been calculated numerically, and the upper limit of isolator bandwidth has been discussed with several design parameters. Based on the results, a practical EG mode resonance isolator has been successfully developed, which has more than 25 dB isolation loss and less than 1.0 dB insertion loss over a 4.0-8.0-GHZ frequency band throughout the - 10/spl deg/C-+60/spl deg/C temperature range,     

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.     

Small Analog Stripline X-Band Ferrite Phase Shifter (Correspondence)

A small analog X-band stripline phase shifter using commercially available ferrites provides a figure of merit of 300/spl deg/ /dB, average coil drive power of 30 mW and element weight less than 4 oz. Experiments on an element using a new zinc-doped magnesium-manganese ferrite have given a figure of merit of 450/spl deg/ /dB.     

A high-speed low-voltage double-switch optical crossconnect using stress-induced bending micromirrors

A high-speed low-voltage double-switch electrostatically actuated optical crossconnect (OXC) is demonstrated using stress-induced bending micromirrors. A curved polysilicon seesaw structure substantially lowers the electrostatic operating voltage of the OXC and provides a double-switch option. Large mirror deflection angles of 13/spl deg/ (mirror elevation of 290 /spl mu/m high) and 5/spl deg/ (cantilever deflection of 90 /spl mu/m high), corresponding to low operating voltages of 25 and 18 V, could be obtained. A submillisecond switching time (<850 /spl mu/s), a low optical insertion loss (0.65 dB), and a small polarization-dependent loss (<0.08 dB) are achieved.     

Converting baluns into broad-band impedance-transforming 180/spl deg/ hybrids

A technique for converting baluns into 180/spl deg/ hybrids by adding an in-phase power splitter is presented in this paper. Incorporating the broad-band antiphase and in-phase power splitting characteristics of the balun and power splitter results in a 180/spl deg/ hybrid with broad-band characteristics. This technique also provides a means of achieving perfect matching and output isolation for three-port lossless baluns. Applying this technique to a Marchand balun will result in a broad-band impedance-transforming 180/spl deg/ hybrid. Simple design equations based on the scattering matrix are presented. These theoretical results are validated by an experimental 180/spl deg/ hybrid using a coupled line Marchand balun. It achieves amplitude balance of 0.5 dB and phase balance of less than 5/spl deg/ from 1.2 to 3.2 GHz.     

Design and modeling of 4-bit slow-wave MEMS phase shifters

A true-time-delay multibit microelectromechanical systems (MEMS) phase-shifter topology based on impedance-matched slow-wave coplanar-waveguide sections on a 500-/spl mu/m-thick quartz substrate is presented. A semilumped model for the unit cell is derived and its equivalent-circuit parameters are extracted from measurement and electromagnetic simulation data. This unit cell model can be cascaded to accurately predict N-section phase-shifter performance. Experimental data for a 4.6-mm-long 4-bit device shows a maximum phase error of 5.5/spl deg/ and S/sub 11/ less than -21 dB from 1 to 50 GHz with worst case S/sub 21/ less than -1.2 dB. In a second design, the slow-wave phase shifter was additionally loaded with MEMS capacitors to result in a phase shift of 257/spl deg//dB at 50 GHz, while keeping S/sub 11/ below -19 dB (with S/sub 21/<-1.9 dB). The beams are actuated using high-resistance SiCr bias lines with typical actuation voltage around 30-45 V.     

Linearization of LED Nonlinearity by Predistortions

Light-emitting diode (LED) nonlinear differential gain (DG) and differential phase (DP) were measured, since they are important performance factors in video signal transmission. Typical, experimentally measured temperature dependence of DG and DP is also presented. A linearizing method for minimizing LED DG and DP distortions, using predistortion, is proposed and experimentally examined. With this technique, and with precise adjustment of the predistortion circuits, the DG of a typical LED was improved from 12.5 percent to less than 1 percent, and the DP from 2.8/spl deg/ to 1/spl deg/.This corresponds to an improvement in second and third-order harmonic distortions of 19 dB and 21 dB, respectively. DG and DP were measured with respect to the 3.58-MHz color subcarrier frequency superimposed on the 15.75-kHz horizontal scanning sawtooth wave. The linearization stability with regard to temperature variation was lowered to be less than 1-percent DG and 1/spl deg/ DP in the temperature range from 15 to 45/spl deg/C.     

A Highly Desensitized, Wide-Band Monolithic Amplifier

An all-diffused monolithic feedback triple with a maximum bandwidth of 50 MHz, 40 dB of feedback, and gain adjustable from 34 dB to 52 dB is described. Harmonic distortion is less than 0.15 percent at 0.5 MHz and gain variation is less than /spl plsmn/0.25 dB from -55/spl deg/C to +125/spl deg/C. Detailed analysis of the amplifier performance is carried out and an accurate design technique based upon transistor models is developed. A distributed base model is introduced which results in prediction of open loop gain and phase to within 10 percent of measured values at all frequencies below 200 Mc/s.     

An E-plane ferrite loaded simple waveguide radiator

Experimental investigations were conducted to examine the effect of dielectric loading on a ferrite loaded waveguide radiator (notch antenna). The antenna was made by symmetrically tapering an X-band waveguide. A cylindrical ferrite post was disposed at the apex of the notch and it was biased with a dc magnetic field. The antenna was tested for several notch angles namely 140/spl deg/, 120/spl deg/, 90/spl deg/, 80/spl deg/, 60/spl deg/ while ferrite was loaded with several dielectric sleeves, such as wood, polymer, pyrex. The dielectric loading with high permittivity material is found to give better radiation and scanning characteristics. The radial thickness of the dielectric ring is observed to affect the radiation.     

Novel flip-chip bonding technology for W-band interconnections using alternate lead-free solder bumps

A novel lead-free flip-chip technology for mounting high-speed compound semiconductor ICs, which have a relatively severe limitation regarding high-heat treatment, is presented. Solder bump interconnections of 0.95Sn-0.05Au were successfully fabricated by reflowing multilayer metal film at as low a temperature as 220/spl deg/C. The bumps were designed to have a diameter of 36 /spl mu/m with a gap between the chip and the motherboard of 24 /spl mu/m. The electrical characteristics of flip-chip-mounted coplanar waveguide chips were measured. The deterioration in reflection loss in the flip chip mounting was less than 3 dB for frequencies up to W-band.     

A Ka-band InP MMIC 180/spl deg/ phase switch

A new type of Ka band (26 to 36 GHz) 180 degree phase switch (bi-phase modulator) monolithic microwave integrated circuit has been developed for the EC funded FARADAY radio astronomy project. This integral component forms part of a chip set for a very low noise switching radiometer operating at a temperature of approximately 15 K. To maximize the sensitivity of the radiometer lattice-matched indium phosphide HEMT technology has been used: all of the active components of the radiometer, with the exception of the detectors, have been manufactured on a single wafer process. Design principles are described, together with a comparison of modeled and measured results. The results show an average insertion loss of 3.5 dB, return loss of better than 10 dB and an average phase difference close to 170/spl deg//spl plusmn/10/spl deg/ the 26-36 GHz band.     

Experiments with small V-band waveguide reflector feeds

The radiation patterns of simple rectangular waveguide feeds have been measured at V band. A low-cost test arrangement, operating in the far field but without any absorbers, is shown to give better than 0.5 dB repeatability and more than 30 dB of dynamic range. The general rules of waveguide-feed design for reflector antennas are applicable, but the tendency of narrow feed patterns is somewhat emphasized compared to observations in earlier work at C or X band. For horizontal polarization, the difference is 5 dB at 90/spl deg/ between WR-28 and WR-90 hardware. This is partly caused by an increase in the relative guide material thickness at shorter wavelengths. No clear connection between pattern widths of the two linear polarizations was observed if the guide height was increased, the largest momentary deviation being 3 dB for a rectangular 7.1 by 7.1 millimeter feed. Changes in the guide width had a monotone effect up to 3 dB at 90/spl deg/ offset. Very small feed aperture sizes, around /spl lambda//4 or less, did not show respective widening of 1 dB patterns, although such expected effects were visible at lower amplitude levels.     

A New Band-Splitting Filter for Guided-Millimeter-Wave Transmission Systems

A new Michelson-interferometer (MI) hybrid having a miter angle is developed for use as a millimeter-wave band-splitting filter. The construction and operating principle of the filter are described. The design method and the experimental results are also presented. This filter has low branching loss, yet keeps very wide band characteristics. For the 4W-120-GHz-frequency-range filter with 35/spl deg/ miter angle, the branching loss is 0.68-1.56dB. This is about 40 percent lower than that of the conventional MI filter. The input VSWR is less than 1.29 and the guard bandwidth is less than 250 MHz. This filter can be used for the 40-120-GHz guided-millimeter-wave transmission systems.