A scalable reflection type phase shifter with large phase variation

We describe a reflection type phase shifter which exhibits a large phase shift range. We characterized its response between 1.95 GHz and 2.15 GHz and achieved over 400/spl deg/ phase shift with less than 4dB insertion loss. The transition time from 0/spl deg/ to 180/spl deg/ is <20 nS. Our design is scalable to mm-wave operation because it uses no inductors.     

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.     

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.     

A Three-Port Network with Constant Phase Difference Properties (Correspondence)

The 90/spl deg/ hybrid and the 180/spl deg/ TEM magic tee can, at least theoretically, be made to work over bandwidths of 10 to 1, and more. The device described is not limited to 90/spl deg/ or 180/spl deg/. It provides a phase shift between its outputs that is not only constant with frequency, but also capable of being set at any value. In addition, the ratio of the powers delivered to the outputs may be set as desired.     

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.     

360/spl deg/ Varactor Linear Phase Modulator

Theory is presented which 1) derives the circuit impedance requirements to match the nonlinearity of the varactor reactance-versus-voltage curve to the tangent /spl theta/ curve to obtain 180/spl deg/ linear phase modulation from one diode; 2) gives the value and position of a resistor to make insertion loss invariant with phase; and 3) derives the circuit requirements for combining two 180/spl deg/ diode phase moduIators in an admittance adding network to obtain 360/spl deg/ phase modulation. Experiments are disclosed rising series tuning at 1 GHz providing 360/spl deg/ phase modulation within /spl plusmn/ 3.0 percent of linearity, and using shunt tuning at 5 GHz providing 360/spl deg/ phase modulation within /spl plusmn/ 3.3 percent of linearity. A discussion is given of the application of the modulators to the serrodyne function.     

Lumped-element isolator with lower symmetrical configuration of three windings

Ideal isolator conditions are derived using circuit analysis in a lumped-element isolator with three windings at angles of /spl theta/ and /spl phi/. The angle /spl theta/ can be arbitrary; however, /spl phi/ is restricted to lie on the bisector of cross-angle /spl theta/ or the supplementary angle of /spl theta/. We found that the isolator with /spl theta/=/spl phi/=60 [deg] behaves the same as the one with conventional structure with /spl theta/=/spl phi/=120 [deg]. However, the former has a 0/spl deg/ phase shift and the latter a 180/spl deg/ phase shift between the input and output. The theoretical prediction was experimentally confirmed with an 800-MHz-band isolator.     

On the feasibility of CMOS multiband phase shifters for multiple-antenna transmitters

We present the design of an integrated multiband phase shifter in RF CMOS technology for phased array transmitters. The phase shifter has an embedded classical distributed amplifier for loss compensation. The phase shifter achieves a more than 180/spl deg/ phase tuning range in a 2.4-GHz band and a measured more than 360/spl deg/ phase tuning range in both 3.5-GHz and 5.8-GHz bands. The return loss is less than -10dB at all conditions. The feasibility for transmitter applications is verified through measurements. The output power at a 1-dB compression point (P/sub 1 dB/) is as high as 0.4dBmat 2.4GHz. The relative phase deviation around P/sub 1 dB/ is less than 3/spl deg/. The design is implemented in 0.18-/spl mu/mRF CMOS technology, and the chip size is 1200/spl mu/m /spl times/ 2300 /spl mu/m including pads.     

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.     

Broad-Band 180/spl deg/ Phase Shift Section in X Band (short Papers)

The use of an interdigitated coupler and a pair of switching circuits composed of appropriate diodes and two-stub matching circuits is experimentally shown to produce a broad-band reflection-type 180/spl deg/ phase shift section operating at 8.50-10.50 GHz with /spl plusmn/ 2/spl deg/ error when fabricated using microwave integrated circuit techniques.     

High Power, p-i-n Diode Controlled, Microwave Transmission Phase Shifters

An iterative circuit, diode, transmission phase shifter is discussed, having a canonic form that consists, of a length of transmission line symmetrically loaded at its ends by small susceptances whose values are diode controllable. The spacing of the susceptances is chosen so that their reflections are nearly mutually canceling, (about a quarter wavelength if equal magnitude, opposite sign susceptances are used). A change of electrical length of the section of 23/spl deg/, in principle, is obtainable with a maximum input VSWR of 1.04. Eight section, experimental circuits yielded 180/spl deg/ total phase shift with less than one decibel of loss in the L and S bands and peak RF power capability to 15 kilowatts. Operation to 140 kilowatts peak power was achieved with reduced phase shift per section. The transmission phase shifter is believed to be well suited as a phase control element for beam steering of array antennas.     

Broadband 180/spl deg/ bit phase shifter using a /spl lambda//2 coupled line and parallel /spl lambda//8 stubs

In this paper, a broadband 180/spl deg/ bit phase shifter using a new switched-network was presented. The new network is composed of a /spl lambda//2 coupled line and parallel /spl lambda//8 open and short stubs, which are shunted at the edge points of a coupled line, respectively. According to a desired phase shift, it provides a controllable phase dispersive characteristic by the proper determination of Z/sub m/,Z/sub s/, and R values. The 180/spl deg/ bit phase shifter operated at 3 GHz was fabricated and experimented using design graphs which provide the required Z/sub m/,Z/sub s/ values, and I/O match and phase bandwidths. The experimental performances showed broadband characteristics.     

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 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 Programmable Surface Acoustic Wave Matched Filter for Phase-Coded Spread Spectrum Waveforms (Short Papers)

A programmable surface acoustic wave (SAW) matched filter for biphase-coded spread spectrum waveforms has been constructed using a temperature-stable ST-cut quartz tapped delay line (TDL) and silicon-on-sapphire integrated control circuits. Construction is hybrid with wire stitch bond interconnections between the acoustic and microelectronic portions of the device. The SAW TDL operates at 120-MHz center frequency with 100-ns spacing between adjacent taps for a 10-MHz chip rate. The output of each tap can be individually switched to a load with 0 or 180/spl deg/ phase shift by the silicon-on-sapphire integrated control circuits. The high-speed capability of silicon-on-sapphire integrated circuits allows programming (code changing) to be achieved with a serial data input at 10-MHz rates, while the low temperature coefficient of ST-cut quartz allows satisfactory operation over a wide temperature range (-25/spl deg/C to +85/spl deg/C).     

2.4 GHz direct-digital binary phase shift keying modulator using MEMS switch

A novel MEMS-based binary phase shift keying direct-digital modulator operating at a carrier frequency of 2.4 GHz is presented. The circuit is composed of a rat-race coupler and a single-pole double-throw MEMS switch controlled by a digital baseband signal. The coupler divides the input waveform into two signals that are 180/spl deg/ out of phase and the MEMS switch is used to select between these two signals. This circuit has been experimentally verified and results are reported.     

Analysis of the equal-delay topology for transformers and hybrid networks

A complete scattering matrix representation for the ideal equal-delay topology for transformers and hybrid networks is presented. It is shown that while the operation of the hybrid as a 180/spl deg/ power combiner, current balun, or voltage balun is essentially frequency independent, the operation as a 0/spl deg/ power combiner or splitter is not. Instead, the isolation between the 0/spl deg/ and 180/spl deg/ ports is finite and frequency dependent. Moreover, the reflection coefficient at the sum port is nonzero and frequency dependent. These characteristics lead to the conclusion that while the equal-delay 180/spl deg/ power splitter/combiner is fundamentally frequency independent, its 0/spl deg/ counterpart is limited to operation well below the fundamental quarter-wave frequency of the constituent transmission lines. Full three-port scattering parameter representations, which are compatible with the calibration and analysis approach given in the CISPR 16-1 specification, are given for the three fundamental transformer and balun types derivable from the equal-delay hybrid: 1 the Guanella voltage balun, 2 the Guanella current balun, and 3 the 180/spl deg/ power divider or terminated hybrid balun, as specified in the CISPR 16-1 specification.     

Ring-hybrid microwave voltage-variable attenuator using HFET transistors

In this paper, a voltage-variable microwave attenuator circuit is presented. The input signal first enters a rat-race power splitter where a 0/spl deg/ and a 180/spl deg/ pair of signals is generated. The 0/spl deg/ signal passes through a common-gate field-effect transistor (FET) that is fully turned on, with its gate voltage set to 0 V. The 180/spl deg/ signal enters another common-gate transistor biased in the triode region. By changing the gate voltage of the second FET, the amplitude of the 180/spl deg/ signal is varied. The in-phase and out-of-phase signals are summed at the output and variable attenuation is achieved. The concept was demonstrated experimentally from 3.0 to 3.4 GHz and a variable attenuation from 6 to 30 dB was achieved. The phase response is linear over the frequency band and exhibits a group delay of 0.71 ns. The input 1-dB compression point of the attenuator is 0 dBm and the second harmonic suppression is 18.5 dB at 0-dBm input power.     

Linear tunable phase shifter using a left-handed transmission line

We demonstrate a compact, linear, and low loss variation hybrid phase shifter using a left-handed (LH) transmission line. For frequencies from 4.3 to 5.6 GHz, this phase shifter gives a nearly linear phase variation with voltage, with a maximum deviation of /spl plusmn/7.5/spl deg/. Within this frequency range, the maximum insertion loss is 3.6 dB, and the minimum insertion loss is 1.8 dB over a continuously adjustable phase range of more than 125/spl deg/, while minimum return loss is only 10.2 dB. Furthermore, this phase shifter requires only one control line, and it consumes almost no power.     

Development of multiband phase shifters in 180-nm RF CMOS technology with active loss compensation

We present the design and development of a novel integrated multiband phase shifter that has an embedded distributed amplifier for loss compensation in 0.18-/spl mu/m RF CMOS technology. The phase shifter achieves a measured 180/spl deg/ phase tuning range in a 2.4-GHz band and a measured 360/spl deg/ phase tuning range in both 3.5- and 5.8-GHz bands. The gain in the 2.4-GHz band varies from 0.14 to 6.6 dB during phase tuning. The insertion loss varies from -3.7 dB to 5.4-dB gain and -4.5 dB to 2.1-dB gain in the 3.5- and 5.8-GHz bands, respectively. The gain variation can be calibrated by adaptively tuning the bias condition of the embedded amplifier to yield a flat gain during phase tuning. The return loss is less than -10 dB at all conditions. The chip size is 1200 /spl mu/m/spl times/2300 /spl mu/m including pads.