K-band HBT and HEMT monolithic active phase shifters using vector sum method

Two monolithic 3-bit active phase shifters using the vector sum method to K-band frequencies are reported in this paper. They are separately implemented using commercial 6-in GaAs HBT and high electron-mobility transistor (HEMT) monolithic-microwave integrated-circuit (MMIC) foundry processes. The MMIC HBT active phase shifter demonstrates an average gain of 8.87 dB and a maximum phase error of 11/spl deg/ at 18 GHz, while the HEMT phase shifter has 3.85-dB average measured gain with 11/spl deg/ maximum phase error at 20 GHz. The 20-GHz operation frequency of this HEMT MMIC is the highest among all the reported active phase shifters. The analysis for gain deviation and phase error of the active phase shifter using the vector sum method due to the individual variable gain amplifiers is also presented. The theoretical analysis can predict the measured minimum root-mean-square phase error 4.7/spl deg/ within 1/spl deg/ accuracy.     

Distributed 2- and 3-bit W-band MEMS phase shifters on glass substrates

This paper presents state-of-the-art RF microelectromechanical (MEMS) phase shifters at 75-110 GHz based on the distributed microelectromechanical transmission-line (DMTL) concept. A 3-bit DMTL phase shifter, fabricated on a glass substrate using MEMS switches and coplanar-waveguide lines, results in an average loss of 2.7 dB at 78 GHz (0.9 dB/bit). The measured figure-of-merit performance is 93/spl deg//dB-100/spl deg//dB (equivalent to 0.9 dB/bit) of loss at 75-110 GHz. The associated phase error is /spl plusmn/3/spl deg/ (rms phase error is 1.56/spl deg/) and the reflection loss is below -10 dB over all eight states. A 2-bit phase shifter is also demonstrated with comparable performance to the 3-bit design. It is seen that the phase shifter can be accurately modeled using a combination of full-wave electromagnetic and microwave circuit analysis, thereby making the design quite easy up to 110 GHz. These results represent the best phase-shifter performance to date using any technology at W-band frequencies. Careful analysis indicates that the 75-110-GHz figure-of-merit performance becomes 150/spl deg//dB-200/spl deg//dB, and the 3-bit average insertion loss improves to 1.8-2.1 dB if the phase shifter is fabricated on quartz substrates.     

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 miniature 15-20-GHz continuous-phase/amplitude control MMICs using 0.18-/spl mu/m CMOS technology

The design and performance of two new miniature 360/spl deg/ continuous-phase-control monolithic microwave integrated circuits (MMICs) using the vector sum method are presented. Both are implemented using commercial 0.18-/spl mu/m CMOS process. The first phase shifter demonstrates all continuous phase and an insertion loss of 8 dB with a 37-dB dynamic range from 15 to 20 GHz. The chip size is 0.95 mm /spl times/ 0.76 mm. The second phase shifter can achieve all continuous phase and an insertion loss of 16.2 dB with a 38.8-dB dynamic range at the same frequency range. The chip size is 0.71 mm /spl times/ 0.82 mm. To the best of the authors' knowledge, these circuits are the first demonstration of microwave CMOS phase shifters using the vector sum method with the smallest chip size for all MMIC phase shifters with 360/spl deg/ phase-control range above 5 GHz reported to date.     

A 2-bit miniature X-band MEMS phase shifter

The design and performance of a compact low-loss X-band true-time-delay (TTD) MEMS phase shifter fabricated on 8-mil GaAs substrate is described. A semi-lumped approach using microstrip transmission lines and metal-insulator-metal (MIM) capacitors is employed for the delay lines in order to both reduce circuit size as well as avoid the high insertion loss found in typical miniaturized designs. The 2-bit phase shifter achieved an average insertion loss of -0.70 dB at 9.45 GHz, and an associated phase accuracy of /spl plusmn/1.3/spl deg/. It occupies an area of only 5 mm/sup 2/, which is 44% the area of the smallest known X-band MEMS phase shifter . The phase shifter operates over 6-14 GHz with a return loss of better than -14 dB.     

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.     

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.     

Compact reflective microstrip phase shifter for traveling wave antenna applications

A varactor diode based microstrip phase shifter for 5.8GHz is presented. It is designed for use in microstrip traveling wave antennas where there is a strict limitation on the available space for the phase shifters. To meet all requirements, a reflective type phase shifter is chosen. Such a phase shifter includes a hybrid coupler. A compact branch line coupler is designed to make the phase shifter fit between the radiating elements in the antenna, while maintaining sufficient electrical performance. Phase shifters are designed with different types of stubs connecting the diodes to ground. A phase tuning range of 62/spl deg/ is measured for a phase shifter with parallel open stubs, and 92/spl deg/ with shorted stubs. Insertion loss is in both cases less than 0.6dB. A complete five-element array antenna is built and characterized. Measurements show beam scanning angles within /spl plusmn/32/spl deg/ from broadside.     

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.     

A High-Accuracy Microwave Phase Standard for Use in Primary Calibration Laboratories

This paper describes the theory and construction of a broad-band, differential phase shifter for use over the frequency range of from 4.25 to 6.20 GHz. Perturbations of the phase shifter which cause it to deviate from the ideal 2/spl theta/ operation are discussed. The analysis follows that of Fox, but is carried out in the exponential form, and includes both phase and attenuation constants. A set of nonideal conditions are postulated: improper positioning and matching of the constituent components, improper electrical Iengths of the differential phase shift sections, and loss in the dielectric slabs. Expressions are derived for each of the above conditions that demonstrate the effect on the 2/spl theta/ operation of the phase shifter. Evaluation of the experimental model shows that it operates within the predicted limits of error, /spl plusmn/ 0.5/spl deg/.     

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.     

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.     

Phase shifter with high phase shifts using defected ground structures

A novel phase shifter with defected ground structures (DGSs) for higher phase shift range is presented. The varactor diodes are mounted on DGSs of termination loads to control the large phase variation of the DGS at resonance. The experimental results of the proposed phase shifter show a 60/spl deg/ increase in maximum phase shift compared with that of a conventional one.     

Continuous Varactor-Diode Phase Shifter with Optimized Frequency Response

A method is introduced for designing continuous varactor-diode phase shifters with optimum frequency response. The circuit used gives very small frequency variations of the phase shift if the maximum phase shift of the device is less than about 200/spl deg/. Measurement results on a 180/spl deg/ L-band phase shifter are presented. This unit gives less than 5/spl deg/ variation of any given phase shift less than 180/spl deg/, when the frequency is changed from 1.5 to 1.7 GHz.     

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.     

Piezoelectric transducer controlled multiple beam phased array using microstrip Rotman lens

A simple and low-cost multiple beam phased array is designed using a microstrip Rotman lens and multi-line phase shifter controlled by a piezoelectric transducer (PET) at Ka-band. A microstrip Rotman lens with five beam ports and nine array ports is used as a feed for a multiple beam antenna array to generate five beams centered at the angles of 0/spl deg/, /spl plusmn/15/spl deg/, and /spl plusmn/30/spl deg/. The lens fed nine-element patch array shows the antenna gain of 10 dBi and sidelobe suppression of 10 dB. Each beam is steered over /spl plusmn/8/spl deg/ using two PET-controlled phase shifters, and the five beams cover /spl plusmn/38/spl deg/ from the broadside.     

RF MEMS phase shifters based on PCB MEMS technology

An X-band main-line type loaded line RF MEMS phase shifter fabricated using printed circuit based MEMS technology is reported. The phase shifter provides a phase shift of 31.6/spl deg/ with a minimum insertion loss of 0.56 dB at 9 GHz for an applied DC bias voltage of 40 V. These phase shifters are suitable for monolithic integration with low-cost phased arrays on Teflon or Polyimide such as low dielectric constant substrates.     

A tunable all-pass MMIC active phase shifter

This paper describes a novel structure for a monolithic-microwave integrated-circuit active phase shifter based on a bridge all-pass network. The design procedure has been developed, leading to a fixed-frequency circuit with large tunable phase variation, associated to a low-gain ripple, and requiring nearly no design optimization. Simulated results predicted an analog tunable 180/spl deg/ phase variation, at 5-GHz operation frequency. The circuit was implemented using GEC-Marconi pseudomorphic high electron-mobility transistor H40 technology, and measured results validated the proposed design method and circuit structure.     

Design and performance of a new digital phase shifter at X-band

A new digital phase shifter design at X-band is presented. The phase shifter operates based on converting a microstrip line to a rectangular waveguide and thus achieving the phase shift by changing the wave propagation constant through the medium. As a proof of principle, a 3-b phase shifter has been designed and constructed using PIN diode switches. An average insertion loss of 1.95 dB and phase shift error of less than 4/spl deg/ at 10.6 GHz are achieved.     

A new wide-band planar balun on a single-layer PCB

A new wide-band microstrip balun implemented on a single-layer printed circuit board (PCB) is presented in this letter. The proposed planar balun consists of a wide-band Wilkinson power divider and a noncoupled-line broad-band 180/spl deg/ phase shifter. To demonstrate the design methodology, one prototype is realized. The new design was simulated and validated by the measurement. Measured results show that 10-dB return loss of the unbalanced port has been achieved across the bandwidth from 1.7 GHz to 3.3 GHz, or 64%. Within the operation band, the measured return losses for both the two balanced ports are better than -10 dB, and the balanced ports isolation is below -1.5 dB. The measured amplitude and phase imbalance between the two balanced ports are within 0.3 dB and /spl plusmn/5/spl deg/, respectively, over the operating frequency band.