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.

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

We report the characterization of quality (Q)-factor of RF metal-semiconductor-metal (MSM) planar interdigitated varactors fabricated by standard AlGaN/GaN HEMT process. The MSM varactors have wide tuning range and exhibit high quality-factor at both the maximum and minimum capacitance values. The fundamental limitation of the Q-factor in the medium capacitance range is also revealed. The elimination of ohmic contact resistance in the MSM varactor configuration pushed up the peak Q-factor to 92 at 0.5 GHz and 41 at 1.1 GHz. The operation of the MSM varactor is modeled by a physical equivalent circuit, with which the dependence of the Q-factor over the entire tuning voltage range can be explained.

Q-factor characterization of RF GaN-based metal-semiconductor-metal planar interdigitated varactor

Electronically scanned arrays are required for space based radars that are capable of tracking multiple robots, rovers, or other assets simultaneously and for beam-hopping communication systems between the various assets. ^Traditionally, these phased array antennas used GaAs Monolithic Microwave Integrated Circuit (MMIC) phase shifters, power amplifiers, and low noise amplifiers to amplify and steer the beam, but the development of RF MEMS switches over the past ten years has enabled system designers to consider replacing the GaAs MMIC phase shifters with RF Micro-Electro Mechanical System (MEMS) phase shifters. In this paper, the implication of replacing the relatively high loss GaAs MMICs with low loss MEMS phase shifters is investigated.

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RF MEMS phase shifters and their application in phase array antennas

Multiple antenna transmitter and receiver architectures that combine antenna selection with RF pre-processing have been shown to significantly outperform conventional antenna selection with the same number of RF chains Often, performance close to a full complexity architecture (with more RF chains) is also achieved This work studies the effect of hardware and signal processing non-idealities on such architectures We show that they are robust to quantization, phase, and calibration errors introduced by RF phase-shifters, and also to the channel estimation errors While insertion loss does lead to performance degradation, performance better than conventional antenna selection is observed for typical insertion loss values

Antenna selection with RF pre-processing: robustness to RF and selection non-idealities

In this paper, fully integrated RF MEMS phase shifters with low insertion loss, narrow frequency band, and constant phase shift are designed, fabricated, and characterized for mobile satellite broadcasting/communication systems. The fabricated phase shifters are comprised of CPW lines, short/open ended-stubs, and RF MEMS capacitive shunt switches. The constant phase shift can be obtained by optimizing the length of the open-ended stub and the short-ended stub. The fabricated 3-bit phase shifter has insertion loss of avg. -2.0 dB, return loss of min. -10 dB, and phase error of avg. 2.0/spl deg/, respectively. The utilized RF MEMS switches are operated at between 15 and 20 volts.

Integrated RF MEMS phase shifters with constant phase shift

The design, fabrication and performance of a novel multi-octave five-bit GaAs MMIC phase shifter is described. The topology was specifically selected to minimize process variations on performance. The topology of 22.5/spl deg/ and 11.25/spl deg/ phase shift bits is a sharing Lange coupler. Low peak phase error (PPE) (/spl les/5 degree for 180/spl deg/, 90/spl deg/, 45/spl deg/ phase shift bits, /spl les/2.5/spl deg/ for 22.5/spl deg/, 11.25/spl deg/ phase shift bits), low VSWR (/spl les/1.7), low insertion loss variations (/spl les/12.8/spl plusmn/0.7 dB) are exhibited over 5 to 20 GHz frequency range. The chip size of the MMIC phase shifter is 4.2 mm/spl times/2.98 mm/spl times/0.1 mm.

A novel multi-octave five-bit monolithic phase shifter

A variable-capacitance model for a GaAs MESFET three-terminal varactor applied to MMIC voltage-controlled runing frequency is presented. In this model, because the source is connected with the drain, the gate capacitance is only considered by analytical expressions, which are classified into three different regions for gate bias voltage: a before-pinch-off region, an after-pinch-off region, and a transition region. The model also includes the free-carrier movement in the active region, which is a very important contributor to the gate capacitance. The analytical results with the use of this model, compared with the experiment and other models, support the validity of the derived variable-capacitance model. © 1996 John Wiley & Sons, Inc.

A mesfet variable-capacitance model for realizing mmic voltage-controlled function

Design, fabrication and performance of a X-band 5-bit GaAs MMIC phase shifter are described. It exhibits low RMS phase error (<1.7 degrees), good VSWR (<1.3), low insertion loss (<8.3 dB) and low insertion loss variation (</spl plusmn/0.5 dB) for all thirty-two phase states over the entire operational bandwidth in the 9.2/spl sim/10.3 GHz frequency range.

A X-band five-bit MMIC phase shifter

The design, fabrication and performance of an L-band 4-bit GaAs MMIC phase shifter are described. It exhibits low RMS phase error (<1.8 degrees), good VSWR (<1.5), and low insertion loss variation (4.91/spl plusmn/0.35 dB) for all sixteen phase states over the entire operational bandwidth in the 1.0-1.2 GHz frequency range.

A compact L-band four-bit MMIC phase shifter

A physics based model for C-V characteristic of integrated planar Schottky varactor diode in the microwave band is presented. The model takes into account the influences of the distribute channel series resistance introduced by the planar structure, the distributed junction capacitance, the junction reverse saturation leakage and the sidewall capacitance on the C-V characteristic, and reveals the dependence of the C-V characteristic on operating frequency. The theory is in good agreement with the experimental results.

Lin Jinting

Papers

A novel multi-octave five-bit monolithic phase shifter

A mesfet variable-capacitance model for realizing mmic voltage-controlled function

A X-band five-bit MMIC phase shifter

A compact L-band four-bit MMIC phase shifter

Physics based model for C-V characteristic of integrated planar Schottky varactor diode in microwave band