GHz Frequency Bandwidth Research Articles

100MHz to 2.5GHz RF Detector Based on SiGe HBT

A RF received signal strength indication (RSSI) circuit with 100MHz to 2.5GHz frequency bandwidth was designed based on Jazz 0.18 μm SiGe HBT process. The RSSI was composed of 4 cascaded limiting amplifier and full wave current rectifier. A novel DC offset compensation circuit was adopted to achieve stable operating point. The circuit was simulated with Cadence design kit. Results showed that the RSSI had a wide dynamic range from 45dBm to 0dBm, operated at a 3.3V single supply. The power consumption is 18.8mW.

Design and characterization of an integrated microwave generator for BIST applications

This paper presents a circuit architecture for a new integrated on chip test method for microwave circuits. The proposed built-in-self-test (BIST) cell targets a direct low-cost measurement technique of the gain and the 1 dB input compression point (CP1) of a K-band satellite receiver in the 18–22 GHz frequency bandwidth. A signal generator at the radiofrequency (RF) front end input of the device under test (DUT) has been integrated on the same chip. To inject this RF signal, a loopback technique has been used and the design has been accommodated for it. This paper focuses on the design of the most sensitive block of the BIST circuit, i.e. the RF signal generator. This circuit, fabricated in a SIGe:C BiCMOS process, consumes 10 mA. It presents a dynamic power range of 17 dB (−41; −24 dBm) and operates in a frequency range of 5.6 GHz (17.5; 23 GHz). This BIST circuit gives new perspectives in terms of test strategy, cost reduction, and measurement accuracy for microwave-integrated circuits and could be adapted for mm-wave circuits.

A COMPACT AND WIDEBAND CIRCULARLY POLARIZED RECTENNA WITH HIGH EFFICIENCY AT X-BAND

A new design for a compact and wideband circularly-polarized rectenna with high efficiency operating at X-band is proposed. A dual-slot coupled antenna excited by an H-shaped slot fed by a T-shaped microstrip is designed to yield wideband performance as a receiving array antenna. Rectifying circuit models for harmonic suppression circuit, impedance matching, DC-pass circuit, and DC return circuit at the input and output of the diode are built up and optimized to transfer the maximum power from the antenna to the load using an ADS circuit simulator. An RF-DC conversion efficiency of 71.9% is measured on the conditions of 300 Omega load, and 50.1 mW RF input power at 9.5 GHz operating frequency. For the proposed wideband rectenna, the efficiency of more than 50% is measured over a 1 GHz frequency bandwidth. The measured gain, axial ratio, and return loss of the circularly polarized antenna with a 4-element array are 11.2 dBi, 1.1 dB, and -16.4 dB, respectively. The reflection coefficient of the array antenna is measured at less than -10 dB over a wide frequency range of about 2 GHz. Using this antenna as transmitting (TX) and receiving (RX) radiators, the free-space power transfer capability of the rectenna is tested in free space to turn on an LED at 25 cm distance.

Design and Analysis of Two Six-port Correlators

This paper presents design and analysis of two different Ultra Wide band (UWB) six-port correlators for transmitter and receiver applications. The two designs analyzed and compared in terms of transmission parameters, relative bandwidth and occupied area. On one side, design of microwave components for multi- Giga Hertz bandwidth is a non-trivial challenge. Meeting such challenging performance specifications requires a high degree of Electronic Design Automation (EDA)-tool skills and theoretical understanding of the limits and possibilities offered by the used circuit implementation. On the other side, an appropriate design methodology must be established and systematically used along the entire project development. Two different designs of a six- port correlator for more than 3 GHz frequency bandwidth are presented. The systematic design approach applied in the case of the six-port correlator can be extrapolated for any microwave circuit using passive components with transmission lines.

GaN/AlGaN waveguide quantum cascade photodetectors at λ ≈ 1.55 μm with enhanced responsivity and ∼40 GHz frequency bandwidth

We report on ultrafast GaN/AlGaN waveguide quantum cascade detectors with a peak detection wavelength of 1.5 μm. Mesa devices with a size of 7 × 7 and 10 × 10 μm2 have been fabricated with radio-frequency impedance-matched access lines. A strong enhancement of the responsivity is reported by illuminating the waveguide facet, with respect to illumination of the top surface. The room temperature responsivity is estimated to be higher than 9.5 ± 2 and 7.8 ± 2 mA/W, while the −3dB frequency response is extracted to be 42 and 37.4 GHz for 7 × 7 and 10 × 10 μm2 devices, respectively.

Realization of compact broadband rat-race coupler

In this article, a method to miniaturize the broadband rat-race couplers using microstrip nonuniform transmission lines (MNTLs) is presented. The proposed coupler features a compact size on a single circuit layer structure without reactive components and via-holes. The design formulas are developed using ABCD matrix and even–odd mode analysis. The theoretical analysis has been verified by measurement of the manufactured broadband MNTL rat-race coupler with center frequency of 1.35 GHz and 89% fractional bandwidth. The isolation, magnitude, imbalance and phase imbalance are less than –20 dB, 0.5 dB, and 4 degrees, respectively, within 0.75–1.95 GHz frequency bandwidth.

지상 운용 회전형 SAR 시험용 시스템 연구

A C-band ground-based rotational SAR system is presented in this paper. The rotaional SAR system is a test-bed for future rotational SAR systems which can be deployed in space and on a tower. The test-bed system is designed for imaging the electromagnetic scattering from earth surfaces and buried targets. This paper also presents the examination results of the generated SAR images. This rotational SAR system is basically consisted of the network-analyzer based HPS(Hongik Polarimetric Scatterometer) and a horizontally rotating arm. Several SAR images were obtained using the rotational SAR system for various target areas. To verify this system, we simulated the SAR images for the rotational SAR using the FDTD algorithm and compared between the measured and simulated SAR images. The rotational SAR system is operated at the center frequency of 5 GHz and various frequency bandwidth within 0.5~2 GHz to change the resolution of SAR images.

Two PIFA-Related Miniaturized Dual-Band Antennas

There are two novel printed inverted-F antenna (PIFA) related dual-band antennas for 2.45 and 5.25 GHz wireless local area network (WLAN) applications introduced in this paper. One is designed by spiraling the tail of the PIFA and the other is by modifying the feed structure of the PIFA into a coupling configuration. An equivalent transmission line model is proposed to explain the dual-band operation of the spiraling PIFA. The measurement results show that the former antenna has a 10 dB return loss with bandwidth 140 MHz in the 2.45 GHz frequency band and bandwidth 756 MHz at 5.25 GHz, whereas the latter one has the bandwidth 240 MHz at 2.45 GHz and bandwidth 672 MHz at 5.25 GHz. In addition, omnidirectional radiation patterns are achieved at those operating frequency bands with average antenna gains near 0 dBi. The proposed antenna possesses the properties of good performance, compact size (about 50% of a typical PIFA), low profile, and low cost; hence, it is suitable for practical applications in a combo WLAN system

Sampling of free-space magnetic pulses

We report free-space detection of magnetic pulses via the Faraday effect with shot-noise limited detection. This allows a 10−8 T / √Hz magnetic field resolution. The orthogonal propagation of the optical probe beam and the THz waves demonstrate a 1.3 ps risetime with a 400 GHz frequency bandwidth. The temporal and frequency responses of several crystals are reported with a theoretical response function analysis presented. The dispersion of the magnetic pulse into the sensor crystal is illustrated with a theoretical simulation for comparison. We also contrast the properties of electro-optic sampling with this magneto-optic sampling technique.

Variable gain amplifier with traveling wave structure

AbstractThis article presents a technique based on distributed structure in order to make a variable gain amplifier. A method to achieve a large dynamic gain range over a large frequency bandwidth is shown. The steps of design are presented and highlight a simple methodology. A two‐stage GCA (gain‐controlled amplifier) over a 2–12–GHz frequency bandwidth is shown and theoretical investigations for more complicated one are presented. © 1994 John Wiley & Sons, Inc.