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A compact millimeter-wave passive retrodirective antenna (RDA) array with substrate integrated waveguide (SIW) phase shifters integrated is presented in this paper. The primary function of the passive RDA array is to enhance the monostatic radar cross section (RCS) of the metal plate. SIW phase shifters are utilized to realize the phase criterion of the passive RDA array instead of only changing the...
In radar system, the signal system of signal source and the mode of signal generation play an important role in radar performance. According to the specific request of through-wall imaging radar (TWIR) systems, this paper chooses the stepped frequency continuous waveform(SFCW) radar, and uses the technology of phase locked logic(PLL) frequency synthesis to synthetize the stepped frequency signal....
A low-power sub-harmonic receiver front-end covering an RF frequency range of 18–21GHz with a converted IF range of 50–1550 MHz is demonstrated. The transformer-based inductive coupled resonators at the input of low-noise amplifier provide a wideband signal transformation and impedance matching effectively. Also, several circuit techniques such as GM boosted and 3D-inductors are employed for the LNA...
A miniaturized Wilkinson power divider and a branch-line coupler using a newly proposed shunt-stub-based meander artificial transmission line (ATL) are presented in this paper for ISM band applications. Open-circuited stubs are evenly placed in the blank area of the meander line to form the proposed ATL, which can be accurately designed by synthesizing microstrip lines with various characteristic...
This paper presents a low power CMOS impulse radio (IR) ultra-wide-band (UWB) transmitter with wide pulse rate variability for medical imaging. The proposed circuit is based on all digital architecture which generates pulse during high to low transition of input data bits. The simulated results have shown that the circuit can generate Gaussian mono-cycle pulses having pulse width of 120ps and peak...
A 4-element ultra-wideband dual-polarized array is presented in this paper. Tapered slot antennas are chosen as the array elements. The array is arranged in a #-shaped form, which is capable of avoiding high-level grating lobe and obtained better than 35dB port-isolation in the desired working band. A prototype of the array is fabricated. Measured results show that the VSWR ⩽ 2.5 bandwidth ranges...
In this paper, the wideband and dual-band architectures for digital predistorters (DPD) are compared in terms of the DPD models used, hardware implementations, complexity and linearization performance. The advantages and disadvantages of each architecture are outlined and hardware measurements are performed using an amplifier prototype to illustrate the differences between the two approaches.
The existing target localization algorithms in bistatic multiple-input multiple-output (MIMO) radar are based on the far-field assumption. However, when the targets are located close to the transmit and receive arrays, these algorithms are no longer valid. Aiming at the problem of near-field target localization in bistatic MIMO radar, the paper presents a novel algorithm of parameter estimation based...
Radio frequency power amplifiers operate most efficiently in the compression region and become less efficient as signal peak-to-average power ratio increases. This is due to the amplifier spending more time operating below peak power and, thus operating below its maximum efficiency. However, the use of the envelope tracking technique can dramatically increase the efficiency of RF transmitters. In...
This paper presents the complete link budget analysis of a VLC system. By calculating the transmitter's emitted power, the channel path loss and the receiver's input referred noise, the system SNR and BER performance are derived. Furthermore, a VLC transceiver system is implemented with the analog front-end using discrete components while the baseband in FPGA, and the experimental results demonstrate...
A two-stage power amplifier (PA) using GaN HEMTs is presented with a high power added efficiency (PAE) and good linearity. This PA employs a structure of a class-C PA driving a class-AB PA to obtain a high PAE while maintaining the linearity. Source-pull and load-pull techniques were implemented to achieve optimum output impedance and inter-stage matching condition to compromise the PAE and the linearity...
This paper presents the design of a concurrent tri-band Doherty Power Amplifier (DPA) for 1.84 GHz, 2.14 GHz and 2.65 GHz frequency bands. The frequency response around each operating band is maximally flattened adopting a new design strategy. The DPA is based on hybrid technology using two 8 W GaN HEMT as active devices. The results show a peak of drain efficiency higher than 60 % in each operating...
This paper describes the design and implementation process of a wideband 8×8 Butler Matrix for beamforming networks in the AWS and PCS 1900 MHZ bands. In order to obtain a system able to operate in the frequency range of 1710 MHz to 2155 MHz, compact wideband branch-line hybrids, Schiffman phase shifters, parallel Schiffman phase shifters and no crossovers were used to implement the wideband 8×8 Butler...
In this work, an on-chip inductor was designed and fabricated for high efficiency miniaturized wireless power transfer. The on-chip power receiving inductor is based on above-CMOS integration (ACI) post processing technique. The fabricated 4.5×4.5 mm2 ACI inductor achieved a large inductance of 4.24 µH and peak quality factor of 23 at 13.56 MHz frequency. The measurement of a wireless power transmission...
In this paper, a novel architecture of a digital RF transmitter for the future massive MIMO system is proposed, which features flexible deployment, low cost, small volume and power efficiency. The comparison with a traditional architecture is also provided. To evaluate the feasibility of the proposed architecture, a prototype of one radio channel is implemented. The prototype consists of a BBU (Base...
In this paper, we report a two-way sequential power amplifier (SPA) using GaN HEMTs. The proposed fully analog SPA delivers Psat of approximately 40dBm over 2–3 GHz covering 40% fractional bandwidth. The design consists of a 3dB input coupler, a main amplifier, a peak amplifier, and a 10dB output coupler for power combining. After proper designing and optimizing these critical wideband couplers in...
This paper presents a new design of power divider for dual-band application, in which both short- and open-ended stubs are applied. Closed-form design equations for the proposed power divider are derived. It is observed that the proposed power divider can operate at a large frequency ratio (2.4–5). For verification, the measured, calculated and simulated performance of a dual-band power divider operating...
Two novel compact ultra-wideband (UWB) bandpass filter is developed by using two kinds of stub-loaded triple-mode resonator doublets. The proposed doublet consists of two parallel but oppositely arranged stub-loaded resonators. An UWB filter is designed by cascading three doublets, and eleven transmission poles are obtained in its passband. The high-orders filter has a passband covering 3.4–10.4 GHz,...
This paper proposes a compact bandpass filter with excellent out-of-band performance. Stepped-impedance resonators (SIRs) are used to achieve an extended rejection bandwidth. Loaded stubs are also introduced to suppress the harmonic responses. The SIRs and the loaded stubs take up little extra room, and thus the proposed filter has a compact size. In this paper, a bandpass filter centered at 2 GHz...
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