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This paper proposes a two-pole two-path mixed coupling tunable filter with a constant bandwidth. A novel frequency dependent I/O structure is presented to generate up to five adjustable transmission zeros (TZs) without increasing the order of the filter. Thus, the selectivity and the out-of-band rejection are enhanced simultaneously in a very compact size. With the coupling characteristic deeply analyzed,...
A directional coupler using edge coupled lines is designed and fabricated on a two-layer PCB with isolation being achieved through electrical balance. Measured results show 4dB coupling and 34dB isolation at a frequency of 2.5GHz with 16% matching bandwidth (−10dB). Isolation varies between 31dB to 36dB in the 2.3GHz to 3GHz frequency range.
A novel miniaturized broadband circulator for reconfigurable mobile handsets has been successfully developed. The circulator operating in a weak magnetic field below ferromagnetic resonance is derived by analyzing the equivalent circuit. The operating theory of the circulator has been confirmed by using the perturbation theory. The usable isolation band could be expanded to 1.71GHz to 2.17GHz, which...
The reflected group delay method of designing filters is demonstrated for the first time on a four pole quasi-elliptic filter requiring cross coupling. A design procedure is proposed that involves creating optimization curves from a lumped element filter and involves using these curves to design a microstrip filter. To validate the proposed design procedure, a microstrip filter with a center frequency...
A new compact tunable microstrip diplexer based on varactor-tuned dual-mode stub-loaded resonators is investigated. By using the dual coupling paths, the two channel filters can then be designed independently. In addition, by properly varying the dc bias voltages applied to the varactors loaded onto the dual-mode resonators, the passband frequencies of the diplexer can be changed over a wide tuning...
The paper presents a novel Class-C type QVCO using a capacitive source coupling mechanism to enhance the startup robustness over process-temperature-voltage variations. Class-C type oscillator has superior phase noise performance with low power consumption at the cost of weak startup. In this design, complementary architecture and capacitive source degeneration coupling are employed to increase the...
This paper introduces a new physical interpretation of a frequency-dependent source/load (S/L) coupling to multi-mode filter designs, thereby successfully generating (N + 1) transmission zeros (TZs) greater than the number of resonant modes N. It is made clear by a transmission-line based analysis with the help of a parameter-extraction technique that the frequency-dependent S/L coupling essentially...
In order to enable Simultaneous Transmit and Receive (STAR), it is essential to provide high isolation between antenna elements. A novel technique is presented here in which tunable resonators are used in the near-field of an array of antennas to provide transmission zeros in the coupling between antennas. By using two sets of tunable resonators between each set of adjacent antennas, it is possible...
Tunable high-Q intrinsically-switchable quasi-absorptive bandstop filters are presented in the 4 GHz to 6 GHz and 6.3 GHz to 11.4 GHz frequency ranges. Their responses can be reconfigured between all pass and tunable bandstop filter responses by simply tuning the center frequency of their resonators, avoiding insertion loss and control voltages associated with the series switches required in conventional...
It is shown that reflection-type (RT) dispersive delay structure (DDS) units are inherently superior to transmission-type (TT) DDS units in terms of analog signal processing resolution, since they provide a higher group delay swing. However, RT-DDS units suffer from the drawback of requiring a circulator to separate the input and output signals. In order to solve this issue, the paper presents a TT-DDS...
In this paper, a V-band ultra-low power Low Noise Amplifier (LNA) with enhanced bandwidth (BW) is presented. A positively coupled cascode transformer (PCCT), formed using cascode inductors at the emitter of the cascode transistors, is used to couple the signal between the first and second stage. Using an optimum coupling factor of 0.23 for the PCCT, a bandwidth improvement of 15 % was seen during...
This paper proposes a tunable and high directivity coupler that is used a RF power monitor in ultra-high field magnetic resonance imaging (MRI) systems. High directivity of a coupler is a critical factor to assure the accurate output in the reflected power measurement. To obtain a tunable and high directivity coupler, a novel directivity tuner includes tunable capacitors and resistors in a passive...
The evolution of modern mobile terminals has been driven by two key factors, the user interface and broadband connectivity. However, while the peak performance near the base station may be state-of-the-art, real world performance (in-building, in suburbs and rural areas, in-car and on-person) has substantially fallen over the years. This has not only impacted achievable data rates and reduced battery...
This paper presents a magnetically coupled bandpass filter (BPF) approach for power distribution to multiple implanted devices. The BPF design approach accounts for the multiple loads and enables maximum power transfer into each individual receiver for given coupling coefficients between the coils. The proposed concept is demonstrated by showing power distribution to two identical receivers below...
This paper describes a synthesis method for parallel-coupled filters based on short-circuited stub-loaded resonators. Synthesis formulas were derived for homogeneous medium. Simulations are presented to validate the theory for three relative bandwidths 2, 4 and 8 %. For a proof-of-concept a third-order stripline bandpass filter was designed with a passband ripple of 0.01 dB and a relative bandwidth...
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