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In this paper, a broadband upconversion image-reject mixer integrating a quadrature signal generator is presented. The polyphase networks (PPNs ) are used to convert the single-ended local-oscillator input signal to quadrature signals. A pair of inductors is added to traditional PPN to enhance the return loss performance, while optimizing the image-reject ratio. A common-emitter tranconductance using the feedforward technique is applied to a quadrature active Gilbert mixer to obtain relative high linearity, and the optical solution for high-frequency applications is given and analyzed. An active differential to single totem-pole balun is applied as the output stage, which is well matched to load impedance and can provide medium output power. Measured results show excellent performance in the designed frequency from 400 MHz to 6 GHz. [ABSTRACT FROM PUBLISHER]

A ring resonator loaded with five open stubs is proposed for the design of dual‐band bandpass filters. To shrink the filter layout, a pair of loaded quarter‐wavelength stubs is utilised to produce the first passband. On the other hand, the introduced coupling between the quarter‐wavelength stubs and the ring resonator produced transmission zeros for enhancing the selectivity. Both bandwidth and central frequency ratio of the two passbands can be adjusted freely by the circuit parameters. Two coupling lines are added beside the resonator as feed‐lines to construct a filter with high selectivity and compact size. A filter at 1.57/2.45 GHz is designed, fabricated and measured for verification. [ABSTRACT FROM AUTHOR]

This paper presents a tri-stubs loaded multimode resonator (TSLMR) for designing dual-band bandpass filters. The TSLMR produces four spitting modes and the modal character is analyzed by using odd- and even-mode methods. A pair of even–odd modes is used to form the first passband, while another pair is used to produce the second passband. This resonator structure provides sufficient degrees of freedom to control the central frequencies and bandwidth of each passbands. Meanwhile, multi-transmission zeros are properly tuned for the rejections between the two passbands and in the upper stopband. A dual-band BPF operating at 1.57 and 3.5 GHz is designed and fabricated. Without a shorted structure and extra resonator, the measured filter shows good performance for both in band matching and outside rejections of the desired dual-passbands. [ABSTRACT FROM PUBLISHER]

ABSTRACT A compact microstrip lowpass filter (LPF) which consists of a meander line, a coupled line and two open stubs is proposed. The mechanism for reallocating filter transmission zeros and the design procedure are explained. The simulated and measured results demonstrate that this LPF provides compact size, low insertion loss, and wide stopband. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:367-371, 2015 [ABSTRACT FROM AUTHOR]

A novel ultra‐wideband (UWB) bandpass filter with sharp rejection and a narrow notched band is presented. This filter is designed using a multiple‐mode resonator (MMR) which consists of a ring resonator and a stepped‐impedance stub. The MMR has six resonance frequencies and three transmission zeros (TZs). All three TZs are close to the resonance frequencies, thus creating sharp roll‐off and narrow notched bands. Different passband bandwidths and notched bands can be obtained by tuning the stepped‐impedance admittance ratios. The simulated and measured results demonstrate that this simple bandpass filter has 97.3 and 30.6 dB/GHz attenuation slope at the lower and upper transition bands, respectively. The 3 dB notched band is from 5.6 to 5.8 GHz with 10.3 dB insertion loss at 5.7 GHz. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports on a design of inverse class-E amplifier with finite D.C. feed inductance. The finite D.C. feed inductance is resonated by the parallel capacitance at the fundamental frequency. The direct design equations required to determine the optimum operations are derived in detail. Comparing with the classic inverse class-E amplifier, numerical results show that improvements in minimizing size, cost, and complexity of the circuit can be obtained by the inverse class-E topology with finite D.C. feed inductance. Comparing with the sub-harmonic and parallel-circuit class-E amplifiers, the inverse class-E topology with finite D.C. feed offers advantages for MMIC realization. Theoretical analysis is validated by numerical simulation and measurement. Excellent agreement between theory and simulation results is achieved. Comparison between simulations and measurements of an experimental circuit validate the feasibility of the design. A measured output power of 40.01dBm, with a drain efficiency of 80.16% and power-added efficiency of 78.93% were obtained at 250MHz with a 22-dBm input power. [Copyright &y& Elsevier]

This paper presents a parallel-circuit Class-E amplifier that maintains it operating characteristics even when the output capacitance of the transistor is greater than the optimum shunt capacitance. The finite dc feed inductor in the parallel circuit topology is replaced by a transmission-line compensation circuit to eliminate the limitations on the operating frequency imposed by the output capacitance. Theoretical formulas for the circuit elements of the proposed network are derived in detail, and the analysis is validated by simulation and measurement. The measured maximum output power of 40.1 dBm, drain efficiency of 77.5%, and power-added efficiency of 70.8% were obtained at 2.8 GHz with a 29.4-dBm input power. These measurements show a similar or better level of efficiency and output power that is reported for other amplifiers at lower frequencies using the same transistor. [ABSTRACT FROM AUTHOR]

Presented is a modified parallel-circuit class-E amplifier that operates above the theoretical maximum frequency, recovering the class-E operating conditions. The finite inductor in the parallel circuit topology is replaced by a more suitable network composed of four transmission lines. The theory formula of the circuit elements of the proposed network is derived in detail, and an example is designed and measured to validate the analysis. The measured maximum output power of 40 dBm, drain efficiency of 77.5%, and power-added efficiency of 70.8% at 2.8 GHz were obtained, showing excellent efficiency compared to that obtained by other amplifiers using the same device. [ABSTRACT FROM AUTHOR]

By combining a Wilkinson and a Gysel power divider (PD), a two-way PD has been designed, which contains two load resistors and one resistor between two output ports. There is a trade-off between the bandwidth and heat-handling capability for this proposed PD. For demonstration, one example PD is given. It has both acceptable bandwidth (about 66%) and acceptable heat-handling capability. [ABSTRACT FROM AUTHOR]