Ming-Guang Chen

A Microstrip Ultra-Wideband Bandpass Filter With Cascaded Broadband Bandpass and Bandstop Filters

This paper develops a novel ultra-wideband bandpass filter by cascading a broadband bandpass filter with another broadband bandstop filter. Properly selected impedances of transmission lines achieve broadband bandpass and bandstop filters and make independent designs possible. Detailed design and synthesis procedures are provided; moreover, agreement between measured and theoretically predicted results demonstrates feasibility of the proposed filter. Due to its simple structure, the ultra-wideband bandpass filter newly introduced in this paper is suitable for integration in the single-chipped circuit or implementation on printed circuit boards.

Synthesizing Microstrip Branch-Line Couplers With Predetermined Compact Size and Bandwidth

A new method for designing the microstrip branch- line couplers with predetermined compact size and bandwidth is proposed in this paper. With the proposed approach, the size of the quarter-wavelength transmission line in the branch-line coupler can be reduced greatly. In addition, the proposed couplers can be easily fabricated on the printed circuit board without any lumped element. A chart concludes the relationship between bandwidth and size reduction rate. It shows that open stubs with low impedance perform better than those with high impedance; moreover, the more open stubs with low impedance utilized, the broader the bandwidth will be. Furthermore, the measured frequency responses show good agreement with the theoretical results.

Miniaturization of Microstrip Branch-Line Coupler With Dual Transmission Lines

The dual transmission lines are proposed to replace conventional quarter-wavelength transmission lines for a compact microstrip branch-line coupler in this study. The developed coupler can be easily fabricated on the printed circuit board without lumped element; moreover, its size is greatly reduced compared to the conventional branch-line coupler. Furthermore, simulated and measured frequency responses match well to validate the proposed coupler with dual transmission lines.

Wide Stopband Parallel-Coupled Stacked SIRs Bandpass Filters With Open-Stub Lines

In this letter, spurious passband suppression in parallel-coupled stacked stepped-impedance-resonators (SIRs) bandpass filters (BPFs) by means of open-stub lines is proposed and implemented. These filters are composed of parallel-coupled stacked SIRs and open stubs. Moreover, the structure with tapped feeding is employed to create transmission zeros near both sides of the passband skirt. The proposed structure can improve the harmonic suppression so that a wide upper stopband with a satisfactory attenuation level would appear in this BPF. Measured results of the fabricated circuits show that the idea works very well

Design of Planar Complex Impedance Transformers With the Modified Coupled Line

Complex impedance transformers with the modified coupled line are provided in this paper. With the modified coupled line as proposed, the electrical length of the impedance transformer would be smaller than a quarter wavelength. In addition, analytic equations for the design of complex impedance transformers are derived; optimal characteristic impedance and impedance transformation are also calculated for successful power transfer. Simulation and measurement have demonstrated transformation efficiency and the potential for application of the proposed structure to radio frequency and microwave circuits.

Closed-loop power control of radio frequency power amplifier module with an on-chip embedded power detector

A quad-band GSM/GPRS power amplifier module is designed with a built-in ability of RF power transmitting control. Within the RF power transmitting control loop, a RF power detecting circuit with another reference circuit are embedded together onto the same InGaP/GaAs HBT power amplifier chip to achieve a good temperature compensation. Such power chips are then assembly with a silicon CMOS comparative chip by the multi-chip module technology and functions as a closed- loop power controlled GSM/GPRS power amplifier module. It had successfully demonstrated as play for all quad-band operations (GSM850, EGSM900, DCS1800, PCS1900).

Adopting the broadside coupled line for the design of an impedance transformer

A compact impedance transformer with the broadside coupled line is provided in this paper. With the assistant of the proposed broadside coupled line, the electrical length of the impedance transformer would be smaller than a quarter wavelength. In addition, analytic equations for the design of complex impedance transformer are derived; optimal characteristic impedance and transformation ratio for successful power transfer are calculated as well. Results of simulation and measurement demonstrate the efficient transformation and the potential for applications to radio frequency and microwave circuits.

Design of a microstrip dual-passband bandpass filter with modified quarter-wavelength stepped-impedance resonances

A novel microstrip dual-passband bandpass filter is proposed. With the assistance of modified quarter-wavelength stepped-impedance resonators, the dual-passband bandpass filter can be developed easily. Theoretical analysis and design procedures are provided; the prototypical bandpass filter with dual passbands is fabricated and measured as well. Well matched simulated results and experimental data validate the proposed filter.

A dual-band VCO module with harmonic suppression

The proposed dual-band VCO module with harmonic suppression has been disclosed in this paper. Designing this dual-band VCO module has involved both processes of LTCC and CMOS 0.18-mum for the dual-band filter and the dual-band VCO, respectively. Moreover, this design possesses the features of high integration and small size and realizes the implementation of the multichip module, which can be easily applied to the design of microwave or millimeter-wave integrated circuits.

A coplanar waveguide dual-band filter with spiral coupled lines

A new approach to realizing the miniaturized coplanar waveguide dual-band filter has been proposed. Embedding the spiral coupled line into the lowpass filter, the filter can readily generate dual passbands. The center frequencies of two passabands are designed at 2.4 and 5.8 GHz. The corresponding design equations have been described under ideal lossless conditions. Moreover, this coupler can be fabricated using a standard printed circuit board process, of which being easily applicable to the design of microwave or millimeter-wave integrated circuits.