Jui Chieh Chiu

Wilkinson Power Divider Using Microstrip EBG Cells for the Suppression of Harmonics

This letter presents a planar power divider with an effective technique for nth harmonics suppression. The proposed technique served by a microstrip electromagnetic bandgap cell is used to suppress the nth harmonics and reduce the length of a quarter-wave line over 30% as compared to the conventional divider. The planar structure enables an easy circuit design in printed circuit boards. From the measured results, a 32.5 dB suppression for the third harmonic and a 12 dB suppression for the fifth harmonic is obtained while maintaining the characteristics of a conventional Wilkinson power divider. It is able to achieve less than 3.4 0.1 dB of the two equivalent insertion losses, less than 23dB of the return loss, and better than 25dB of isolation at 2.4GHz.

A Novel Planar Three-Way Power Divider

A novel planar three-way power divider is proposed. Based on the conventional planar microstrip coupled line technology, the proposed three-way power divider can modify a three-way Wilkinson power divider from a three-dimensional configuration into a two-dimensional one, meanwhile, to keep the length of the circuit to be lambda/4. The planar structure enables easy circuit design in printed circuit boards and monolithic microwave integrated circuits. The design concept and implementation are discussed. From the measured results, less than 4.8plusmn0.1dB of the three equivalent insertion losses, less than 19.5dB of the return loss, and better than 17.5dB of isolation at 2.4GHz can be achieved

A 12-36GHz PHEMT MMIC balanced frequency tripler

A novel configuration of balanced frequency InGaAs pseudomorphic high electron mobility transistor (PHEMT) monolithic microwave integrated circuit (MMIC) tripler is proposed. A resonant LC filter is used to eliminate the fundamental frequency and a phase delay line is employed to suppress the second harmonic. The separation of the independent phase shifters makes the tripler more compact and flexible. The conversion loss of the tripler operating from 12 to 36GHz is less than 9.4dB at 9-dBm input power. As compared to the third-harmonic frequency, the fundamental frequency is suppressed more than 21.4dB while for the second harmonic is more than 22.3dB at 36GHz

A PCB-compatible 3-dB coupler using microstrip-to-CPW via-hole transitions

A 3-dB coupler by implementing microstrip-to-coplanar waveguide (CPW) via-hole transitions is proposed. The proposed coupler, with the advantages of wider coupled line widths and spacing without using any bonding wires, can eliminate the uncertain factors of conventional Lange couplers caused by the printed circuit board (PCB) manufacturing processes. The proposed coupler can be easily fabricated on a single-layer PCB substrate instead of using multilayer substrates. Good agreements between the simulation and the measurement in the frequency range from 0.45 to 5 GHz can be achieved. The measured results at the center frequency of 2.4 GHz have the return loss better than -15dB; the insertion loss of coupled and direct ports is about 3/spl plusmn/ 0.2dB and the relative phase difference of 89/spl plusmn/0.3/spl deg/. The dimension of the coupler is 3.1cm /spl times/ 1.8cm.

A 23–37 GHz Miniature MMIC Subharmonic Mixer

A novel configuration of subharmonic mixer using an anti-parallel diode pair is presented for operating over the 23-37 GHz band. The monolithic microwave integrated circuit is implemented by GaAs 0.15 mum PHEMT technology with the compact size of 0.85 times 0.85 mm2. This mixer employs a directional coupler, LC low-pass filter, and a short stub for isolating three ports corresponding to radio frequency (RF), local oscillation (LO) input, and intermediate frequency (IF) output ports. The directional coupler also provides impedance transformation between the diode pair, RF, and LO ports. This makes the subharmonic mixer more compact and flexible. The best conversion loss of the subharmonic mixer is 9.4 dB, and the LO-to-RF and LO-to-IF isolations are better than 22 and 31 dB, respectively.

A Compact Ka-Band Planar Three-Way Power Divider

A Ka-band planar three-way power divider which uses the coupled line instead of the transmission line is proposed to reduce chip size. The proposed planar topology, different from the conventional Wilkinson power divider, is analyzed and can provide not only compact but also dc block characteristics, which are very suitable for monolithic microwave integrated circuit applications. The divider implemented by a pHEMT process shows an insertion loss less than 5.1 dB and an output isolation better than 17 dB. A return loss less than 18 dB and a phase difference of 4.2deg at 30 GHz can be achieved. Finally, good agreements between the simulation and experimental results are shown.

A 3-dB Quadrature Coupler Suitable for PCB Circuit Design

A quadrature 3-dB coupler, which combines the advantages of a coplanar waveguide and microstrip line structure suitable for single-layer substrate printed circuit board (PCB) circuit design is proposed. As compared to the conventional Lange coupler, the proposed coupler with the advantages of increasing the coupled linewidths and coupling spacing without using extra bonding wires can solve the drawbacks of Lange coupler. In addition, the proposed structure can easily be realized in a single-layer substrate by PCB manufacturing processes to eliminate the effects and uncertain factors from a multilayer substrate. Good agreements between the simulation and measurement in the frequency range from 0.45 to 5 GHz can be seen. With the operation bandwidth ranging from 1.8 to 2.8 GHz, the measured results of the return loss are better than 18.2 dB and insertion losses of coupled and direct ports are approximately 3plusmn0.1 dB; the relative phase difference is approximately 89.8deg. The dimension of the circuit is 2.7 cm times1.6 cm times0.08 cm

A 3-dB Quadrature Coupler Using Broadside-Coupled Coplanar Waveguides

A 3-dB quadrature coupler which combines the advantages of broadside-coupling and coplanar waveguide structure suitable for a single-layer printed circuit board (PCB) circuit design is proposed. Compared to the recently published broadside-coupled structures, the proposed coupler can easily be realized in a single-layer substrate by using PCB manufacturing processes to eliminate the effects of uncertain factors from a multi-layer substrate. With the operation bandwidth ranging from 2.1 to 2.7 GHz, the measured return loss and isolation are all better than 19dB, and the insertion losses and relative phase difference between the direct and coupled ports are at 3.2 plusmn 0.1 dB and 90 plusmn 0.6deg, respectively. The dimension of the coupler is 2.1 cm times 1.9 cm.

A Variable Conversion Gain Star Mixer for Ka-Band Applications

A variable conversion gain star mixer for Ka-band applications has been presented. This monolithic microwave integrated circuit was implemented on AlGaAs/InGaAs/GaAs pseudomorphic high-electron-mobility transistor process with a chip size of 1.7times1.7 mm2. The mixer is modified from conventional star mixer to apply dc bias. The conversion gain of the mixer, controlled by the voltage of the diodes, could be applied to meet gain compensation requirements in communication systems. From the measured results, the circuit can provide 11.9 dB conversion gain and 9.3 dB gain adjustment by controlling voltage from 0 to 0.7 V at 30 GHz.

A Ka-band Monolithic Doubly-Balanced Mixer

A 26-38 GHz monolithic doubly balanced mixer is presented. In this design, a novel configuration was employed to have wide band performance while keeping compact size and simple IF extraction. The MMIC was implemented with WIN 0.15 mum PHEMT process and the chip size is 1 times 2.5 mm2. This mixer has a conversion loss of better than 6 dB with good port-to-port isolation and a DC-10 GHz IF bandwidth