Chih Ming Lin

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 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 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 COMPACT BALUN BASED ON MICROSTRIP EBG CELL AND INTERDIGITAL CAPACITOR

A novel compact balun (balanced-to-unbalanced) that consists of a low-pass network served by a microstrip electromagnetic bandgap (EBG) cell and a high-pass …-network formed with an interdigital capacitor is presented. This proposed approach can efiectively operate the compact balun without the use of ‚=4 microstrip lines to reduce the circuit area over 50% compared to the conventional Marchand balun. The core dimension of the compact balun is 0:74cm£0:7cm. The planar structure enables an e-cient circuit design in printed circuit boards (PCB) without using any bonding wires, defected ground structures (DGS), or surface mounted devices (SMD). A compact balun operating in the 3GHz band has been implemented in a FR-4 PCB. From the measured results, the return loss of the input port is better than 15dB over the band from 2.6 to 4GHz. The amplitude and phase imbalances are less than 1.4dB and 3 - with the 20% operational bandwidth ranging from 2.7 to 3.3GHz, respectively.

A 10–40 GHz Broadband Subharmonic Monolithic Mixer in 0.18

A 10-40 GHz broadband subharmonic monolithic passive mixer using the standard 0.18 mum CMOS process is demonstrated. The proposed mixer is composed of a two-stage Wilkinson power combiner, a short stub and a low-pass filter. Likewise, the mixer utilizes a pair of anti-parallel gate-drain-connected diodes to achieve subharmonic mixing mechanism. The two-stage Wilkinson power combiner is used to excite a radio frequency (RF) and local oscillation (LO) signals into diodes and to perform broadband operation. The low-pass filter supports an IF frequency range from dc to 2.5 GHz. This proposed configuration leads to a die size of less than 1.1 times 0.67 mm 2 . The measured results demonstrate a conversion loss of 15.6-17.6 dB, an LO-to-RF isolation better than 12 dB, a high 2LO-to-RF isolation of 51-59 dB over 10-40 GHz RF bandwidth, and a 1 dB compression power of 8 dBm.

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A novel configuration of doubly balanced mixer is presented for operating over the 26-38 GHz band. The monolithic microwave integrated circuit (MMIC) was implemented by GaAs 0.15 mum pHEMT technology with the compact size of 1times2.5 mm2. A 180deg hybrid circuit and two identical Marchand baluns were employed to achieve good port-to-port isolation. They also have wide band performance, make the mixer more compact, and simplify IF extraction. This mixer has a conversion loss of better than 6 dB, a dc-10 GHz IF bandwidth, and the LO-to-RF and LO-to-IF isolations are better than 20 dB and 29 dB, respectively.

m CMOS Technology

A novel and compact 16-44 GHz ultra-broadband doubly balanced monolithic ring mixer for Ku- to Ka-band applications implemented with a 0.15-mum pHEMT process is presented. The proposed mixer is composed of a C-band miniature spiral balun and a 180deg hybrid formed with an interdigital coupler, a low-pass pi-network, and a high-pass T-network. The 180deg hybrid eliminates the use of a cross-over structure for application in the balanced mixer, as well as provides an output port for the RF extraction of up-converter application. This proposed configuration leads to a die size of less than 0.8times0.8 mm2 . From the measured results, the mixer exhibits an 11-14 dB conversion loss, a 27-50 dB high LO-to-IF isolation over 16-44 GHz RF/LO bandwidth, and a 1-dB compression power of 14 dBm for both down- and up-converter applications.

A 26–38 GHz Monolithic Doubly Balanced Mixer

A compact Ka-band doubly balanced diode mixer with new phase relationships is demonstrated. In this design, a novel configuration was employed to have good performance while keeping compact size and simple intermediate frequency (IF) extraction. It is flexible not only in layout design, but also in the reduction of IF inductance. The chip dimension is as small as 0.851.35 mm, implemented by using a 0.15 m PHEMT technology. This mixer has a conversion loss between 9 to 12 dB, a dc-3.5 GHz IF bandwidth, and a good port-to-port isolation in Ka band.

A 16–44 GHz Compact Doubly Balanced Monolithic Ring Mixer

A novel 12-40 GHz ultra-broadband doubly balanced monolithic ring mixer with a small chip size covering the Ku- to Ka-band applications implemented by a 0.15-mum pseudo- morphic high electron-mobility transistor process is presented. The proposed mixer consists of two spiral transformer baluns and a band-reject filter. The use of the spiral baluns leads to the achievement of a chip size less than 0.8 times 0.8 mm2. The radio frequency (RF) spiral balun with a band-reject filter served by an L-C resonator is used to improve the bandwidth of the mixer and to provide an output port for the intermediate frequency (IF) extraction as well. The mixer exhibits a 6-12 dB conversion loss, high isolation over 12-40 GHz RF/local oscillation bandwidth, a DC-8 GHz IF bandwidth, and a 1-dB compression power of 14 dBm for both down- and up-converter applications.

A New Ka-Band Doubly BalancedMixer Based on Lange Couplers

A scheme for V-band band-pass filter (BPF) with narrowband performance and compact chip size is implemented using the 0.15 μm GaAs pHEMT process. Based on the even- and odd-mode analysis in V-band BPF, the feature of the third harmonic suppression can be concisely verified. The proposed structure provides excellent selectivity at both sides of the passband and facilitates the realization of third harmonic suppression of up to 20 dB. Good return loss and reasonable insertion loss over the desired passband are also shown.