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In this paper, a new design method for bridged-T coil (BTC) is proposed such that it can be made equivalent to two different transmission line sections at two different frequencies. In this way, on-chip dual-band branch-line coupler and dual-band power divider designs with very compact circuit sizes can be made possible through the use of BTCs. Specifically, the proposed 2.45/5.8-GHz dual-band branch-line coupler realized using the integrated passive device (IPD) process features a compact circuit size of only 2.8~\text mm \times 1.4 mm while the proposed 2.4/5.5-GHz dual-band power divider in IPD exhibits a very small circuit size of only 1.8~\text mm \times 1.7 mm. To the best of our knowledge, the proposed dual-band branch-line coupler is the smallest one ever reported while the circuit size of the proposed dual-band power divider is comparable to the smallest in the literature. [ABSTRACT FROM PUBLISHER]

In this paper, a GaAs absorptive single-pole double-throw (SPDT) RF switch and its application to a 2.4-GHz switched beamformer module are presented. The proposed absorptive SPDT RF switch features low-power consumption and low insertion loss with good output matching both in the on and off states. Specifically, the measured insertion loss in the on state is less than 1 dB, and the measured input and output return losses are both better than 11.2 dB from 1.9 to 2.6 GHz. The measured output return loss in the off state is better than 15 dB, and the measured isolation is better than 24.7 dB in the same frequency range. Two proposed absorptive SPDT switches are then employed to form an absorptive single-pole four-throw RF switch, and it is integrated with a miniaturized $4 \times 4$ Butler matrix using the integrated passive device (IPD) technology to achieve a compact 2.4-GHz switched beamformer module with a very low profile. Specifically, the module size is 4.9 mm $\times5$ mm with a thickness of only 0.4 mm. The IPD beamformer module is then used to realize a low-profile 2-D scanning antenna array, and 16 different beams in azimuth and elevation dimensions are successfully generated. [ABSTRACT FROM PUBLISHER]

In this paper, a miniature switched beamformer module for 2.4-GHz applications is proposed. The proposed beamformer module is based on the integrated passive device technology, and it integrates a 4 \times 4 Butler matrix, a single-pole four-throw beam-selection switch, and a p-i-n diode-based transmit/receive (T/R) switch into a compact module size of only 4.9 \text {mm} \times 5~\text {mm} \times 0.9 mm. To achieve the compact module size, bridged-T coils are used to replace the transmission line sections in the 4 \times 4$ Butler matrix and the T/R switch. The measured insertion loss at the center frequency of 2.4 GHz is within 10.89 ± 1.13 dB for the receive path and 11.33 ± 0.69 dB for the transmit path. The measured phase error is less than 8.4° at 2.4 GHz. The proposed beamformer features low cost, compact size, and low profile. It can help enable the use of phased array technique in handheld mobile devices. [ABSTRACT FROM AUTHOR]