Abstract-In this paper, a novel design method for a dual-band bandpass filter (BPF) with arbitrary controllable bandwidths based on a simple frequency mapping function is proposed and its analytical design equations are also derived. The circuit conversion techniques are employed for implementation with distributed transmission line. To validate the proposed dual-band BPF with controllable bandwidths, a low temperature co-fired ceramic (LTCC) transmission line as well as microstrip lines are used, respectively. The two types of design for the dual-band BPF have the same and significantly different fractional bandwidths (FBWs), respectively. The first type of dualband BPF with same FBWs are implemented at 2.11-2.17 and 3.45-3.55 GHz. The second type of dual-band BPF with different FBWs are implemented at 3.40-3.60 and 5.15-5.25 GHz. The measured and theoretical results show good agreement, significantly validating the proposed frequency mapping function methodology.

This article presents a compact dual-band (DB) branch line coupler (BLC) with different power division ratio at arbitrary two frequency bands. In this article, we add a technique to satisfy transmission lines of conventional BLC with different impedance at two bands, while they are transformed to p-type equivalent circuits. The design equations for DB BLC with different coupling coefficients at two bands are given. Furthermore, folded shape of shunt lines make about 77% circuit dimension comparing to conventional single-band BLC. A DB BLC operating different power division ratio at 0.9 and 2.0 GHz is demonstrated in excellent agreement with both circuit simulation and experimental results.ABSTRACT: The design of a V-band 54-GHz push-push voltagecontrolled oscillator (VCO) with a wide tuning range is presented in this article. The circuit is fabricated using 0.18-lm CMOS technology. A new single-turn inductor structure with a smaller inductance, which can reduce the substrate loss, is adopted for the oscillator core to have the performances of low phase noise and a wide tuning range. Besides, a new technique that delivers the output signal from the common drain of the two-stage buffers has been proposed to enhance the output power. The VCO core dissipates 8.54 mW from a 2 V supply. The buffer stage consumes 10.11 mW for raising the measured output power level up to À25 dBm. The measured output phase noise at an offset of 1 MHz from the carrier frequency of 53.0 GHz is about À94.45 dBc/Hz. This VCO, with a tuning range of 2.68 GHz (4.9%), shows the tuning-related figure-of-merit FOM T of À170.12 dB.

This paper proposes a new branch-line hybrid coupler with controllable power ratio at the output ports. It is structured as two 900 branch-line hybrid couplers connected by a variable impedance transmission line. The power division ratio is adjusted by controlling the impedance of the transmission line. Modeling the transmission line as series and parallel resonators shows that its impedance can be changed by changing the inductance and capacitance. In practice, using a varactor diode facilitates ease in dealing with the impedance of the transmission line and thus the power division ratio of the coupler.

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In this paper, a novel balun which can be applied for a microstrip-to-slotline transition is presented. This proposed balun has a DGS (Defected Ground Structure) pattern on the groundplane. This Balun has an advantage that does not require any addional electrical length. The proposed microstrip-to-slotline transition can be made to have power division and 180 degree out-of-phase characteristics. The DGS pattern on the groundplane decides the operatingfrequency of the proposed balun. In addition, the balun with a VPDGS (Vertically Periodic Defected Ground Structure) pattern on the ground plane is presented, designed, fabricated and measured.