Masaomi Tsuru

A Triple-Tuned Ultra-Wideband VCO

We have already proposed a triple-tuned voltage-controlled oscillator (VCO) for achieving an ultra-wideband characteristic. The triple-tuned VCO consists of an active device and three tuned circuits. The fabricated VCO has achieved the oscillation bandwidth of 5.6-16.8 GHz and the phase noise of -114.9 dBc/Hz +/-2.9 dB at 1-MHz offset from the carrier. In this paper, for the first time, the conditions that the VCO achieves the ultra-wideband characteristic are clarified by formulation and simulation. It is also clarified that a transistor of the larger emitter size is suitable for the wideband VCO. In addition, the performances of the proposed VCO are compared with other reported wideband VCOs. As a result, it is shown that the proposed VCO has achieved the lowest figure of merit in the C-Ku-band.

Wideband VCO with triple tuned circuits in C-Ku band

This paper describes a wide-band voltage controlled oscillator (VCO) with the triple oscillation bandwidth and a better flatness of the phase noise in the oscillation bandwidth using triple varactor-tuned circuits. Altering capacitances of varactor diodes connected to every ports of a HBT in the same direction, the oscillation bandwidth of more than 1.5 octaves has been obtained. A fabricated VCO employing the triple-tuned circuits and a GaAs HBT has covered 1.56 octaves bandwidth achieving the phase noise of -114.9 dBc/Hz /spl plusmn/2.9 dB at 1 MHz offset from the carrier and the output power of 3.4dBm /spl plusmn/2 dB in C-Ku band.

A Planar Image Rejection Mixer with 135/45 deg Power Dividers

A planar image rejection mixer (IRM) with power dividers which have phase differences is presented. The 135 and 45 deg of the phase differences give high image rejection ratio and high LO-RF port isolation. Since this IRM consists of only planar circuits without the crossover between LO and RF lines, it is suitable for discrete configuration. The fabricated IRM with 135/45 deg power dividers has achieved -20 dB of image rejection ratio and 30 dB of LO-RF port isolation over the frequency range from 1.85 GHz to 2.9 GHz.

A Triple Tuned Ultra-Wideband VCO in X-K Band

We have already proposed a triple tuned voltage controlled oscillator (VCO) for achieving an ultra-wideband characteristic. The fabricated VCO in C-Ku band has achieved the oscillation bandwidth of 5.6 GHz-16.8 GHz. In this paper, for achieving the wide oscillation bandwidth in the higher frequency band we proposes a VCO that consists of a MMIC working as an active circuit and external hyper-abrupt junction varacter diodes connect to the MMIC with Au wires. The fabricated VCO in X-K band achieves the oscillation bandwidh of 9.9 GHz-21.9 GHz and the phase noise of - 109.4 dBc/Hz +/-2.4 dB at 1 MHz offset from the carrier. In addition, it is shown that the fabricated VCO achieves the widest oscillation bandwidth and the lowest phase noise in X-K band compared with other reported wideband VCOs.