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Harmonic generation based on frequency multipliers has proven to be the most successful and widely used solid-state technology for generating power at submillimeter wavelengths. Over the last several years, the development of new device technologies, implementation of innovative circuits, and application of advanced integrated-circuit processing techniques to frequency multiplier design have resulted in unprecedented levels of performance throughout the submillimeter-wave frequency band. This paper reviews the technological innovations, device options, circuit architectures, and fabrication technologies that have made harmonic generation such a successful approach to source development in the submillimeter spectrum.

This paper proposes an 8-bit LC tuned digitally-controlled oscillator (DCO) that exploits a new tunable active inductor (TAI) with a high $Q$-factor. This TAI achieves a maximum $Q$-factor value of 98 over a frequency range of 1770MHz. It tunes from 3.55nH to 15.2nH. The proposed TAI is used in the resonator of a wide tunable low-phase-noise DCO-LC oscillator. The tuning circuitry of the DCO with an additional resistance contributes to better effective capacitance characteristics as compared to the basic topology. Thanks to the capacitive degeneration network formed by a resistance connected in parallel with a capacity, the achieved frequency resolution is between 3kHz and 16kHz without any dithering. The proposed DCO with capacitive degeneration oscillates at a frequency that can be tuned from 1.22 to 3.52GHz with 65% tuning range. It consumes 5.2-mA current from a 1.0-V voltage supply, achieves a phase noise of $-$105.8dBc/Hz at 1-MHz offset and exhibits a figure of merit (FoM) of $-$178dBc/Hz. The proposed digitally-controlled oscillator was implemented in TSMC 90-nm CMOS MS/RF technology.

The electrical properties of yttrium doped bismuth zinc niobium oxide (BZN) pyrochlore ceramics are explored by means of temperature dependent electrical conductivity dielectric constant and capacitance spectra in the frequency range of 0–3 GHz. It is observed that the doped BZN exhibit a conductivity type conversion from intrinsic to extrinsic as the doping content increased from 0.04 to 0.06. The thermal energy bandgap of the intrinsic type is 3.45 eV. The pyrochlore is observed to exhibit a dielectric breakdown at 395 K. In addition, a negative capacitance (NC) spectrum with main resonance peak position of 23.2 MHz is detected. The NC effect is ascribed to the increased polarization and the availability of more free carriers in the device. When the NC signal amplitude is attenuated in the range of 0–20 dBm at 50 MHz and 150 MHz, wide tunability is monitored. Such characteristics of the Y-doped BZN are attractive for using them to cancel the positive parasitic capacitance of electronic circuits. The canceling of parasitic capacitance improves the high frequency performance of filter inductors and reduces the common mode noise of the resonance signal.

Harmonic generation based on frequency multipliers has proven to be the most successful and widely used solid-state technology for generating power at submillimeter wavelengths. Over the last several years, the development of new device technologies, implementation of innovative circuits, and application of advanced integrated-circuit processing techniques to frequency multiplier design have resulted in unprecedented levels of performance throughout the submillimeter-wave frequency band. This paper reviews the technological innovations, device options, circuit architectures, and fabrication technologies that have made harmonic generation such a successful approach to source development in the submillimeter spectrum.