Risto Kaunisto

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This paper presents a wideband digital frequency synthesizer architecture targeted for spectrum sensing applications. The proposed frequency synthesizer architecture is based on digital period synthesis (DPS), which inherently can achieve a wide operational bandwidth, extremely high-frequency resolution, and an instantaneous settling time with low power and(More)
A Chireix outphasing system for 2.14 GHz including two saturated class-B pseudomorphic high electron-mobility transistor power amplifiers (PAs) and a Chireix power-combining circuit is reported in this paper. In an outphasing system, an arbitrary input signal is divided into two constant envelope branches. The phase-only modulated branches are then(More)
A Chireix outphasing transmitter for Band I wideband code-division multiple-access base stations was implemented using a nonisolating power combiner and two high-efficiency saturated class-B power amplifiers for 20-W single-carrier power levels. Novel adaptive background calibration algorithms were developed and demonstrated for the mismatch calibration and(More)
A direct on-chip transmission measurement of the resonance frequency of an individual singly clamped carbon nanofiber relay is reported. The experimental results are in good agreement with a small signal model and show the expected tuning of the resonance frequency with changing bias voltage.
This paper describes the realization of a Chireix power combining part of an outphasing system for 2.14 GHz consisting of two saturated class-B power amplifiers and a Chireix power combiner circuit. The Chireix power combining scheme can be used in Chireix outphasing architecture, which is currently together with EER and the Doherty amplifier one of the(More)
The RF-response of a three-terminal carbon nanotube resonator coupled to RF-transmission lines is studied by means of perturbation theory and direct numerical integration. We find three distinct oscillatory regimes, including one regime capable of exhibiting very large hysteresis loops in the frequency response. Considering a purely capacitive transduction,(More)
This paper presents a digital interpolation chain for non-integer variable-ratio sampling rate conversion, targeted to 4G mobile applications. Such a system is needed in all-digital transmitters, where the sampling rate of the digital input to the RF front-end must be an integer fraction of the carrier frequency. A highly configurable architecture is(More)