Dan Kuylenstierna

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A method for design of low phase-noise balanced-Colpitts (BC) fixed-frequency oscillators (FFOs) and wideband voltage-controlled oscillators (VCOs) is presented. Analytical expressions describe how to design an oscillator for best phase noise, given a limited <i>Q</i> factor and a certain active device. The theory needs only two free parameters: the(More)
In this paper, a new discrete-time model of phase noise for digital communication systems, based on a continuous-time representation of time-varying phase noise is derived and its statistical characteristics are presented. The proposed phase noise model is shown to be more accurate than the classical Wiener model. Next, using the this model, non-data-aided(More)
This paper addresses the limitations and difficulties, in terms of DC-current density restrictions, and process limitations, associated with implementing impedance inverters with high characteristic impedance for monolithic microwave integrated circuit (MMIC) Doherty power amplifiers (DPAs). It is theoretically shown that impedance inverters with high(More)
This paper reports on a novel lumped balun topology, the second-order lattice balun, with broad-band performance. The design is based on synthetic transmission lines operating as impedance transformers. The characteristic impedance of the synthetic transmission lines may be chosen to obtain inherent impedance transformation. An analytical investigation(More)
This paper presents the design of lumped quadrature power splitters (LQPSs) based on unit cells of right-handed (RH) and left-handed (LH) synthetic transmission lines (TLs). The LQPSs include a lumped Wilkinson splitter, with phase-adjusting RH/LH TLs at the outputs. Two topologies, considered to be advantageous with regards to size and electric(More)
This paper investigates the effect of oscillator phase noise and channel variations due to fading on the performance of communication systems at frequency bands higher than 10GHz. Phase noise and channel models are reviewed and technologydependent bounds on the phase noise quality of radio oscillators are presented. Our study shows that, in general, both(More)
This paper reports on compact tunable true-time delay lines based on ferroelectric (Ba/sub 0.25/Sr/sub 0.75/TiO/sub 3/) varactors integrated on high-resistivity silicon. The delay lines are based on lumped elements, physically implemented as synthetic coplanar-strip lines. An approximate analytical design procedure, exactly valid for /spl omega//spl rarr/0,(More)
Broadband monolithic InGaP HBT frequency doublers for K-band application have been developed. The designs employ a Gm-boosted differential common-base configuration using either capacitive or transformer-based coupling between base and emitters. To the authors' best knowledge, these are the first frequency doublers utilizing the Gm-boosted configuration and(More)
In this paper, we further develop the concept of a wideband Doherty power-amplifier topology with reconfigurable efficiency. This is done by presenting new theory that - in contrast to previous work - makes it possible to analyze how the performance of the amplifier depends on the input network properties and the choice of gate bias voltages. The utility of(More)
This paper presents an X-band balanced Colpitts oscillator in GaN HEMT technology and a method to calculate its phase noise accurately. The method employs a low-frequency (LF) noise measurement and the oscillator waveforms from a harmonic-balance simulator. These data are post-calculated by Hajimiri's phase-noise model, in which the LF noise can be(More)