Abstract:
A coplanar waveguide based microwave monolithic integrated circuit (MMIC) oscillator chip (14) has an active oscillator element (16) and a resonant capacitor (18) formed thereon and is flip-chip mounted on a dielectric substrate (12). A resonant inductor (22) is formed on the substrate (12) and interconnected with the resonant capacitor (18) to form a high Q-factor resonant circuit for the oscillator (10). The resonant inductor (22) includes a shorted coplanar waveguide section (24) consisting of first and second ground strips (24b, 24c), and a conductor strip (24a) extending between the first and second ground strips (24b, 24c) in parallel relation thereto and being separated therefrom by first and second spaces (26a, 26b), respectively. A shorting strip (24d) electrically interconnects adjacent ends of the conductor strip (24a) and first and second ground strips (24b, 24c), respectively. A dielectric film (34) may be formed over at least adjacent portions of the conductor strip (24a) and first and second ground strips (24b, 24c). The resonant inductor (22) is adjusted to provide a predetermined resonant frequency for the oscillator (10) by using a laser to remove part of the dielectric film (34) in the first and second spaces (26a, 26b) for fine adjustment, and/or to remove part of the shorting strip (24d) at the ends of the first and second spaces (26a, 26b) for coarse adjustment.
Abstract:
Die Erfindung bezieht sich auf einen modulierbaren Transistoroszillator großer Leistung für den Bereich sehr hoher Frequenzen. Bei diesem soll die modulierte Radiofrequenz in einem einstufigen Leistungsoszillator erzeugt wer - den bei einer möglichst verzerrungsfreien Erzeugung des erforderlichen Frequenzhubs bei hohem Leistungspegel des RF-Oszillators und möglichst geringem thermischen Geräusch. Die Erfindung sieht hierzu vor, daß das verstärkte Basisbandsignal über zwei Wege gleichphasig dem Oszillator zugeführt wird derart, daß einerseits über einen Vorspannungstransistor (Tr 2) die Basisvorspannung des RF-Transistors (TR 1) moduliert und andererseits über eine Modulationsdiode (22) die Frequenz des mit dem RF-Transistor (Tr 1) verbundenen Resonators (1) geändert wird. Ein erfindungsgemäßer Transistoroszillator ist insbesondere für den Einsatz in direkt modulierten Richtfunksystemen geeignet (Fig. 1).
Abstract:
A solution related to the control of common mode voltages within a frequency modulator and a magnetic resonance tomography system with the frequency modulator (1) is disclosed. The present invention relates to the frequency modulator (1) comprising: a first pair of diodes including two or more capacity diodes (6, 7); a second pair of diodes including additional two capacity didoes (16, 17); a first modulator input unit (2) for receiving a first modulation signal; and a second modulator input unit (18) for receiving a symmetrical second modulation signal (UM2). A pair of the diodes is combined with an oscillator unit (10).
Abstract:
A voltage controlled oscillator comprises a resonator for generating an oscillation signal, a frequency of which is in response to a control voltage; a transistor for amplifying the oscillation signal; oscillation frequency adjusting element for adjusting the frequency of the oscillation signal; and voltage control sensitivity adjusting element for adjusting a voltage control sensitivity of the oscillation signal.