The disclosure relates to an oscillator for use in generating frequencies in a frequency synthesizer, comprising: a first inductor element forming a metal trace loop with at least one turn, and a first capacitive circuit arranged to form a first resonance circuit with the first inductor element and being connected to the first inductor element through at least one first connection terminal, wherein the first capacitive circuit comprises at least one capacitive element and an electrical components arrangement arranged to establish and maintain an oscillation. The oscillator is characterized in that a second capacitive circuit comprising at least one capacitive element and an arrangement of electrical components, is arranged to form a second resonance circuit with the first inductor element and being connected to the first inductor element through at least one second connection terminal located on the opposite side of the first inductor element in respect to the first connection terminal of the first capacitive circuit, wherein the first and second resonance circuits are tuned to substantially the same frequency. The invention also relates to a frequency synthesizer and to a network node for use in a telecommunications network.