A frequency synthesizer device with amplitude control, the device comprising: an oscillator circuit having: an inductive-capacitive, LC, tank circuit having: a capacitive element, and an inductive element (L1,L2) that is connected to the capacitive element; driver circuits that are configured to reinforce oscillation to generate output signal that oscillates in response to voltage applied to the tank circuit and a transconductance gain provided to the oscillator circuit; a switch circuit ( φ 1, φ 2) that is configured to operate in a first mode in which the capacitive element of the oscillator circuit is held at a charge voltage that corresponds to a supply voltage and in a second mode in which the tank circuit oscillates, wherein the switch circuit includes a switch that prevents current from flowing through the inductive element in the first mode; and a plurality of auxiliary circuits that are each configured to adjust, in response to being enabled, an amplitude of the output signal by changing the transconductance gain provided to the oscillator circuit; and a calibration circuit configured to detect an amplitude of the output signal, and adjust, in response to the detected amplitude, how many of the plurality of auxiliary circuits are enabled. an oscillator circuit having: an inductive-capacitive, LC, tank circuit having: a capacitive element, and an inductive element (L1,L2) that is connected to the capacitive element; driver circuits that are configured to reinforce oscillation to generate output signal that oscillates in response to voltage applied to the tank circuit and a transconductance gain provided to the oscillator circuit; a switch circuit ( φ 1, φ 2) that is configured to operate in a first mode in which the capacitive element of the oscillator circuit is held at a charge voltage that corresponds to a supply voltage and in a second mode in which the tank circuit oscillates, wherein the switch circuit includes a switch that prevents current from flowing through the inductive element in the first mode; and a plurality of auxiliary circuits that are each configured to adjust, in response to being enabled, an amplitude of the output signal by changing the transconductance gain provided to the oscillator circuit; and an inductive-capacitive, LC, tank circuit having: a capacitive element, and an inductive element (L1,L2) that is connected to the capacitive element; a capacitive element, and an inductive element (L1,L2) that is connected to the capacitive element; driver circuits that are configured to reinforce oscillation to generate output signal that oscillates in response to voltage applied to the tank circuit and a transconductance gain provided to the oscillator circuit; a switch circuit ( φ 1, φ 2) that is configured to operate in a first mode in which the capacitive element of the oscillator circuit is held at a charge voltage that corresponds to a supply voltage and in a second mode in which the tank circuit oscillates, wherein the switch circuit includes a switch that prevents current from flowing through the inductive element in the first mode; and a plurality of auxiliary circuits that are each configured to adjust, in response to being enabled, an amplitude of the output signal by changing the transconductance gain provided to the oscillator circuit; and a calibration circuit configured to detect an amplitude of the output signal, and adjust, in response to the detected amplitude, how many of the plurality of auxiliary circuits are enabled.