Common mode rejection circuit

An oscillation device comprising:

• an oscillator configured to provide a variable oscillation frequency;
• and
• a common mode rejection circuit element connected to the oscillator in series and comprising a resonant circuit configured to reject a common mode current through the oscillator, wherein a resonance frequency of the resonant circuit is adjustable, the common mode rejection circuit element including a plurality of switchable inductors configured to have an inductance value as a function of the variable oscillation frequency and an operational mode parameter, wherein the operational mode parameter is a selected power input,
• wherein the oscillator comprises a differential amplifier, one or more inductors and an adjustable capacitor for selecting the oscillation frequency, wherein the adjustable capacitor is connected in parallel with the one or more inductors,
• wherein the differential amplifier comprises two differential transistor pairs which are coupled as push-pull stages,
• wherein a type of the transistors of a first differential transistor pair differs from a type of the transistors of a second differential transistor pair,
• wherein each transistor of the two differential transistor pairs is coupled with the other transistor of the respective differential transistor pair via a mutual feedback loop, and
• wherein the adjustable capacitor and the one or more inductors are connected between a common drain contact of a first push-pull stage and a common drain contact of a second push-pull stage.

A method for operating an electrical circuit comprising a circuit element and a common mode rejection circuit element, the method comprising the following steps:

• operating the circuit element at a selected frequency within a variable frequency range;
• adjusting the common mode rejection circuit element based on the circuit element, wherein adjusting the common mode rejection circuit element comprises selectively switching one or more of a plurality of series-connected inductors of the common mode rejection circuit element to have an inductance value as a function of the selected frequency and an operational mode parameter, wherein the operational mode parameter is a selected power input;
• and
• rejecting a common mode current through the circuit element by use of the common mode rejection circuit element.