A converter comprising: an input coupled to a power source; a plurality of power switches (Q1, Q2, Q3, Q4) coupled to the input; a resonant tank coupled to the plurality of power switches; and a controller coupled to the power switches, wherein the controller is configured to generate a plurality of gate drive signals for the power switches, and wherein the gate drive signals are arranged such that a switching frequency of the plurality of gate drive signals is in a frequency band; wherein in response to an operating condition change such as an input voltage variation, an input current variation, a power level variation, an output voltage variation, an output current variation, an operating temperature variation, the controller is configured to vary the frequency of the plurality of gate drive signals from a first switching frequency to a second switching frequency, and wherein the first switching frequency and the second switching frequency are within the frequency band, wherein: the frequency band comprises an upper limit and a lower limit, characterized in that: the upper limit and the lower limit are adjacent to a resonant frequency of the resonant tank, wherein the frequency band is determined through a control loop, and wherein a reference of the control loop is so arranged that the resonant frequency is within the frequency band, and wherein the reference follows a variable reference function, and wherein the variable reference function includes variables selected from the group consisting of an input voltage, an input current, an output voltage, an output current, an operating temperature. an input coupled to a power source; a plurality of power switches (Q1, Q2, Q3, Q4) coupled to the input; a resonant tank coupled to the plurality of power switches; and a controller coupled to the power switches, wherein the controller is configured to generate a plurality of gate drive signals for the power switches, and wherein the gate drive signals are arranged such that a switching frequency of the plurality of gate drive signals is in a frequency band; wherein in response to an operating condition change such as an input voltage variation, an input current variation, a power level variation, an output voltage variation, an output current variation, an operating temperature variation, the controller is configured to vary the frequency of the plurality of gate drive signals from a first switching frequency to a second switching frequency, and wherein the first switching frequency and the second switching frequency are within the frequency band, wherein: the frequency band comprises an upper limit and a lower limit, characterized in that: the upper limit and the lower limit are adjacent to a resonant frequency of the resonant tank, wherein the frequency band is determined through a control loop, and wherein a reference of the control loop is so arranged that the resonant frequency is within the frequency band, and wherein the reference follows a variable reference function, and wherein the variable reference function includes variables selected from the group consisting of an input voltage, an input current, an output voltage, an output current, an operating temperature.