A DC-DC converter comprising: an inductor operably connected between a first node and an output node; a high side switch operably connected between a high side supply input node and the first node; a low side switch operably connected between a low side supply input node and the first node; switch control circuitry operable to control the turn on of said high side switch based on a comparison of at least a first signal (ISNS) indicative of the current flow in the inductor with a second signal (V ERROR) indicative of a difference between the voltage at the output node and a target voltage characterised in that the switch control circuitry is operable such that said low side switch may be turned off prior to the high side switch turning on; and the switch control circuitry comprises emulation circuitry (500, 800) for emulating the change in inductor current during a period when both the high side and low side switches are turned off; wherein the emulation circuitry comprises circuitry (500; 503) for generating a first ramp signal and means for applying the first ramp signal to at least one of the first signal (ISNS) and the second signal (V ERROR) when the low side switch is turned off; the DC-DC converter further comprising a slope compensation circuit for applying a slope compensation ramp signal to at least one of the first and second signals prior to comparison and wherein the first ramp signal is applied to the slope compensation ramp signal; wherein the first ramp signal has either a slope substantially equal to (V OUT + Φ)/L or substantially equal to (V OUT)/L where V OUT is the output voltage of the inductor, Φ is a voltage drop associated with a parallel current path when the low side switch is off, and L is the inductance of the inductor. an inductor operably connected between a first node and an output node; a high side switch operably connected between a high side supply input node and the first node; a low side switch operably connected between a low side supply input node and the first node; switch control circuitry operable to control the turn on of said high side switch based on a comparison of at least a first signal (ISNS) indicative of the current flow in the inductor with a second signal (V ERROR) indicative of a difference between the voltage at the output node and a target voltage characterised in that the switch control circuitry is operable such that said low side switch may be turned off prior to the high side switch turning on; and the switch control circuitry comprises emulation circuitry (500, 800) for emulating the change in inductor current during a period when both the high side and low side switches are turned off; wherein the emulation circuitry comprises circuitry (500; 503) for generating a first ramp signal and means for applying the first ramp signal to at least one of the first signal (ISNS) and the second signal (V ERROR) when the low side switch is turned off; the DC-DC converter further comprising a slope compensation circuit for applying a slope compensation ramp signal to at least one of the first and second signals prior to comparison and wherein the first ramp signal is applied to the slope compensation ramp signal; wherein the first ramp signal has either a slope substantially equal to (V OUT + Φ)/L or substantially equal to (V OUT)/L where V OUT is the output voltage of the inductor, Φ is a voltage drop associated with a parallel current path when the low side switch is off, and L is the inductance of the inductor.