A mixer circuit comprises an input stage arranged to convert an input voltage signal received at an input of the mixer circuit into at least one current signal, and a frequency conversion stage comprising at least one switching element arranged to convert a signal component of the at least one current signal from an input frequency to a output frequency. The input stage comprises at least one resistance connected between the input of the mixer circuit and the at least one switching element. The at least one switching element and the at least one resistance are arranged such that the at least one switching element comprises a ‘turn-on’ resistance that exhibits a resistivity that is a factor less than the at least one resistance connected thereto.