A switched gain element has an input differential transistor pair and a gain control stage formed of a transistor quad. The four transistors of the transistor quad are connected through respective impedances to a supply voltage. The junction of the impedances and the transistors are connected through further respective transistors to output terminals. The further transistors are switched on by respective control voltages applied to switchable current sources. The same control voltages are applied to the transistor quad. Thus, when first predetermined voltages are applied a first voltage corresponding to the value of two of the impedances is output and when second predetermined voltages are applied a second voltage corresponding to the value of the remaining two impedances is output. The invention may also be applied to a mixer for switching the gain.