A radio frequency receiver device (2, 2') comprising: a receiver input arranged to receive signals having one or more frequency components within a frequency spectrum; a filter (8, 8a, 8b, 8c) having a filter output impedance and arranged to filter said received signals; and an amplifier (10, 10a, 10b, 10c, 510, 1010, 1110) comprising: an amplifier input (34, 134a, 134b) connected to the filter output; an amplifier output (36, 72a, 72b); at least one radio frequency input transistor (44, 144a, 144b); a resistor-inductor-capacitor resonance load arrangement including a resistor (58, 158a, 158b), an inductor (56, 156a, 156b) and a capacitor (54, 154) and a feedback circuit including at least one feedback resistor (46, 146a, 146b), said feedback circuit being connected between the amplifier input (34, 134a, 134b) and the amplifier output (36, 72a, 72b); wherein the device (2, 2') is arranged to be selectably operable in: a first mode wherein the amplifier (10, 10a, 10b, 10c, 510, 1010, 1110) has first feedback resistance and transconductance values respectively such that the amplifier input impedance and the filter output impedance are substantially the same; and a second mode wherein the amplifier (10, 10a, 10b, 10c, 510, 1010, 1110) has second feedback resistance and transconductance values respectively such that upon connection of a predetermined external impedance matching circuit between the filter (8, 8a, 8b, 8c) and the amplifier (10, 10a, 10b, 10c, 510, 1010, 1110), the amplifier input impedance and the filter output impedance are substantially the same; wherein the second feedback resistance is selected such that a noise figure associated with the device (2, 2') when it is operated in the first mode is substantially equal to the noise figure when it is operated in the second mode with the predetermined external impedance matching circuit connected; wherein the second feedback resistance satisfies the following equation R FR2 = (g m1 R s -1)R L, wherein R FR2 is the second feedback resistance value, g m1 is the first transconductance value, R s is a source resistance value of the input transistor (44, 144a, 144b) and R L is the value of the resistor (58, 158a, 158b) of the resonance load arrangement. a receiver input arranged to receive signals having one or more frequency components within a frequency spectrum; a filter (8, 8a, 8b, 8c) having a filter output impedance and arranged to filter said received signals; and an amplifier (10, 10a, 10b, 10c, 510, 1010, 1110) comprising: an amplifier input (34, 134a, 134b) connected to the filter output; an amplifier output (36, 72a, 72b); at least one radio frequency input transistor (44, 144a, 144b); a resistor-inductor-capacitor resonance load arrangement including a resistor (58, 158a, 158b), an inductor (56, 156a, 156b) and a capacitor (54, 154) and a feedback circuit including at least one feedback resistor (46, 146a, 146b), said feedback circuit being connected between the amplifier input (34, 134a, 134b) and the amplifier output (36, 72a, 72b); an amplifier input (34, 134a, 134b) connected to the filter output; an amplifier output (36, 72a, 72b); at least one radio frequency input transistor (44, 144a, 144b); a resistor-inductor-capacitor resonance load arrangement including a resistor (58, 158a, 158b), an inductor (56, 156a, 156b) and a capacitor (54, 154) and a feedback circuit including at least one feedback resistor (46, 146a, 146b), said feedback circuit being connected between the amplifier input (34, 134a, 134b) and the amplifier output (36, 72a, 72b); wherein the device (2, 2') is arranged to be selectably operable in: a first mode wherein the amplifier (10, 10a, 10b, 10c, 510, 1010, 1110) has first feedback resistance and transconductance values respectively such that the amplifier input impedance and the filter output impedance are substantially the same; and a second mode wherein the amplifier (10, 10a, 10b, 10c, 510, 1010, 1110) has second feedback resistance and transconductance values respectively such that upon connection of a predetermined external impedance matching circuit between the filter (8, 8a, 8b, 8c) and the amplifier (10, 10a, 10b, 10c, 510, 1010, 1110), the amplifier input impedance and the filter output impedance are substantially the same; wherein the second feedback resistance is selected such that a noise figure associated with the device (2, 2') when it is operated in the first mode is substantially equal to the noise figure when it is operated in the second mode with the predetermined external impedance matching circuit connected; wherein the second feedback resistance satisfies the following equation R FR2 = (g m1 R s -1)R L, wherein R FR2 is the second feedback resistance value, g m1 is the first transconductance value, R s is a source resistance value of the input transistor (44, 144a, 144b) and R L is the value of the resistor (58, 158a, 158b) of the resonance load arrangement.