Frequency conversion circuitry (100, 200,300) having an input node for receiving an input signal at a first frequency and an output node for producing an output signal at a second frequency different from the first frequency, the circuitry comprising: a switching/commutating mixer circuit responsive to the input signal for producing a signal at the second frequency, the mixer circuit comprising a plurality of MOSFET pairs (M1+M3, M2+M4), a drain of a first MOSFET (M1, M2) coupled to a drain of a second MOSFET (M3, M4) in each MOSFET pair (M1+M3, M2+M4), wherein an input of the mixer circuit has first and second input nodes, a source of the first MOSFET (M1, M2) in each MOSFET pair (M1+M3, M2+M4) being coupled to the first input node and a source of the second MOSFET (M3, M4) in each MOSFET pair (M1+M3, M2+M4) being coupled to the second input node of the mixer circuit, and wherein the MOSFETs of each of the plurality of MOSFET pairs (M1+M3, M2+M4) are configured to operate at their linear region; first and second oscillator nodes (LO+, LO-) each coupled to a first gate of the first MOSFET (M1, M2) in a respective first pair of the plurality of MOSFET pairs (M1+M3, M2+M4) and to a second gate of the second MOSFET (M4, M3) in a respective second pair of the plurality of MOSFET pairs (M1+M3, M2+M4); a step down impedance transformation circuit coupled between the input node and the input of the mixer circuit for providing input impedance of the mixer circuit lower than impedance at the input node, and a common-base or common-gate amplifier circuit coupled between an output of the mixer circuit and the output node for amplifying the signal at the second frequency produced at the output of the mixer circuit, wherein the output of the mixer circuit has first and second output nodes, the drain of the first MOSFET of the respective first pair (M1+M3) of the plurality of MOSFET pairs (M1+M3, M2+M4) being coupled to the first output node and the drain of the first MOSFET of the respective second pair (M2+M4) of the plurality of MOSFET pairs (M1+M3, M2+M4) is coupled to the second output node of the mixer circuit, the mixer circuit being configured for providing input impedance of the output amplifier lower than the impedance at the input node, and wherein the mixer circuit, the step down impedance transformation circuit and the amplifier circuits are configured for providing a DC current path that allows a DC current to flow from the amplifier circuit via the mixer circuit to the step down impedance transformation circuit, the DC current path including a selected one of the first MOSFET (M1, M2) or the second MOSFET (M3, M4) in each of the plurality of MOSFET pairs (M1+M3, M2+M4) based on a given polarity of the first and second oscillator nodes (LO+, LO-). a switching/commutating mixer circuit responsive to the input signal for producing a signal at the second frequency, the mixer circuit comprising a plurality of MOSFET pairs (M1+M3, M2+M4), a drain of a first MOSFET (M1, M2) coupled to a drain of a second MOSFET (M3, M4) in each MOSFET pair (M1+M3, M2+M4), wherein an input of the mixer circuit has first and second input nodes, a source of the first MOSFET (M1, M2) in each MOSFET pair (M1+M3, M2+M4) being coupled to the first input node and a source of the second MOSFET (M3, M4) in each MOSFET pair (M1+M3, M2+M4) being coupled to the second input node of the mixer circuit, and wherein the MOSFETs of each of the plurality of MOSFET pairs (M1+M3, M2+M4) are configured to operate at their linear region; first and second oscillator nodes (LO+, LO-) each coupled to a first gate of the first MOSFET (M1, M2) in a respective first pair of the plurality of MOSFET pairs (M1+M3, M2+M4) and to a second gate of the second MOSFET (M4, M3) in a respective second pair of the plurality of MOSFET pairs (M1+M3, M2+M4); a step down impedance transformation circuit coupled between the input node and the input of the mixer circuit for providing input impedance of the mixer circuit lower than impedance at the input node, and a common-base or common-gate amplifier circuit coupled between an output of the mixer circuit and the output node for amplifying the signal at the second frequency produced at the output of the mixer circuit, wherein the output of the mixer circuit has first and second output nodes, the drain of the first MOSFET of the respective first pair (M1+M3) of the plurality of MOSFET pairs (M1+M3, M2+M4) being coupled to the first output node and the drain of the first MOSFET of the respective second pair (M2+M4) of the plurality of MOSFET pairs (M1+M3, M2+M4) is coupled to the second output node of the mixer circuit, the mixer circuit being configured for providing input impedance of the output amplifier lower than the impedance at the input node, and wherein the mixer circuit, the step down impedance transformation circuit and the amplifier circuits are configured for providing a DC current path that allows a DC current to flow from the amplifier circuit via the mixer circuit to the step down impedance transformation circuit, the DC current path including a selected one of the first MOSFET (M1, M2) or the second MOSFET (M3, M4) in each of the plurality of MOSFET pairs (M1+M3, M2+M4) based on a given polarity of the first and second oscillator nodes (LO+, LO-).