An amplifier comprises an amplifying element having an input side and an output side; a first transformer on the output side of the amplifying element arranged to mutually couple a fraction of the output current from the amplifying element onto the input side of the amplifying element; a second transformer on the input side of the amplifying element arranged to increase the input voltage on the input side via mutual coupling of its primary and secondary windings; wherein a primary winding of the first transformer is connected to an output of the amplifying element; wherein a secondary windingof the first transformer is ac connected to a secondary winding of the second transformer; and wherein the primary winding of the first transformer is dc blocked from the secondary winding of the second transformer. The negative and the positive reactive feedback loops are not formed from the same trifilar transformer. Therefore, there is no unwanted feedback between the primary and tertiary windings that detracts from the gain and/or impedance-noise matching. The positive reactive loop is provided by the second transformer provided solely on the input side of the amplifying element. The negative reactive feedback loop is provided via the first transformer that provides its feedback to the second transformer without the two transformers being mutually coupled, but with a dc block that maintains the dc isolation across the amplifying element. A significant advantage of this arrangement compared with the trifilar design is that in addition to removing the unwanted coupling between primary and tertiary windings (i.e., selective mutual coupling), the amplifier can be fabricated on chip using one thick RF metal layer fabrication process.