Ultrahigh-frequency variable gain amplifier structure

The invention discloses an ultrahigh-frequency variable gain amplifier structure which comprises a first part circuit (100) and a fourth part circuit (400) which are composed of broadband transformermatching networks, and a second part circuit (200) and a third part circuit (300) which are composed of amplitude control modules connected in parallel; the first part circuit (100) completes the matching from a 50 ohm load to an input impedance Rin and realizes the conversion from a single-ended signal RFin to differential signals in+ and in-; the second part circuit (200) is composed of six basic gain units which are connected in parallel and based on a differential common-source amplifier, wherein the normalization size of each basic gain unit is from 1x to 32x; the third part circuit (300)is composed of three improved multiple parallel equivalent structures; and the fourth part circuit (400) completes matching of output impedance Rout to a 50 ohm load, and realizes conversion from differential signals out+ and