Wideband distributed differential power amplifier utilizing metamaterial transmission line conception with impedance transformation

A differential power amplifier used in a wideband radio frequency (RF) circuit implemented in an integrated circuit (IC), the power amplifier comprising:

• a pair of a first transistor and a second transistor coupled to each other to form a differential amplifier that operates in a range of frequencies from a lower operating frequency (f1) to an upper operating frequency (f2) to provide a relatively linear gain between the lower operating frequency and the upper operating frequency;
• a transformer having a primary winding and a secondary winding with a turn ratio (n) and a coupling coefficient (k), wherein the primary winding is coupled to a first drain terminal of the first transistor and a second drain terminal of the second transistor;
• and
• an output metamaterial transmission line coupled to the secondary winding of the transformer, wherein the output metamaterial transmission line comprises:
• a first inductor and a second inductor having an identical inductance (L1) coupled in series to a first terminal and a second terminal of the secondary winding of the transformer,
• a third inductor coupled to the first terminal of the secondary winding of the transformer, wherein the second inductor is configured to have an inductance (L1_1) that is determined based on L1, n, and k,
• a first capacitor coupled to the third inductor in series and a first output terminal of the differential power amplifier, the first capacitor having a capacitance of C2,
• a fourth inductor coupled to the second terminal of the secondary winding of the transformer, wherein the fourth inductor is configured to have an inductance (L1_1) that is determined based on L1, n, and k, and
• a second capacitor coupled to the fourth inductor in series and a second output terminal of the differential power amplifier, the second capacitor having a capacitance of C2.