Multimode Low Noise Amplifier Filter With Tunable Transfer Function Characteristics

This article reports on the design and practical development of a multimode low noise amplifier filter (LNAF) capable of single band, concurrent dual band, and an intrinsic switch-off mode of operation with continuous bandwidth (BW) tunability in its passband modes. The proposed multimode LNAF concept is based on a new type of multimode radio frequency (RF) component that comprises a transistor and two complex-matched bandpass filters (BPFs), thus eliminating the need for additional filtering in the RF front end (RFFE). Its modes of operation can be reconfigured by intrinsically switching off the BPFs through transmission zero (TZ) re-allocation and by reconfiguring the transistors’ bias voltages. The TZ flexibility is also exploited for BW tuning due to its minimal impact on the noise figure (NF). The multimode LNAF concept was validated at the 5G FR1 frequency bands n77 and n79 through the design, manufacturing, and testing of one dual-mode LNAF and two quad-mode LNAFs (LNAFs I and II) prototypes that functionalize single-band and concurrent dual-band transfer functions with tunable BW, and switch-off modes of operation.