Is RF doomed to digitization? What shall RF circuit designers do?

To support the ever-increasing levels of system-on-chip (SoC) integration required by the consumer insatiate appetite for sophisticated yet cheap mobile phones and internet devices, the RF circuit design has recently been moving to the finer CMOS process geometry nodes. There, it can harness the enormous potential of nearly free digital logic and memory. Enter the digital assistance of RF, which offers calibration, compensation, linearization and predistortion of linear devices, which can boost the RF system performance to the point that it is now better and more reliable than with the conventional approaches. The related field of RF built-in self-test (RF-BIST) allows for an RF-SoC to exploit the power of digital signal processing to autonomously test its own RF almost for free. Enter “digital RF”, which transforms the continuous-time analog RF functionality into digitally-intensive or even all-digital implementations. With the transition frequency f_T of over 200MHz in 40nm CMOS, the RF circuits operating at 2GHz now feel just almost like the low-frequency mixed-signal circuits of the past.