Self-calibration of input-match in RF front-end circuitry

The input match of RF front-end circuitry can degrade significantly due to process faults and parasitic package inductances at its input pad. The proposed technique ascertains the input match frequency of the circuit by using a built-in self-test (BiST) structure, determines the frequency interval by which it needs to be shifted to restore it to the desired value, and then feeds back a digital word to the low-noise amplifier (LNA), which adaptively corrects its input-match in real-time. The circuitry presented in the paper offers the advantages of low power overheads (the circuits can be powered off when not in use), robustness, no requirements of digital signal processing cores or processors, and fast calibration times (less than 30 μs). This proof of concept is demonstrated by designing a cascode LNA and the complete self-calibration circuit in IBM 0.25-μm CMOS RF process.