In our daily life, we have smart phones, smart TVs, or even auto-pilot smart cars in the future. In our engineer careers, we have smart antenna, smart baseband chips, but we still need auto-calibration smart RFICs. Especially for millimeter-wave RFICs with giga-hertz bandwidth, the narrow-band baseband calibration cannot compensate the broadband AM/AM or AM/PM non-ideal properties.
For future multi-band multi-standard radio, auto-band-switching is an essential function to optimize RF performance and to simplify the system control interface. A Miller-divider-type frequency sensor can be used to detect the frequency of input signal and perform auto-band-switching inside RFIC without any system control bits. For parametric sensitive 3rd-order nonlinearity, we need parametric-insensitive calibration methods to compensate the non-ideal behavior within RFIC. For millimeter-wave phase array system, the phase error comes from not only phase shifters but also other functional blocks, like variable gain amplifier (VGA), during phase shifting and gain compensation. We need a phase-error calibration method to compensate the phase error from all RFIC blocks.
To optimize system EVM performance, IQ modulator/demodulator are the key components to compensate IQ mismatch at RF frequency, which is also the enabling technology for gigabit high-QAM wireless links. The load-insensitive indicator is used to evaluate different IQ topologies. For IQ self-calibration at RF frequency, the phase compensation has more design challenges than the amplitude calibration, so composite right/left-handed transmission line, switching capacitor array, and phase shifters have been proposed in the IQ phase calibration. All above built-in self-calibration and auto-switching functions are innovated to pave the road to the next-generation millimeter-wave 5G mobile smart RFIC.