Digitally Enhanced Wideband I/Q Downconversion Receiver With 2-Channel Time-Interleaved ADCs

The interesting concept of employing in-phase/quadrature (I/Q) downconversion together with time-interleaved analog-to-digital converters allows digitizing very wide instantaneous radio-frequency (RF) bandwidths (BWs) and grants enhanced flexibility in accessing and processing the RF spectrum. Such a structure also inevitably suffers from performance degradation due to the analog components' nonidealities, e.g., frequency response mismatches (FRMs), that ultimately lead to spurious mismatch components that limit the system's dynamic range. Available solutions developed for I/Q mismatches or time-interleaving mismatches alone are not compatible for correcting the FRM spurs in such joint I/Q time-interleaved converter (IQ-TIC) architecture. This brief proposes novel blind FRM identification and correction solutions that are able to suppress all the associated spurs in the considered wideband IQ-TIC architecture. The proposed digital correction solutions are tested and verified using measured hardware data obtained from an experimental platform, exhibiting good FRM spur correction performance with instantaneous BW on the order of 800 MHz. These developments pave the way toward 5G radio communication devices and systems where instantaneous BWs on the order of 1 GHz are envisioned at centimeter- and millimeter-wave frequency bands.