Microwave photonics scanning channelizer with digital image-reject mixing and linearization

Microwave photonics scanning channelizer with digital image-reject mixing and linearization is investigated by employing a cascaded distributed feedback semiconductor laser (DFB) operating at stable locking dynamics when subjected to flat optical frequency comb (OFC) injection. The OFC injection locking (OIL) provides a high-quality coherent optical local oscillator with ultra-broadband tuning capability by demultiplexing and amplifying individual comb from densely spaced OFC. The channelizer receiver scans the whole frequency range at discrete steps through a single tunable heterodyne receiver and a single ADC, thus reducing the SWaP and increasing agility. By introducing the digital Hartley structure image-reject mixing (IRM), the amplitude and phase imbalance of the IQ channel are easily compensated, resulting in a high image rejection ratio (IRR) up to around similar to 50 dB for all channels. Furthermore, a novel digital linearization technique is employed to suppress third-order intermodulation components by more than 19.43 dB while improving the spurious free dynamic range (SFDR) by 16.1 dB The analysis confirms the scheme's capability for detecting signals from 1.5 GHz to 43.5 GHz and beyond with excellent performance. The proposed channelizer can find applications in future wideband RF systems, including 5G and beyond wireless communications, electronic warfare, and radars.