Frequency-Interleaved ADC with RF Equivalent Ideal Filter for Broadband Optical Communication Receivers

To process an ultra-wideband signal with narrower-band analog-to-digital converters (ADCs), frequency-interleaved (FI) receiver technique that divides an ultra-broadband signal to narrower-band signals has been reported to date. Conventional FI ADCs use analog filters such as LC filters to divide an ultrawideband signal to separated narrower band signals. However, aliasing and level deviation of the signals that occurs in crossover frequency region of the filters degrades the signal transmission quality of the receivers that use FI ADCs. To mitigate this degradation digital signal processing technique to compensate the distortion due to the aliasing and level deviation has been reported. However, the compensation of the aliasing and level deviation need large-scale signal processing. In addition, degradation in signal transmission quality due to decrease in signal to noise ratio and distortion due to nonlinearity caused by the level deviation cannot be removed completely. To omit these degradations and improve the signal transmission quality we propose FI ADCs with an RF equivalent ideal filter (EIF). Computer simulation with ideal circuit components shows a potential to have an excellent band-separation capability and highly-accurate signal transmission quality without large-scale signal processing for the distortion compensation.