ИСТИНА

Traditional approach for microwave photonic ADC is based on processing in time domain, where every time-neighbor sample of input signal is handled by its own channel. However, this method typically requires high precision and expensive photonic components: femtosecond pulse source (mode-locked laser) with ultra-low timing jitter, optical fibers with high precision lengths, balanced photodetectors and others, which form together very unstable and bulky device. For the input signals with limited bandwidth, another approach can be used, in which the incoming broadband microwave signal is divided into several channels where optical filtering and down conversion are implemented in frequency domain for further processing by low speed electrical ADCs. Performance capabilities for such microwave photonic ADC are derived with numerical simulations and compared with experimental results. It is shown that, for modern photonic components, 8-10 effective bits can be achieved in the digitized signal.