| 摘要 |
Embodiments in accordance with the invention allow for direct digitization of wideband RF signals without the need for down conversion or the use of mixers. In one embodiment, a preprocessed input analog signal is applied to three wideband Mach-Zehnder interferometers (MZI), e.g., modulators, to amplitude modulate a continuous wave laser signal. A photodetector is used at the output of each interferometer to convert the amplitude modulated optical signal into an electrical signal. This is followed by an amplifier and a low-pass filter (LPF) to increase the signal level and to reduce the noise. A small mi comparator bank at the output of each LPF is clocked at the sampling frequency and encodes the electrical signal from each detector into a thermometer code that represents an integer value within the modulus. A field programmable gate array (FPGA) then combines the thermometer-code from each comparator bank in order to generate a more convenient 6-bit binary representation, i.e., a digital output. |
