Highly Linear Broadband Photonic-Assisted Q-Band ADC

Abstract

A highly linear broadband photonic-assisted analogto-digital converter (ADC) based on high-frequency optical sampling utilizing a dual output Mach-Zehnder modulator operating with signal frequencies up to 50 GHz is presented. The pulses employed in the optical sampling were generated by a cavity-less pulse source operated at 10 GHz in preference to conventional mode-locked lasers. The optical sampling front-end greatly extends the operational frequency range of the Nyquist limited electronic digitization back-end. The performance of the sampling system is characterized with 7.1 effective number of bits (ENOBs) at 40 with 5 GHz fully accessible bandwidth, and greater than 99 dB•Hz 2/3 spurious free dynamic range for the 30-40 GHz frequency range. Furthermore, more than 8 ENOB was achieved by reducing the effective bandwidth to 1 GHz with a digital filter, demonstrating the additional advantage of using a higher sampling rate compared to previous demonstrations. A new figure of merit of photonicassisted sub-sampled ADCs is also presented accompanied with a comparison to previous implementations.

Broadband Photonic Down-Conversion Preprocessor for ADC With Arcsine Equalization

“…The numerical simulation is based on Eq. (22)- (23) with no mathematical approximation, and the values of parameters in the simulation are determined by matching the results of the first experiment point and the simulation with the same M.…”

“…There have been some well-known discussions on the figure of merit (FOM) of Nyquist sampling systems or bandpass sampling systems [23], [24], which help to characterize the performance of the whole system from perspectives of carrier frequency, bandwidth and precision. However, the timing jitter and phase noise in the previous definitions are treated as exogenous variables which are not correlated with the repetition rate of the clock.…”

“…The blue lines are based on simulation results from Eq. (22)-(23) with no approximation and the red lines are based on the estimation results from Eq. (33)-(34).…”

Influence of the Demultiplexer on Channel-Interleaved Photonic Analog-to-Digital Converters

“…7and Eq. (10). It is clear that the flatness of output power is improved with the decrease of FoM in the whole frequency range of 20 GHz.…”

“…PADC schemes can be divided into three types: photonic assisted PADCs, photonic sampled and digitized PADCs [7,8], as well as photonic sampled and electronic digitized PADCs [4]. Among these types, the photonic sampled and electronic digitized PADC has become the mainstream scheme because it combines the advantages of photonics in wideband processing and that of electronics in high precision quantization [9][10][11][12][13][14]. The photonic sampled and electronic digitized PADC scheme typically contains a demultiplexer to match the photonic sampling rate and the electronic quantizing rate, thus it can also be classified as channel-interleaved PADC (CI-PADC) [15,16].…”