Nowadays the increasing growth of big data applications, high serial data rates communications and cloud computing requires high bandwidth wireline performances. The most common metal connections are the coppers type, but their signal’s losing is strongly frequency dependent. The optical interconnections are affected too of the frequency losing but in a minor quantity, for this reason they transport wideband signal over long distance. The optical links are more popular for the high data rate and remote communications. However, the implementation of optical system has many challenges about the sensitivity, the power consumption and the thermal design power constrains of the package. In order to improve more the data rate, in the 2005 the optical communications were associated to coherent modulations that has the high advantage to improve the spectral efficiency of the data [1]. Nowadays the most used technology in optical receiver circuits is the bipolar, due to the high bandwidth and low noise, but in coherent optical receiver the Digital Signal Processing has a very important role to decode the symbol and solve impairments like chromatic and polarization mode dispersion and group delay distortion, and the BiCMOS technology cannot be integrated with the DSP. This research is focused on analyzing the implementation in 28nm CMOS technology of the transimpedance amplifier (TIA) used to convert the photodiode current to voltage. The most critical performances of the TIA usually are the bandwidth and the noise, for that reason at the beginning I analyzed this tradeoff in the most commonly used topology, and I studied the bandwidth extension techniques present in literature. After that two design of TIAs has been realized: the first one uses the complementarity typical of the CMOS to improve the noise performances of the Common Gate topology, while in the second design I proposed a new technique to extend the bandwidth relaxing the tradeoff bandwidth/noise with the cost of higher power consumption. In the thesis is also reported a work realized in collaboration with Lorenzo Gnaccarini for the design of a Closed Loop Variable Gain Amplifier as alternative topology to the traditional Gilbert Cell VGA for enhanced distortion performances.

Nowadays the increasing growth of big data applications, high serial data rates communications and cloud computing requires high bandwidth wireline performances. The most common metal connections are the coppers type, but their signal’s losing is strongly frequency dependent. The optical interconnections are affected too of the frequency losing but in a minor quantity, for this reason they transport wideband signal over long distance. The optical links are more popular for the high data rate and remote communications. However, the implementation of optical system has many challenges about the sensitivity, the power consumption and the thermal design power constrains of the package. In order to improve more the data rate, in the 2005 the optical communications were associated to coherent modulations that has the high advantage to improve the spectral efficiency of the data [1]. Nowadays the most used technology in optical receiver circuits is the bipolar, due to the high bandwidth and low noise, but in coherent optical receiver the Digital Signal Processing has a very important role to decode the symbol and solve impairments like chromatic and polarization mode dispersion and group delay distortion, and the BiCMOS technology cannot be integrated with the DSP. This research is focused on analyzing the implementation in 28nm CMOS technology of the transimpedance amplifier (TIA) used to convert the photodiode current to voltage. The most critical performances of the TIA usually are the bandwidth and the noise, for that reason at the beginning I analyzed this tradeoff in the most commonly used topology, and I studied the bandwidth extension techniques present in literature. After that two design of TIAs has been realized: the first one uses the complementarity typical of the CMOS to improve the noise performances of the Common Gate topology, while in the second design I proposed a new technique to extend the bandwidth relaxing the tradeoff bandwidth/noise with the cost of higher power consumption. In the thesis is also reported a work realized in collaboration with Lorenzo Gnaccarini for the design of a Closed Loop Variable Gain Amplifier as alternative topology to the traditional Gilbert Cell VGA for enhanced distortion performances.

Design of Transimpedance Amplifiers for Coherent Optical Communications in 28 nm CMOS Technology

ASCHEI, LAURA
2022

Abstract

Nowadays the increasing growth of big data applications, high serial data rates communications and cloud computing requires high bandwidth wireline performances. The most common metal connections are the coppers type, but their signal’s losing is strongly frequency dependent. The optical interconnections are affected too of the frequency losing but in a minor quantity, for this reason they transport wideband signal over long distance. The optical links are more popular for the high data rate and remote communications. However, the implementation of optical system has many challenges about the sensitivity, the power consumption and the thermal design power constrains of the package. In order to improve more the data rate, in the 2005 the optical communications were associated to coherent modulations that has the high advantage to improve the spectral efficiency of the data [1]. Nowadays the most used technology in optical receiver circuits is the bipolar, due to the high bandwidth and low noise, but in coherent optical receiver the Digital Signal Processing has a very important role to decode the symbol and solve impairments like chromatic and polarization mode dispersion and group delay distortion, and the BiCMOS technology cannot be integrated with the DSP. This research is focused on analyzing the implementation in 28nm CMOS technology of the transimpedance amplifier (TIA) used to convert the photodiode current to voltage. The most critical performances of the TIA usually are the bandwidth and the noise, for that reason at the beginning I analyzed this tradeoff in the most commonly used topology, and I studied the bandwidth extension techniques present in literature. After that two design of TIAs has been realized: the first one uses the complementarity typical of the CMOS to improve the noise performances of the Common Gate topology, while in the second design I proposed a new technique to extend the bandwidth relaxing the tradeoff bandwidth/noise with the cost of higher power consumption. In the thesis is also reported a work realized in collaboration with Lorenzo Gnaccarini for the design of a Closed Loop Variable Gain Amplifier as alternative topology to the traditional Gilbert Cell VGA for enhanced distortion performances.
Nowadays the increasing growth of big data applications, high serial data rates communications and cloud computing requires high bandwidth wireline performances. The most common metal connections are the coppers type, but their signal’s losing is strongly frequency dependent. The optical interconnections are affected too of the frequency losing but in a minor quantity, for this reason they transport wideband signal over long distance. The optical links are more popular for the high data rate and remote communications. However, the implementation of optical system has many challenges about the sensitivity, the power consumption and the thermal design power constrains of the package. In order to improve more the data rate, in the 2005 the optical communications were associated to coherent modulations that has the high advantage to improve the spectral efficiency of the data [1]. Nowadays the most used technology in optical receiver circuits is the bipolar, due to the high bandwidth and low noise, but in coherent optical receiver the Digital Signal Processing has a very important role to decode the symbol and solve impairments like chromatic and polarization mode dispersion and group delay distortion, and the BiCMOS technology cannot be integrated with the DSP. This research is focused on analyzing the implementation in 28nm CMOS technology of the transimpedance amplifier (TIA) used to convert the photodiode current to voltage. The most critical performances of the TIA usually are the bandwidth and the noise, for that reason at the beginning I analyzed this tradeoff in the most commonly used topology, and I studied the bandwidth extension techniques present in literature. After that two design of TIAs has been realized: the first one uses the complementarity typical of the CMOS to improve the noise performances of the Common Gate topology, while in the second design I proposed a new technique to extend the bandwidth relaxing the tradeoff bandwidth/noise with the cost of higher power consumption. In the thesis is also reported a work realized in collaboration with Lorenzo Gnaccarini for the design of a Closed Loop Variable Gain Amplifier as alternative topology to the traditional Gilbert Cell VGA for enhanced distortion performances.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11571/1453104
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