Design of a Limiting Amplifier for an Optical Receiver

• Autor(a) principal: Leitão, Renata Santos
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/74921
• topic: CERN; LHC; Optical Receiver; Radiation-tolerant; LA; RSSI; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia Eletrotécnica, Eletrónica e Informática

The HEP experiments that take place at CERN’s LHC demand a multi-gigabit optical link for an efficient transmission of the resulting generated data. An optoelectronic link arises as the best solution given its possibility of working at high data rates and due to fiber’s imunnity to electromagnetic noise. The design of this optical link is particularly demanding due to the stringent data rate specifications (5Gb/s), the BER specification (1012) and the constraints imposed by radiation. In HEP, radiation is always a constraint so, the Optical Receiver circuit must be hardened in order to tolerate that kind of environment - radiation-tolerant. The core of a standard optoeletronic receiver includes a Photodiode, a Transimpedance Amplifier (TIA) and a Limiting Amplifier (LA). This thesis proposes the study and implementation of one of these blocks (LA), as the main focus, as well as the analysis and design of all three other blocks. The two major design constraints regarding the LA are the bandwidth and minimising its power consumption, which were overcome by using two bandwidth enhancement techniques. The circuit yields a bandwidth of 4:8GHz with a power consumption under 19mW. Another fundamental block is the Output Buffer. The major request for this block was maintaining relatively low transition times and improving the signal’s integrity. It has a differential output swing around 400mV with Pre-emphasis levels larger than 130%. The third block is the Received Signal Strength Indicator (RSSI). From a system point of view it is useful to have a measure of the input signal’s power so that the communication channel is used in its full potential. With a power consumption smaller than 600μW the RSSI presents an input dynamic range larger than 50 dB. The fourth block implements a Squelch function, in order to suppress unwanted output toggling due to noise. All these elements were developed in a TSMC 65nm CMOS process with a 1:2V supply voltage.