High-speed low-voltage line driver for SerDes applications

• Main Author: Rogers, Michael
• Published: Oxford Brookes University 2009
• Subjects: 621.3815
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.616295

The driving factor behind this research was to design & develop a line driver capable of meeting the demanding specifications of the next generation of SerDes devices. In this thesis various line driver topologies were analysed to identify a topology suited for a high-speed low-voltage operating environment. This thesis starts of by introducing a relatively new high-speed communication Device called SerDes. SerDes is used in wired chip-to-chip communications and operates by converting a parallel data stream in a serial data stream that can be then transmitted at a higher bit rate, existing SerDes devices operate up to 12.5Gbps. A matching SerDes device at the destination will then convert the serial data stream back into a parallel data stream to be read by the destination ASIC. SerDes typically uses a line driver with a differential output. Using a differential line driver increases the resilience to outside sources of noise and reduces the amount of EM radiation produced by transmission. The focus of this research is to design and develop a line driver that can operate at 40Gbps and can function with a power supply of less than IV. This demanding specification was decided to be an accurate representation of future requirements that a line driver in a SerDes device will have to conform to. A suitable line driver with a differential output was identified to meet the demanding specifications and was modified so that it can perfonn an equalisation technique called pre-distortion. Two variations of the new topology were outlined and a behavioural model was created for both using Matlab Simulink. The behavioural model for both variants proved the concept, however only one variant maintained its perfomance once the designs were implemented at transistor level in Cadence, using a 65nm CMOS technology provided by Texas Instruments. The final line driver design was then converted into a layout design, again using Cadence, and RC parasitics were extracted to perfom a post-layout simulation. The post layout simulation shows that the novel line driver can operate at 40Gbps with a power supply of 1 V - O.8V and has a power consumption of 4.54m W /Gbps. The Deterministic Jitter added by the line driver is 12.9ps.