| Signal processing and transmission are what digital system mainly do. Generally, signal processing speed is growing faster than signal transmission, which makes link design a bottleneck in high performance digital system integrating. With the increase of bandwidth demand, the parallel interface need more pins and signal attenuation become a fatal problem while data rate is beyond 1Gbps. Under this background the high speed serial link based on SerDes(Serializer,De-serializer) technique become mainstream nowadays, which has been widely used in data center, router, PCB and chip to chip interface. As a mixed signal circuit system, SerDes is invovled with analog and custom digital design methodology. Besides, SerDes deals with data rate up to tens of Gbps, more than 10 times CPUs do, which leads to signal integrality problems such as channel attenuation and ISI, making SerDes design more complicated. Our domestic reserch is at primary stage.Based on needs of SerDes independent research and development, by using a 40 nm COMS process, this thesis has designed a programmable pre-emphasis transmitter in SerDes, with functions such as synchronizing physical layer data with data link layer, serializing 10/20 bits parallel sinal into 1 bit, pre-emphasizing serialized signal in order to compensate high frequency attenuation. The design has realized programmable pre-emphasis and output swing by 6 and 5 bits digital control. The main work and contributions of this thesis include followings:1. SerDes design basis has been studied, including transmission line modeling, high frequency attenuation and compensation theory. Custom digital design and analog design methodology in ultra-deep submicron process have been expatiated. Mixed signal design platform has been founded.2. Transmitter specification has been analysed, system overall structure and partition was given, detailed circuit design such as synchronization, common mode FSM, serializer circuits and driver, etc. have been carefully described.3. Digital tuning is used in driver’s programmable design, making a more robust and flexible structure than using analog control.4. Simulation results showed that this transmitter is able to work at 2.5-6.25 Gbps, with programmable pre-emphasis range of 0-6dB and output swing range of 0-1.3V, which meet specifications of high speed serial link standards such as PCIE2.1 and RapidIO2.2. |
