Research Of SiGe BiCMOS High-speed A/D Converter

With the development of digital communication technology,especially high speed digital system,it is necessary to chang analog signal into digital signal immediately for realtime processing,and the speed of A/D Converter(ADC) is becoming higher and higher.Recently abroad,research of ADC has been concentrating on high speed and high resolution,which are just the two deficiency in our country.In this dissertation, I present a high-speed 8-bit SiGe BiCMOS A/D converter with conversion rate over 1GHz.In this design,I use the two-step flash architecture with analog-switches,which has high conversion speed,high resolution as well as overcomes the shortcomings of conventional subranging ADC such as difficulty of designing and fabricating.A high speed SHA for pipeline ADC uses HBT cascade and PMOS load with the gain boosting structure to improve its speed and output swing.A high speed THA is also proposed for this two-step flash ADC.A high speed voltage fully differntial comparator with four input uses an excellent preamplifier to improve its high frequency performance.The whole circuit uses TSMC 0.35um SiGe BiCMOS technology with 3 poly layers and 3 metal layers.Hspice simulation shows that the circuit can work well to meet my requirments.At last,parts of layout are realized.