Study Of Ultra-wideband General Asynchronous Time Interleaving Sampling Structure And Sampler

In the past decade,the bandwidth of ultra wideband(UWB)signal acquisition system represented by oscilloscope has been rapidly improved,among which system sampling architecture,analog signal sampling(sampler)technology,high speed analog to digital converter(ADC)technology,digital signal reconstuction algorithm,etc.are the four core elements that determine the capability of UWB sampling system.The system sampling architecture can be divided into three types:synchronous time interleaving(STI),asynchronous time interleaving(ATI),and digital band interleaving(DBI).However,these three methods can not cover all the existing sampling system problems.Generally,there are two ways to realize the sampler,namely,sample and hold amplifier(SHA)and track and hold amplifier(THA).So far,there are many research results,but there are few modeling and Analysis on the sampling process and output spectrum characteristics of SHA or THA,which is not conducive to describing the requirements of sampling clock edge steepness,output signal transmission bandwidth and so on.In particular,the existing literature of THA focuses on the realization of a wide working bandwidth with a high sampling rate,which is not conducive to the application of the system,and pay less attention to the unsteady working process from track-phase to hold-phase.In view of the above problems,this paper carried out the following research:1.The mathematical model of sampling process and signal characteristics of sampler is established,and the technical boundary of different kinds of samplers is evaluated;the corresponding relationship between the jitter of sampling clock waveform and phase noise is analyzed,and the mathematical model of the relationship among the frequency spectrum of phase noise,sampling time and time jitter is established.2.A generalized asynchronous time interleaving(GATI)sampling architecture is proposed.GATI architecture is proposed to solve the problems of system synchronization and output signal bandwidth of sampler in the research of photoelectric joint sampling system.The GATI architecture draws on the dual channel ATI's idea of frequency conversion,and expands the number of channels to any numerical case,and represents it in a simple matrix way.Finally,simulation is executed to verity it.3.Several THA chips with low sampling rate and high bandwidth are realized in 0.13um SiGe HBT technology all with clock waveform processing circuit introduced,which include single-channel single-stage structure,single-channel master-slave structure and four-channel master-slave structure.The measured indexes show that under the sampling rate of 2GS/s,the working bandwidth of three THAs reach above 20GHz,which can be directly used for the construction of ultra wideband signal acquisition system.4.A low feed-through single channel master-slave THA chip is implemented in 0.18um SiGe HBT process.instead of cross capacitance feedback method whose effect would decrease with the increase of frequency.The THA adopts a new type of circuit structure with a bandwidth enhancement circuit.The experimental results show that the working bandwidth is above 10GHz at 5GS/s sampling rate,and the simulation results show that the feed-through suppression effect is obvious,about less than half of that of other reported THAs.5.The mathematical model of THA unsteady process from track-phase to hold-phase is established.The understanding of this unsteady process is very important for process selection and circuit design.In this paper,an approximate bandwidth to delay conversion(BTD)method is proposed,and an analytical mathematical model of approximate delay is established to guide the design of the new structure THA chip.