Design and Fabrication of a Radiation-Hard 500-MHz Digitizer Using Deep Submicron Technology

Transcription

1 Design and Fabrication of a Radiation-Hard 500-MHz Digitizer Using Deep Submicron Technoogy K.K. Gan The Ohio State University January 10, 2004 K.K. Gan, M.O. Johnson, R.D. Kass, A. Rahimi, C. Rush The Ohio State University S. Smith SLAC K.K. Gan US LC Conference 1

2 Outine NLC Requirements ADC Design Progress Report Pans K.K. Gan US LC Conference 2

3 Beam Position Monitor Requirements at NLC NLC wi coide 180-bunch trains of e - and e + : n bunch spacing: 1.4 ns n aignment of individua bunches in a train: < 1 mm n BPM determines bunch-to-bunch misaignment ] high bandwidth kickers bring the train into better aignment on next machine cyce ] muti-bunch BPM system with digitizers: M 11-bit effective resoution M 500 MHz bandwidth M 2 G sampes/s K.K. Gan US LC Conference 3

4 Requirements of NLC Digitizers Function Qty. Resoution Bandwidth Comments (eff. bits) (MHz) LLRF Contro 13, Sighty beyond state-of-the-art Structure BPM 22, Existing technoogy Qaud BPM 10, Existing technoogy Muti-bunch BPM 1, We beyond state-of-the-art Tota 46,200 important to demonstrate feasibiity of high speed/resoution digitizers ] redesign of ow eve RF technoogy is needed without the digitizers K.K. Gan US LC Conference 4

5 Proposa design a digitizer chip using deep-submicron technoogy (0.25 mm) n use encosed ayout transistors and guard rings ] radiation hard: > 60 Mrad ] no need for costy shieding and ong cabes ] readiy access to eectronics for testing and maintenance extensive experience in chip design using Cadence n designed radiation-hard chips for CLEO III, ATLAS, CMS why OSU is interested? n hep to sove a chaenging NLC probem n potentia appications in HEP 2002 Hotkamp Committee ranking: 2 on scae of 1 to 4 (owest) ] funded for K.K. Gan US LC Conference 5

6 12-bit Pipeined Digitizer 13 bit: round to 0 or 12 bit input crudey digitized by 1st 3-bit ce ] digitized vaue subtracted from input ] difference is ampified by 8 and sent to 2nd 3-bit ce K.K. Gan US LC Conference 6

7 Digitizer for Muti-bunch BPM most chaenging digitizer: 11 bit, 2 G sampes/s, 500 MHz bandwidth input: sequence of doubets at 1.4 ns batch spacing n n characterize with one parameter: puse height minimum samping: 1/1.4 ns = 714 MHz ] intereaving 3 digitizers for redundancy ] 2 G sampes/s K.K. Gan US LC Conference 7

8 Precision submicron CMOS suppy votage: 2.5 V ] differentia signa: ~ 1.6 V fu swing ] LSB: 1.6 V/2 12 = 390 mv ] stabiity/accuracy of comparator threshods, ampifier & S/H gains, charge injection: 195 mv = 0.5 LSB = 0.5/2 12 = 0.012% K.K. Gan US LC Conference 8

9 Fabrication Process gain-bandwidth requirement: n assume 0.7 ns for sampe and 0.7 ns for hod n setting to 0.5 LSB for 12-bit digitizer requires 9t: 0.5/2 12 ~ e -9 ] t = 0.7 ns/9 = 78 ps ] rise time = 2.2 t = 171 ps ] gain x bandwidth = 8 x 1/2pt = 16.4 GHz ] IBM process SiGe BiCMOS 6HP/6DM via MOSIS: 40 GHz NPN bipoar transistors K.K. Gan US LC Conference 9

10 3-Bit Ce K.K. Gan US LC Conference 10

11 3-Bit Ce Status simuated with Cadence 4 4 sampe/hod + fash ADC/fip-fop: designed/simuated from schematic with parasitic capacitances n q mutipexer: ogic is fast but somewhat noisy op-amp + encoder: sti use idea devices in simuation K.K. Gan US LC Conference 11

12 Sampe/Hod Status design and simuated from schematic with parasitic capacitances 4 switch-on resistance sma enough to aow 9t in 700 ps 4 switching offset (noise) argey canceed with dummy switch: n 100 mv ] 1 mv K.K. Gan US LC Conference 12

13 Cadence Simuation of Sampe/Hod Ampifier: idea Ampifier: current design switch charge injection ampifier signa not yet sette to 0.5 LSB in 0.7 ns K.K. Gan US LC Conference 13

14 Simuation of Ampifier rise time: 186 ps n goa: 171 ps: precision at 0.7 ns: 298 mv 270 mv ª 2-10 ] need 4x improvement for 12-bit precision K.K. Gan US LC Conference 14

15 Pans Year : n compete design of ampifier + 3-bit ce Year : n ayout, submission, and testing of the buiding bock circuits n radiation hardness tests n continued system design of a prototype 11-bit digitizer K.K. Gan US LC Conference 15