1. ANITA RF Conditioning and Digitizing Gary S. Varner University of Hawai, i, Manoa ANITA Collaboration Meeting UC, Irvine 24,25 November 2002

2. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 1 Topics RF Signals –Noise Limited RF Electronics –Optimum SNR –Triggering –HS Transient Digitizers Prototypes –STRAW2 –DRS –Advanced ATWD R&D Plans (for discussion)

3. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 2 Askaryan Signature Significant signal power at large frequencies Strong linear polarization (near 100%)

4. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 3 Single Point Measurement Maximize R for better pointing… trigger latency R Empirically determined Decoherence Freq. Material, aperture Squeeze all possible info.

5. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 4 RF Transient Recorder Specs  >= 1GHz analog input bandwidth (300-1200MHz)  multi-GSa/s sampling rate (Nyquist limit ideal)  minimum phase distortion for clean polarization  maximum dynamic range (>= 9 bits)  internal Analog to Digital Conversion (ADC)  short record length (100-200ns if optimally matched)  self-triggering with fine threshold adjustment  bi-polar triggering  deadtimeless  conclude multi-hit buffering needed

6. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 5 Proposed Signal Flow LNA Gain Digitize Trigger [GHz].3 1.2.3 1.2

7. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 6 Straw-man Instrumentation Trigger /Digitizers

8. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 7 In principle, can do brute force with off-the-shelf ADCs/backend processing (POWER! But other issues) A number of SCA designs: –DSC (samples obtained, to be tested) –KEK AMC –STRAW2 (SalSa prototype) –Advanced ATWD (Kleinfelder [UCI]) Space/Balloon Transient RF specific: –>1GHz analog input bandwidth –Self-triggering –Low power Possibilities

9. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 8 High-speed Digitizers DRC/ DRS close Analog BW not eval.

10. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 9 Domino Ring Sampler (DRS) input Free running domino wave, stopped with trigger Sampling speed 2 GHz (500ps/bin), trigger gate sampling gives 50ps timing resolution 1024 bins  150ns waveform + 350ns delay Free running domino wave, stopped with trigger Sampling speed 2 GHz (500ps/bin), trigger gate sampling gives 50ps timing resolution 1024 bins  150ns waveform + 350ns delay Information courtesy of Stefan Ritt (PSI): For further info.: http://meg.web.psi.ch/doc/talks/s_ritt/may02_triumf/meg.ppt If can keep the sampling jitter small enough (or can measure), no need for a TDC! Switched Capacitor Array (SCA)

11. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 10  Domino Sampling Chip C. Brönnimann et al., NIM A420 (1999) 264 Existing: 0.5 – 1.2 GHz sampling speed 128 sampling cells Readout at 5 MHz, 12 bit ~ 60 $/channel Needed: 2.5 GHz sampling speed Circular domino wave 1024 sampling cells 40 MHz readout Existing: 0.5 – 1.2 GHz sampling speed 128 sampling cells Readout at 5 MHz, 12 bit ~ 60 $/channel Needed: 2.5 GHz sampling speed Circular domino wave 1024 sampling cells 40 MHz readout

12. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 11 STRAW2 Specifications Unique in this design is the triggering requirements –High freq and bipolar Large latency strategy: –Multiple buffering

13. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 12 STRAW2 Architecture 0.25  m TSMC process

14. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 13 Ring Oscillator in 0.25  m CMOS

15. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 14 Analog Input Bandwidth! Many examples of high sampling rate, but: –PMT readout –Wireless (2.5GHz) –Very narrow BW –Naïve calculation  phase inductance –3-D Simulation PCB, Package, bond wires BGA necessary? What is fundamental limit ComponentLength/areaUnitFactorFunit Total [fF] Input traces5cm0.2pF/cm1000w.a.g. bonding wire150mil0.3pF/wire300w.a.g. input pad60um^2187fF/pad187Tanner input protection594 1.1pF/ckt1100SPICE stripline area2500um^243 aF/um^ 2107.5MOSIS stripline fringe5mm60aF/um300MOSIS Switch Drains256switches5.6fF/drain1433.6SPICE Open Switches6open87fF/gate522SPICE TOTAL 4.9501pF

16. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 15 RF Coupling Simulation die on-chip 50  stripline Utilizes the LC program (FTDT algorithm) –Cray developed, available for free under Linux Bonding wires

17. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 16 S-Parameters VSWR: 1.8 [1GHz] 1.9 [2GHz]

18. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 17 Logging Performance

19. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 18 Self-Triggering

20. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 19 Simulation Results Use simulated high freq. Response from beamtest data: –works

21. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 20 STRAW2 Chip Submitted for Fab.: 4 Nov. 16 Channels of 256 deep SCA buckets Self-Triggered Recorder Analog Waveform (STRAW) Optimized for RF input Microstrip 50  Record length: 128-256ns Self-Triggering: Target input Bandwidth: >700MHz -LL and HL (adj.) for each channel Sampling Rate: 1-2GSa/s (adj.) -Multiplicity trigger for LL hits On-chip ADC: 12-bit, >2MSPS External option: MUXed Analog out Sampling Rates >~8GSa/s possible w/ 0.25  m process 8192 analog storage cells Die:~2.5mm 2

22. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 21 Cosmic-ray Radio Testbed Stage 2: Replace TDM with STRAW2 –~200 total antenna signals – get rid of delay cables

23. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 22 Evaluation Trigger /Digitizers

24. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 23 Readout Board/RF prototype Strong disincentive to purse a “full card” development to start with 10k$ parts!

25. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 24 Details…documentation Push to document these details

26. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 25 R&D into critical (non-standard) components: –Strong need in other (e.g. precision timing) applications –Not needed for self-triggering/high analog BW (PMTs) –Emphasis on low-power Plans: –STRAW2 Testing (packaged parts ship 12/19) –ANITA evaluation board/backup ADCs –Adv. ATWD Prototype (common START ready for fab.) Discussion: (see next slide) Preliminary Summary

27. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 26 Time scale for custom component development –STRAW2 appropriate triggering architecture? Really need trigger waveform recording? –Sample depth/rate and bandwidth for ATWD? –Multi-buffering scheme acceptable? –Still consider RF down-conversion/comm. ADCs? Many disadvantages (large BW DCV, power) Viable fallback? Plans: –STRAW2 Testing (packaged parts ship 12/19) –ANITA evaluation board/backup ADCs –Adv. ATWD Prototype (proto. Waiting for $$) Discussion Items

28. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 27 3 Designs Similar 16 cells All paracitics included Domino speed: 1.5-2.2 GHz 16 cells All paracitics included Domino speed: 1.5-2.2 GHz 10 GHz? TSMC 0.25  m AMC:

29. Gary S. Varner, ANITA Collaboration Meeting @ UC Irvine, November 2002 28 KEK AMC Analog Memory Cell (AMC) –Common platform –Original AMC follow-on –Super Belle and JHF 0.5  m: LSB ~200ps 0.35  m: LSB ~100ps?