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SCUBA-2 Systems Review Multi-Channel Electronics. Hilo, Hawaii June 19-23, 2006. MCE Overview. Each MCE reads signals from a 41 ×32 pixel sub-array. 4 readout cards (RC) that each read 8 output lines through 14-bit 50MHz ADCs.

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Scuba 2 systems review multi channel electronics

SCUBA-2 Systems ReviewMulti-Channel Electronics

Hilo, Hawaii

June 19-23, 2006


Mce overview
MCE Overview

  • Each MCE reads signals from a 41×32 pixel sub-array.

  • 4 readout cards (RC) that each read 8 output lines through 14-bit 50MHz ADCs.

  • One address card (AC) that asserts each of 41 addresses at ~850kHz.

  • One clock card (CC) that interprets the commands and synchronizes all the cards.



Synchronizer box

 Commands

? get_Status

go enable DV-outputs

st disable DV-outputs

rt RTS mode

(external DV supplied)

fn n set frame num. to  n

fr n set free-run counter to n < 4095

nr n set num. of rows to n < 63

rl n set row_len to n < 4095

re reset

ps power status

dpa disable power for all 8 MCEs

dpun disable power for MCE(n)

Status

Mancho_Enable = ON

DV_Mode = FRUN_DV

FRUN_COUNT = 47

row_len = 64

num_row = 41

ACDCCU_onoff = 0X00  

Synchronizer Box


Output of synchronizer to mce
Output of Synchronizer to MCE

39

33

1

0

Fr. No.

DV

sync


Scuba 2 systems review multi channel electronics

-

Cold Electronics

Warm Electronics (MCE)

TES Bias BC2

data_mode

2:filtered

14b

2n

SQ1_FB

D/A

LPF

SA_BIAS

2m

data_mode

1:feedback

15 kΩ

PID

(110 Ω)

14b

data_mode

0: error

SQ1

+

A/D

A=195

Dout

-

SQ2

ADC_OFFSET RCn

0.1 Ω

data_mode

3: raw

SA_OFFSET RCn

(110 Ω)

SA_FB BC1

SQ2_BIAS (SB) BC3

SQ2_FB BC2

SQ1_BIAS (RS) AC


Squid characterization using mce
Squid CharacterizationUsing MCE

  • Sweep the feedback current of each stage across its full range and adjust the lower-stage feedback to keep the series-array output voltage constant.

    • Sweep Series-Array(SA) feedback

      • Choose SA_BIAS, target voltage

    • Sweep SQ2 feedback and adjust SA feedback

      • Choose SQ2_BIAS, SA_FB

    • Sweep SQ1 feedback and adjust SQ2 feedback

      • Choose SQ1_BIAS, SQ2_FB, SQ1_FB

    • Turn on the servo loop

    • Sweep through TES_bias


Scuba 2 systems review multi channel electronics


Squid characterization using mce1
Squid characterization Using MCE

  • Linux shell scripts that call C functions to issue commands to MCE

  • Areas of improvement:

    • Implementation in C

    • RTL PC reliability:

      • More reliable PCI card with additional diagnosis features

      • More robust Operating System: e.g., Fedora

      • Modular architecture (e.g., PCI Card driver independent of DRAMA and DAS)


Science data mode
Science Data Mode

  • In normal data mode the first-stage squid feedback signal, which is read at 20 kHz, is low-pass filtered and reported at every data valid pulse (DV), approximately at 200 Hz.

  • The filter is a 4-pole Butterworth filter with a cutoff frequency of ~50 Hz.

  • For each DV pulse, the MCE reports 4184 32-bit values plus a header.


Engineering readout modes
Engineering Readout Modes

In addition to ‘Science Data Mode’ we have a number of readout modes to help diagnose performance.

  • Internal DV pulses up to 1.4 kHz. Normal format.

  • Combined Feedback and Error signals in 32b words

  • 41×8 pixels sampled at 50 MHz, in a burst.

  • Reduced array area at a rate > 1.4 kHz

  • Error Signals only (ie not the Feedback signal)

    Combinations of these options are possible.

    Question: Can the Data Pipeline handle any of these?


Mce power shutdown
MCE Power Shutdown

MCE shuts itself down only if:

  • Unacceptable high voltages/currents are detected.

  • Unacceptable high temperatures inside the MCE are detected.

    MCE status prior to auto-shutdown is recorded into an EEPROM.

    AC/DC unit shuts down if over temperature is detected.