MIT Lincoln Laboratory999999-1

XYZ 04/21/23

APS-2 Chip: W21 R5C6Has Quartz Support

MIT Lincoln Laboratory999999-2

XYZ 04/21/23

APS-2 Chip W3 R3C3No Quartz Support

999999-3XYZ 04/21/23

MIT Lincoln Laboratory

APS-2 Test Status

V. Suntharalingam

29 February 2008

MIT Lincoln Laboratory999999-4

XYZ 04/21/23

Last Time:

• We showed that the capacitor was present in the pixel

– RSTG1 Is ON; RSTG2 Is Pulsed (Active Low)

– VRST1 = 100MHz Input Sine Wave

• Output signal swing ~1V and pixel saturates in about 1.75sec (RT, not light tight)

• Temporal noise measurements made on a new chip were ~1.5mVrms

OF

F

ON

OF

F

ON

VoutRSTG1RSTG2VRST1

VRST2 = 1.5V

MIT Lincoln Laboratory999999-5

XYZ 04/21/23

This Time:

• Test board modified to permit input of VRST2 waveform– 2kHz sine wave used to verify FFT algorithm (noisy function generator source)– Alternatively, DC level for VRST2 can still be supplied by National Instruments card

• Test software modified to implement software-controlled ADC anti-aliasing filter (low pass filter before A-to-D)

• Pattern files generated to readout one pixel 65,536 times– Sometimes column sample/hold (clamp/sample) is asserted once per row

• Matlab code written to do FFT• Test conditions -- Single Pixel r95c159 from Chip: 21A w3 r2c3 no quartz support

– Covered with black cloth in dark room, but stray light could be a problem!– Test points for bias supplies verified at board (confirms no droop)– VRST1 = VRST2 = VSCP =1.5V– VDDA = VDDD = VDD_ESD = 3.3V– VSIG_out/10kohm to -4V– VPDBIAS = 5V for scope– ICMPIX = 5uA, ICMNCOL = 10uA, ICMP = -20uA

• Goal of this work (in progress) is to extract noise power spectrum for pixel and rest of analog output chain, as well as pixel reset noise.

MIT Lincoln Laboratory999999-6

XYZ 04/21/23

VRST1 or VRST2

Or DC

Per-column Sample/Hold(S/H)

MIT Lincoln Laboratory999999-7

XYZ 04/21/23

RSTG1 Is ON; RSTG2 Is ON VRST1 = 1.5V (irrelevant) ; VRST2 = 2kHz Sine Wave

None 50kHz 500kHz

ADC Anti-Alias Filter

Caution: Data from 2/19/08. Later I found a software bug which leads to some uncertainty about filter settings. Bug has since been fixed

Sample/Hold FET is always ON – this enables a 65,536 point FFTADC trigger frequency = 25kHz

Here the Pixel is held in RESET and we are sampling a 2kHz Sine Wave Mean~1.5V, Amplitude~500mV

MIT Lincoln Laboratory999999-8

XYZ 04/21/23

RSTG1 Is ON; RSTG2 Is ON ; VRST1 = 1.5V (irrelevant) ; VRST2 = 2kHz Sine Wave FFT of Second Row of Data (256point FFT)

Frequency of input sine wave is correctly extracted by FFTNoise of VRST2 function generator power supply is included

Total noise at output = sqrt(100 µV2/Hz *12.5e3 Hz) = 1118 µVrms

100µV2/Hz

Power Spectrum of Signal Chain from Pixel to output

2kHz

MIT Lincoln Laboratory999999-9

XYZ 04/21/23

RSTG1 Is ON; RSTG2 Is ON ; VRST1 = 1.5V (irrelevant) ; VRST2 = 2kHz Sine Wave

FFT of ALL Data (65536-point FFT)

Row-2 data Row-3 data

Data file is not a continuous stream of 256x256 samplesObserve discontinuity between sequential “rows” of dataThis corrupts FFT

MIT Lincoln Laboratory999999-10

XYZ 04/21/23

RSTG1 Is ON; RSTG2 Is ON VRST1 = 1.5V (irrelevant) ; VRST2 = 2kHz Sine Wave

None 50kHz 500kHz

ADC Anti-Alias Filter

Caution: Data from 2/19/08. Later I found a software bug which leads to some uncertainty about filter settings. Bug has since been fixed

“Column” Sample/Hold asserted once per “Row” – can do a 256 point FFT on a “Column” of dataADC trigger frequency = 25kHz across the row; SH frequency 80.906 Hz down the column

Here the Pixel is held in RESET and we are sampling a 2kHz Sine Wave Mean~1.5V, Amplitude~500mV

MIT Lincoln Laboratory999999-11

XYZ 04/21/23

RSTG1 Is ON; RSTG2 Is ON ; VRST1 = 1.5V (irrelevant) ; VRST2 = 2kHz Sine Wave

FFT of Second Row of Data

Should repeat this at higher sampling freq to extract further into 1/f roll off regime

Total noise at output = sqrt(40 µV2/Hz *12.5e3 Hz) = 707 µVrms

40 µV2/Hz

S/H is asserted once per “Row”Power Spectrum of Signal Chain from S/H to output

MIT Lincoln Laboratory999999-12

XYZ 04/21/23

RSTG1 Is ON; RSTG2 Is ON ; VRST1 = 1.5V (irrelevant) ; VRST2 = 2kHz Sine Wave

FFT of Second Column of Data

Vertical Slice through Slide #10 dataFFT at very low frequency range (S/H frequency is 80.91Hz)Input 2kHz sine wave is down sampled by S/H to ~8HzShould repeat this at higher sampling freq to extract further into 1/f roll off regime

Power Spectrum of Signal Chain from Pixel to output

MIT Lincoln Laboratory999999-13

XYZ 04/21/23

None 50kHz 500kHz

RSTG1 Is ON; RSTG2 Is ON VRST1 = VRST2 = 1.5V DC

ADC Anti-Alias Filter

Caution: Data from 2/19/08. Later I found a software bug which leads to some uncertainty about filter settings. Bug has since been fixed

Here the Pixel is held in RESET and we are sampling the DC Levelgenerated by the National Instruments Analog Output card for

VRST2

“Column” Sample/Hold asserted once per “Row” – can do a 256 point FFT on a “Row” of dataADC trigger frequency = 25kHz

MIT Lincoln Laboratory999999-14

XYZ 04/21/23

RSTG1 Is ON; RSTG2 Is ON ; VRST1 = VRST2 = 1.5V DC FFT of Second Row of Data

Should repeat this at higher sampling freq to extract further into 1/f roll off regime

Total noise at output = sqrt(1 µV2/Hz *12.5e3 Hz) = 112 µVrms

1µV2/Hz

S/H is asserted once per “Row”Power Spectrum of Signal Chain from S/H to output

MIT Lincoln Laboratory999999-15

XYZ 04/21/23

Summary

• FFT algorithm seems to work

• From ADC sample rate of 25kHz, signal chain noise (including National Instruments VRST2 power supply) is 112µVrms [see slide #14]

• A-to-D antialias filter (low pass filter) is doing something, but I’m not sure what, especially because the test conditions got mixed up

– Should try to inject an out-of-band signal to confirm operation of anti-alias filter

• Next:– Exercise RSTG2 pulsing to extract reset noise– Extend operation to faster sampling rates, so as to better observe 1/f roll off

from FFT– Square wave input on VRST2 (monitor output rise/fall time)– Gain/bandwidth curve from single pixel– Cd-109 exposure with this chip