Stefania Chicca – Aurelia Microelettronica Franco Bigongiari – Aurelia Microelettronica

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AMICSA 2008: REMS ASICAMICSA 2008: REMS ASIC

11

Stefania Chicca – Aurelia MicroelettronicaFranco Bigongiari – Aurelia MicroelettronicaJesus Lopez Soto – EADS Astrium CrisaCascais, Portugal 2Cascais, Portugal 2ndnd September 2008 September 2008

Mixed-Signal ASIC for Rover Environmental Mixed-Signal ASIC for Rover Environmental Monitoring SystemMonitoring System



22

PRESENTATION CONTENTSRover Environmental Monitoring System

• REMS ASIC Presentation• REMS ASIC Functional Overview• ASIC Analog interface• Internal Analog to Digital Converter• Test Activity: temperature tests and comments on test

results• Qualification activity: actual status and qualification

flow



33

REMS ASICMMars Mission in 2009 funded by NASA/Spanish GovernmentTTo investigate the past and present habitability at the surface of MarsAAurelia is subcontractor of CRISA-EADS Astrium

Front-end ASIC for wind, Front-end ASIC for wind, temperature and temperature and humidity sensorshumidity sensors



44

REMS ASIC GENERAL BLOCK DIAGRAMREMS ASIC GENERAL BLOCK DIAGRAM

RS422

M U X

RS422

DATA &

CONF

UART ANALOG FRONT END

ON CHIP CALIBRATION

MUX & ADC

MIXED MODE FRONT END (WIND SENSORS) D DATA

REGISTER

feedback

anti alias & ADC



55

REMS ASIC building blocksREMS ASIC building blocks• 12 PC sigma-delta channels to interface with wind sensors• 3 channels to measure the threshold temperature of sigma delta

channels• 4 channels to amplify the thermopile signals • 1 channel to amplify the air temperature sensor signal• 1 channel to measure the temperature for thermopile calibration

purposes• 1 channel to heat two of the thermopile sensors• 7 channels to amplify the temperature PT signals• 1 external channel• Power on reset generator• Voltage reference circuit• Bias section to provide current bias to the sensors and to the internal

circuitry• 16 bit sigma delta A/D converter • Clock receiver on RS-422 Physical Layer and internal clock divider• Logic Control Unit, Configuration Registers, Output Data Registers• UART with RS-422 transmitter/receiver



66

REMS ASIC Block Diagram & InterfaceREMS ASIC Block Diagram & Interface

clock receiver & generator

dividers

UART IN reg

UART OUT reg

UART & INTERNALCFG & OUTREGISTERS

UART

clk 1.15MHz

toADCMUX

Low gain Amp X ( " 2L_Temp" ) Channel to ADC

+

-40 max,

80mA

Power Current Generator X 1 Channel

Bandgap&

Ref Followers

VCM VHVL

VCM

Reference Biaswith external

resistor

bias [n] Power On Reset

BIAS

MOD

MUX

VC

MV

HV

L

to UART

Analog_IN_OUT+

High Gain Low Noise IR_COND X 4 Channels

ADC

Thermo_Heater+

V_1V

V_1V

IR_COND_n_Sensing+

IR_COND_n_Sensing-

Ref_BIAS

Rtemp_n_Sensing+

Rtemp_n_Sensing-

TX+N

TX-N

RX+N

RX-N

CLK+N

CLK-N

LNPG

A

toMUX

CFG 3 bitfromUART

IR_COND_n_Filtering

17 diff. channels

clk 1.15MHz

resetsignal

to

UART

+

-

AVDD DVDD AGND DGND Analog_IN_OUT-

MUX

MUX

toMUX

V_1V

+

-

IR_CAL" and "Air Temperature" Channels to ADC

Thermo_Cal_Sensing+(Air_Temp_Sensing+)

Thermo_Cal_Sensing-(Air_Temp_Sensing-)

compD

CK

Q

sense X 12 Channels

LATCH_COMP

toUART

power force X 12 Channels

sensor bias X (12 + 3 REF) Channels

CFG 7 bitfrom UART

toMUX

Low Gain Sensor Amp X 3 Channels to ADC

MU

X n

to 1

bias [n]

WD_Rx_IN_nn=0..11WD_Ref_IN_nn=0,1,2

WD_Ref_RTN_nn=0,1,2

WD_Heater_OUT_nn=0..11

WD_Rref_Sensing+_nWD_Rref_Sensing-_nn=0,1,2

Inx Imx

auto zeroedpre-amplifier

internal analogground, 1V

duty cyclelimiter

biasinginterval

modulatorDUTY

RSW OR ADCacquisition

ampREF_OUT

WD_Totalcounter

WD_OUTcounter

controlsfrom

UART

controlsfromUART

+

-

to GND



77

REMS ASICREMS ASIC



88

REMS ASIC ENVIRONMENT & TECHNOLOGYREMS ASIC ENVIRONMENT & TECHNOLOGYThe REMS ASIC has been designed for a storing temperature ranging from –135°C to +125°C and an operating temperature ranging from –55°C to 90°C

The ASIC will be warmed up to the minimum operating temperature by an external heater prior to power up

Latch up immunity is provided by XFAB 1.0um CMOS SOI-HV technology

TID level requirement of 7Krad(Si) is not a concern for the selected technology: irradiation tests operated in the frame of other activities showed applicability up to 50Krad

Single event upset mitigation is performed inside the digital section to avoid loss of functionality

ASIC die size: 62.8 mm2

Assembled in CQFP100 package



99

REMS ASIC SENSOR INTERFACEREMS ASIC SENSOR INTERFACERTemp interface: 7 Pt 1000 sensors are interfaced by the ASIC: internal controlled-current biasing is supplied to the sensor only during signal acquisition to limit self-heating: an internal multiplexer multiplexes the channels to the internal ADC and the biasing current to the sensor which is being acquired

Air_Temp interface: 1 Pt 1000 sensor for measuring the Mars atmosphere temperature and 1 Pt 1000 sensor for measuring the infrared radiation source to calibrate the infrared temperature sensors

Thermopile interface: 3 infrared sensors, whose conditioning chain inside the ASIC offers several programmable gains up to 2048

Therm_heater interface: an heater circuit able to provide up to 100mA is integrated into the ASIC to calibrate in flight the infrared sensors R_therm_cal interface: it is organized to bias and measure a PT 1000 resistor and it is used for calibration purposes

WD_CON wind interface: 3 wind transducers treated inside the ASIC as sigma-delta channels



1010

• 3 groups, 4 sensors each

• each sensor is treated by a SD, that drives (with a current Inx) an external heater (Rheater) to keep Rx-sensor temperature at a given value (fixed by Rref, 1Rref/group)

• bias currents for Rx and Rref are multiple of an unique current reference

• internal adjusting on Rref bias current is provided in 64 steps

• the drops on the 3 Rref resistors are amplified and converted by the ADC

• all the heaters are activated in parallel

• force and sense pins on Rref are separated

WD_COND SENSORS CHANNELSWD_COND SENSORS CHANNELS

compD

CK

Q

sense X 12 Channels

CK1

toUART

power force X 12 Channels

REF_BIAS

sensor bias X (12 +1REF) Channels

CFG 6 bitfrom UART

toMUX

Low Gain Sensor Amp X 3 Channels to ADC

MU

X n

to 1

bias [n]

WD_Rx_IN_nn=0..11

WD_Ref_IN_nn=0,1,2

WD_Ref_RTN_nn=0,1,2

WD_Heater_RTN_nn=0,1,2

WD_Heater_OUT_nn=0..1

WD_Rref_Sensing+_nWD_Rref_Sensing-_nn=0,1,2

Inx Imx

auto zeroedpre-amplifier

internal analogground, 2.5V

duty cyclelimiter

biasinginterval

modulatorDUTY

RSW

ampREF_OUT

WD_Totalcounter

WD_OUTcounter

toUART

controls fromUART

controls fromUART



1111

+

-

-

+

C

C

IA

V25

V25

V25 V25

V25

V25

+

-

-

+

+

+

-

-

Track & HoldIII stage:programmable gain256, 500, 2000 byacting on capacitorratio

I stage:programmable gain 8to 128 by acting onfeedback DAC

II stage:only used for offsetcancellation purposes

internally connectedto 2.5V

IR_COND Thermopile channelsIR_COND Thermopile channels



1212

Pt, Air_temp, IR_CAL, REF_Amp ChannelsPt, Air_temp, IR_CAL, REF_Amp Channels

R_TEMP_N_Sensing+

R_TEMP_N_Sensing-

amp

+

-

+

-

buffer

analog ground 2

analog ground 1

+

+-

-

10K

AVDD

Temperature

active onlyduring ADCacquisition

to ADC

Single-ended to differential conversion (with 2.5V common mode)common mode range: analog_ground 1 = 1V analog_ground 2 = 1.5V



1313

REMS ASIC DIGITAL SECTIONREMS ASIC DIGITAL SECTIONThe digital section contains:

RS422 receiver RS422 Transmitter Control Unit

The control unit decodes the command and prepares the answer, manages the acquisition from wind sensor channels and stores the data coming from ADC.



1414

REMS ASIC DIGITAL SECTIONREMS ASIC DIGITAL SECTION

RX ShiftRegisters

andControl

TX ShiftRegisters

andControl

Data-RX

Data-TX

CommandsDecoder

andHandling

Unit

Configuration Registers Output

Reset Request Output

DataHandling

UnitConverted Analogue Data

(16 bits)

Com

man

d Ec

ho

Ana

logu

e D

ata

Dum

p En

able

Win

d Se

nsor

Dat

aD

ump

Enab

le CONTROLUNIT

UART

Countersfor 12 Wind

SensorChannels

From 12 WindSensor

Comparators

ADC MUX Selector (5 bits)

RSW and Duty



1515

REMS ASIC A/D CONVERSIONREMS ASIC A/D CONVERSION

Internal Analog to Digital II order sigma-delta converter is integrated with programmable conversion time: the converter provides an analog anti-aliasing active filter before conversion and a digital filter on converted samples after decimation down to 400Hz cutoff frequency: the noise filtering is achieved internally to the ASIC in this way (no need for software-processing the converted data).

z-1

1-z-1

z-1

1-z-11/4

1/4

1/3

Fig. ‑1: ADC z-domain representation

X Y

II order sigma delta ADC

Decimation filter



1616

REMS ASIC TEST ACTIVITYREMS ASIC TEST ACTIVITY

A dedicated test setup has been developed in Labview environment to allow automatic testing.

On the right, the output for an infrared channel as a function of the input voltage is shown: however, relevant parameters are downloaded directly into datalog files.



1717

REMS ASIC TEST RESULTS: INFRARED REMS ASIC TEST RESULTS: INFRARED CHANNELSCHANNELS

• Repeatability of parameters on different samples

• Gain accuracy: 512,256,128,64,32 and 16 <2.5%. 2048: max 3% 8: max 2.8%

• The output range of the channels is a valid value for the input ADC input range in all cases but one, (2048 3.5V, some saturation occurs at full scale).



1818

REMS ASIC TEST RESULTS: Pt 1000 REMS ASIC TEST RESULTS: Pt 1000 channelschannels

• Electrical test emulates sensor resistance variation with temperature by means of a 16 bit DAC-provided voltage



1919

REMS ASIC TEST RESULTS: Pt 1000 REMS ASIC TEST RESULTS: Pt 1000 channelschannels

Gain Variation versus Temperature

3,5

3,8

-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90

Temperature °C

gain

R0 Air_temp R_therm

R0 T=90°C T=25°C T=0°C T=-20°C T=-40°CGain 3,5858 3,5772 3,6004 3,5872 3,5895Offset -3,6501 -3,5963 -3,5895 -3,5474 -3,5058INL 1,32 4,02 3,33 1,47 2,1Air_temp T=90°C T=25°C T=0°C T=-20°C T=-40°CGain 3,5935 3,599 3,598 3,6044 3,5948Offset -3,875 -3,85226 -3,8228 -3,7968 -3,7425INL 1,55 1,8 1,75 1,83 2,33R_therm T=90°C T=25°C T=0°C T=-20°C T=-40°CGain 3,5962 3,6018 3,5963 3,5916 3,595Offset -3,8806 -3,8549 -3,8198 -3,7842 -3,7418INL 1,01 6,15 1,77 3,02 2,19

Gain and offset deviation over temperature

R0 T=25°C vs T=-40°C T=25°C vs T=90°CGain Deviation -0,34% -0,24%Offset Deviation 2,52% -1,50%Air_temp T=25°C vs T=-40°C T=25°C vs T=90°CGain Deviation 0,12% 0,15%Offset Deviation 2,85% -0,59%R_therm T=25°C vs T=-40°C T=25°C vs T=90°CGain Deviation 0,19% 0,16%Offset Deviation 2,93% -0,67%



2020

BIAS SECTION: CURRENTS STABILITY & MATCHINGBIAS SECTION: CURRENTS STABILITY & MATCHINGIx Current Ix Full Scale Ix Zero Scale IREF Ix Current Ix Full Scale Ix Zero Scale IREF Ix Current Ix Full Scale Ix Zero Scale IREF

CH 0 99,7 95,7 104,1 98 98,7 94,5 102,5 96,6 100 96,9 104,4 97,8CH 1 100,1 96,1 103,7 98 98,8 94,5 102,5 96,6 100,8 97,8 104,6 97,8CH 2 99,6 96,4 103,9 97,5 98,9 94,6 102,4 97,2 99,6 95,5 104,2 98CH 3 100,3 95,97 104,4 97,5 98,8 95,1 102,2 97,2 100,6 96 103,9 98CH 4 100,1 96,05 104,8 97,5 99,6 93,8 101,8 97,2 99,4 95,9 103,8 98CH 5 100,4 96,6 104,2 97,5 99,3 95,7 103,2 97,2 100,5 97 104 98CH 6 99,6 95,6 103,5 98 98,3 94,6 102 96,6 100,2 96,2 103,7 97,8CH 7 99,4 95,38 103,6 98 99,3 95 101,8 96,6 99,3 95,5 103,5 97,8CH 8 99,6 95,43 103,6 97,3 98,6 93,6 102,1 96,8 101,1 97,1 104 97,9CH 9 99,6 94,88 103,5 97,3 98,9 94,6 102,1 96,8 99,7 96,1 103,7 97,9CH 10 100,7 97,23 104,3 97,3 98,6 94,7 102 96,8 100,1 96,4 103,9 97,9CH 11 100,3 96,08 103,9 97,3 98,7 94 102,8 96,8 99,6 94,9 103,4 97,9

Input Currents (VDD=5V)

T Room T=-55°C T=90°C

Ix (bias) versus channel number

98

98,5

99

99,5

100

100,5

101

101,5

0 1 2 3 4 5 6 7 8 9 10 11 channels

Ix C

urre

nt (u

A)

T RoomT=-55°CT=90°C



2121

SCREENING FLOWSCREENING FLOWThe screening has been performed on 210 parts according to requirements NASA GSFC EEE-INST-002



2222

SCREENING FLOWSCREENING FLOW



2323

SCREENING FLOWSCREENING FLOW Big effort has been put to find a glue for die attach

able to survive at –135°C

30 parts have been selected after screening and an extra electrical characterization has been performed (the measurements have been repeated between –55°C and 90°C with 10°C step).

On the 10 parts out of 30 have been performed further electrical test between –55°C to –135°C to verify the possibility to work at temperature near to mars atmosphere.

Only one part doesn’t work down to –65°C6 parts work correctly down to –135°C but the

parameters are out of specification3 parts work correctly down to –135°C with the

expected parameters



2424

QUALIFICATION FLOWQUALIFICATION FLOW



2525

QUALIFICATION FLOWQUALIFICATION FLOW

REMS ASIC is classified as SCD Level 2 (Source-Vendor Control Drawing) according to EEE-INST-002 Section M3, Microcircuits, Monolithic: as a consequence, the qualification flow included in EEE-INST-002 is followed(to allow screening according to the reliability standard MIL-PRF-38535, Class Q, QML-38535).



2626

THERMAL CYCLING PLANTHERMAL CYCLING PLAN



2727

QUALIFICATION ACTIVITY: THERMAL CYCLESQUALIFICATION ACTIVITY: THERMAL CYCLESD2009 (REF NO CYCLES) D2003 (6200 CYCLES) D2004 (6200 CYCLES) D2006 (6200 CYCLES) D2008 (6000 CYCLES)

115 110 125 120 105-1,653 -1,778 -1,660 -1,583 -1,637-1,730 -1,716 -1,654 -1,728 -1,641-1,648 -1,567 -1,647 -1,687 -1,594-1,719 -1,567 -1,758 -1,699 -1,664-1,689 -1,652 -1,573 -1,653 -1,665-1,645 -1,669 -1,607 -1,796 -1,666-1,706 -1,575 -1,608 -1,709 -1,562-1,731 -1,586 -1,678 -1,665 -1,772-1,668 -1,784 -1,708 -1,727 -1,60565,077 67,430 66,689 66,023 69,38265,371 61,925 65,113 68,641 63,71264,804 62,936 68,706 65,895 62,53166,189 66,405 65,943 66,617 66,053-1,614 -1,644 -1,685 -1,687 -1,683

OK OK OK OK OK

120 110 125 120 115

6000 cycles The ICC is constant during

the test, NO heating effect is

observed The gain are linear and NO

changes of slope are observed

Reference Sample No cycling

The ICC is constant during the test, NO

heating effect is observed The gain are linear and

NO changes of slope are observed

6200 cycles The ICC is constant during

the test, NO heating effect is

observed Some gain are not linear and There are changes of

slope.

6200 cycles The ICC is increase lightly

during the test, A little heating effect is

observed The gain are linear and

some changes of slope are observed

6200 cycles The ICC is increase lightly

during the test, A little heating effect is

observed The gain are linear and

some changes of slope are observed



2828

CONCLUSIONCONCLUSION

A mixed-signal ASIC for signal acquisition and data conditioning has been presented

The ASIC will be used in a meteorological package, to be integrated in the Mars Science Laboratory Rover payload, for being launched on 2009.

The general architecture of ASIC has been presented and some blocks have deeply discussed

A summary of screening and qualification flow have been shown.

Stefania Chicca – Aurelia Microelettronica Franco Bigongiari – Aurelia Microelettronica

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