1. MEDA Wind Sensor Front End ASIC S. Espejo, J. Ceballos-Cáceres, A
MEDA Wind Sensor Front End ASIC S. Espejo, J. Ceballos-Cáceres, A. Ragel-Morales, S. Sordo-Ibáñez, L. Carranza-González, J.M. Mora-Gutiérrez, M.A. Lagos-Florido, J. Ramos-Martos IMSE-CNM (CSIC/Universidad de Sevilla) Parque Científico y Tecnológico Cartuja, Calle Américo Vespucio s/n, 41092, Sevilla, SPAIN mailto:
AMICSA 2016, June 2016, Gothenburg, Sweden

2. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
MEDA Instruments for Mars 2020
The MEDA Wind Sensor
The MEDA WS Front-End ASIC
Circuitry description
Experimental results (example)
Summary

3. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
NASA’s/JPL’s Mars 2020 Mission
Images taken from & further details at:

4. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
MEDA: Mars Environmental Dynamics Analyzer
A set of sensors that will provide measurements of:
Temperature
Wind speed & direction
Pressure
Relative humidity
Dust size & shape
Principal Investigator: José Antonio Rodríguez-Manfredi Centro de Astrobiología, Instituto Nacional de Técnica Aeroespacial, Spain
Further details at:

5. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
MEDA Wind-Sensor Concept
Developed at Polytechnic University of Catalonia (*1)
Evolved version of a similar sensor used in REMs (*2)
(*1) M. Domínguez, V. Jiménez, J. Ricart, L. Kowalski, J. Torres, S. Navarro, J. Romeral, and L. Castañer, “A hot film anemometer for the martian atmosphere,” Planetary and Space Science, vol. 56, pp – 1179, June 2008
(*2)

6. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
The MEDA WS FE ASIC: PARTICIPANTS
CAB:
MEDA Instruments coordination
Polytechnic University of Catalonia:
Wind sensor concept
ASIC Specification
CRISA:
ASIC specification
Design-process quality control
High-level digital code of the control and communications FSM
IMSE-CNM-CSIC:
Analogue architecture and blocks
RH Digital lybrary
Synthesis and back-end of the digital part
ASIC design and verification, RH techniques

7. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
The MEDA WS FE ASIC: Process Technology & Previous work
Standard 0.35mm CMOS technology, from AMS (Austria Micro Systems)
Only 3.3V transistors used along the chip
Builds on previous efforts by the authors in the past years:
Characterization of radiation and low-temperature effects on devices in this technology
Development and validation of a rad-hard library of digital cells
Previous development of several other mixed-signal space ASICs

8. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
The MEDA Wind-Sensor Front-End ASIC (I)
Must measure various temperatures
Temp measurements based on external Pt resistors
Must provide bias current
Must measure and digitalize voltages
Must control the temperature of external “hot-dies”, keeping it constant at prescribed values
Must provide and measure the heating power required to do so
Must interact and communicate with the Instruments Control Unit (ICU)

9. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
The MEDA Wind-Sensor Front-End ASIC (II)
AD CONVERSION CHANNEL
DIGITAL CONTROL BLOCK
THERMAL CONTROL LOOPs
ICU
SCAN PATH
GATOs GDTOs
Residual POWER SINKS
EXTERNAL DIES: HEATERS & TEMP SENSORS
EXTERNAL RESET & POR OBSERVATION
V & I References
EXTERNAL LTC RESISTOR & VREF MEASUREMENT
SIGNAL CONDITIONING
Band Gap
ASIC Temp Alarm
WS Temp Alarm
POR
RS-422 R&Ts (Clock & data)
MUXES
External SENSORS
MUXES (4-wire interfaces)
Internal Signals
clock
commands & data
ASIC Temp
Calibration Levels
Programmed External Dies Temps (DACs)
data
VDD/3
POWER (HEAT) (variable)
Dies Temp: sensor bias & signals
POWER (residual)
data (power counts)
Voltage & Current references for all circuit blocks
(Self-Biased)
Miscell. internal signals
(test and diagnosis)
Block containing Configuration Register(s)
Control signals
Programming buses (address & data)

10. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
The MEDA Wind-Sensor Front-End ASIC (III)
Die size: 5 x 5 mm

11. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
External Interface (Pins)
Communication (Rx & Tx) and clock (6 pins)
RS-422 differential signals
Rx (2), Tx (2), Clk 2.4MHz (2)
External analog input channels (18 pins)
9 differential external input channels
Thermal control loops (36 pins)
12 thermal control loops
Each: Current bias and Temp measurement (1), heating current (1), and current sink (1)
Power and Ground (29 pins)
6 power domains. Non-paired VDD/GND distribution
Miscellaneous uses (11 pins)
Vref (1), Iref (1), Rst (1), Scan-path (4), Observability (2+2)
Total: 100 pins. Package: CQFP-100

12. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
The ADC channel
The input channels multiplexer
Bias current/voltage for input signals and sensors
Preamplifier
ADC-FSM
Oscillator
Analogue integrator
Comparator
Reference signal
ADC channel calibration

13. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
The ADC channel
gain
level-shift
integrator control
VCM-ref
VREF (level-shift)
comparator control
PREAMP-1
PREAMP-2
INTEGRATOR
COMPARATOR
VREF (ADC)
INP
INN
Zero- Crossed
OSCILLATOR
(50 MHz)
ADC-FSM
start
eoc
data-out
From DIGITAL CONTROL BLOCK
To/From DIGITAL CONTROL BLOCK
From BONDING PADS & INTERNAL SIGNALS
From VOLTAGES REFERENCE BLOCK
Programmable from 0 to 750mA, 4 bits

14. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
The ADC channel

15. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
The Instrumentation Amplifier

16. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
The ADC itself

17. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
The Comparator
Fast clock (~50MHz)

18. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
The Oscillator
Same R-type and same C-type than those used in the integrator

19. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
Reference voltage:
From band-gap and scaling amplifier
Set of DC input levels used for real time on-line calibration:
Offset error
Gain error

20. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
The Thermal Control Loops
The bias current sources
The comparator
The heating current sources
The DACs
ASIC
Hot Die

21. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
The Thermal Control Loops
Clocked Switched-Capacitor comparators
Auto-zero
Regenerative Latch
Very low offset (< 0.1mV)
Resistive string DAC

22. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
The Communication & Digital Control Unit (FSM)
Receives and executes commands, and sends data to/from the instrument control unit (ICU).
Communicates through an UART at 9600 bauds. RS-422 differential signals.
Reads and writes configuration and data registers.
Controls the operation of the thermal control loops (comparators, heating currents, counts additional heating current pulses to each hot die).
Controls the AD conversion channel, and the sequence of conversion of the 20 channels that are time-multiplexed, according to various operating modes.
Receives the alert signals from the over-temperature sensors corresponding to the hot-dies and the ASIC itself, and takes the corresponding actions when required.
Enables and disables different circuit blocks in the ASIC.
Receives parity checks from the registers in the ASIC, and reports to the ICU in case of errors.
Works in various operating modes: cyclic mode, on-request mode, test-mode, …
Includes a scan-path port for testability purposes.
High-level design by CRISA.

23. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
Auxiliary Blocks
Band Gap and Voltage Reference
PTAT
Current Reference
High-Temp Alarms & Auto Shut Down.
Power-on Reset
Power Supply Voltage measurement
RS-422 Receivers and Transmitter
Reference levels for ADC calibration

24. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
RHBD Techniques and Low-Temp issues (I)
Known techniques available in the literature
Builds on previous work by the authors in the characterization of radiation and low temperature effects on this specific CMOS technology [7],[8].
Analogue circuitry: full-custom, enclosed-layout transistors (ELTs) for nmos, regular layout for pmos (TID)
Guard-rings around nmos and pmos devices (SEEs).
Specific type of converter, size of capacitors (SET).
Role of the ASIC: allows sporadic wrong behaviour.
Similar mixed-signal ASICs designed and tested using the same procedures in the same technology have been shown to be latch-up free up to at least 80 MeV·cm2/mg. Same result is expected.
Digital sections: semi-custom. RHBD digital cells library developed. Same RHBD techniques than in analogue circuitry.
All registers in the ASIC include parity-check. Parity errors are reported to the digital control unit, which in turn reports this events to the ICU.

25. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
RHBD Techniques and Low-Temp issues (II)
The ASIC is specified to operate within -128 ºC to 50 ºC, ambient temperature.
Electrical simulations: foundry provided models are not qualified below -55ºC.
The authors have measured transistors I-V characteristics down to -110ºC and verified that the transistor models can be used with reasonable accuracy down to this limit.
The actual temperature operation range of the die will be quite above the ambient-temperature operation range, due to self heating (low density of Mars atmosphere)
Specific radiation (TID & SEE) and low temperature tests in a "Mars Chamber", are planned for the coming months.

26. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
Experimental Results
Communication and Control functions: operative
The ADC channel: operative, within specs
Thermal Control loops: operative, within specs
Miscellaneous functions: operative, within specs
Specific set of boards
Raspberry Pi for communications
Sample hot dies from UPC

27. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
ADC Channel

28. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
Thermal Control Loops

29. MEDA Wind-Sensor Front-End ASIC, AMICSA 2016
Summary
A rad-hard, mixed-signal ASIC in a standard 0.35 mm CMOS technology has been designed, fabricated and functionally tested.
The ASIC is an analogue front-end for the MEDA wind sensor for NASA's Mars2020 mission
Additional radiation and low temperature measurements are underway. Expected to be satisfactory based on previous ASICs designed in the same technology using the same RHBD techniques and the same rad-hard digital library.