1 Dec 2012 1

SPP-Fields Antenna Electronics Board (AEB)

Concept Status Report

J.W.Bonnell, S. Harris, S. Heavner

Space Sciences Laboratory

UC Berkeley

(as presented by W. Rachelson)

jbonnell@ssl.berkeley.edu

sharris@ssl.berkeley.edu

selda@ssl.berkeley.edu

1 Dec 2012 2

Summary

• Full time engineering support now available (Heavner), with part-time Science (Bonnell) and Systems (Harris) support as well for the AEB effort, so design progress is being made.

• Close collaboration with PA design effort (Seitz, Bonnell, Goetz) to keep relevant interfaces (power, signal, noise) consistent.

• Specification of breadboard (BB) AEB complete (1 channel – FGND, BIAS, STUB, SUN_SHIELD, +/- 100-V fixed, +/- 15-V floater).

• AEB BB Design in progress (through Dec 2012):– Parts selection (switching supply drivers, DACs, bias output section

transistors)– Schematic and bill of materials (BB and parallel 3DPlus packaging

effort)

Action Time Frame

AEB BB Specification and Design Through Dec 2012

AEB BB Proc, Fab, and Assy Jan 2013 - Apr 2013

AEB BB Electrical Test and INT (LF-PA) Apr 2013 – May 2013

AEB ETU Design, Proc, Fab, Assy, and Test Jun 2013 – Jan 2014

Fields I-PDR Late Oct 2013

Fields ETU INT Feb 2014 – Apr 2014

1 Dec 2012 3

Scope of AEB Design Effort

• Antenna Electronics Board (AEB, see following block diagram slide)– FGND Driver:

• 1 channel each for 4 forward whips.• 1 channel for aft whip or dipole (TBR).

– Sensor bias current, Stub and Shield bias voltage drivers:• 4 channels of each for 4 forward whips.• 1 channel of TBD subset for aft whip or dipole.

– Whip preamp bias range relay control:• 1 channel each for 4 forward whips.• TBD channel for aft whip or dipole.

– Floating and HV output stage Power Supplies:• 2 floaters to support opposing pairs of forward whips.• 1 floater (TBR) to support aft whip or dipole.• 1 HV (+/- 100-V) supply to support FGND and bias driver output stages.

– Serial Command and Data (HSK) I/F to ICU.• Preamp-to-AEB Harnessing (TBR).• AEB-to-DFB Harnessing in MEB (TBR).

1 Dec 2012

AEB – Block Diagram

AEB-4

Replace with simple serial interface to ICU. CAL deleted.

Floaters (1/axis) and HV NOT part of estimate for proposed AEB (assumed part of LNPS).

Possible Channel 5 to support 3rd axis/tail sensor.

1 Dec 2012

AEB – Power Service Concept

AEB-5

• AEB uses existing switching supply designs (THEMIS, RBSP).

• There will be changes to magnetics to accommodate changes in driver frequencies and SYNC requirements.

• AEB takes regulated, filtered supplies from LNPS and providing following supplies:• ± 100-V supply (bias output

stages).• ± 12-V analog (AEB input stages).• ± 15-V floaters (LF-PA supplies).

1 Dec 2012 6

AEB Requirements (Dec 2012)

• Preamp signal characteristics– DC voltage level: ± 60Vdc w.r.t. AGND (THEMIS-EFI-BEB)– AC voltage level: ± 10V w.r.t. floating ground (± 13V capability; RBSP-

EFW-PRE)• Floating Ground Driver

– Input: LF Preamp signal– Input filter roll off: 500 Hz (TBR; RBSP-EFW-BEB)– Output voltage level: ± 60Vdc w.r.t. AGND– Floating supply rails: ± 15Vdc (RBSP-EFW-BEB, -PRE)

• Bias, Stub, Shield Drivers– Reference Input: LF Preamp signal– Reference input filter roll off: 500 Hz (TBR; RBSP-EFW-BEB, match

FGND)– Output voltage level: Vref ± 40Vdc (max, programmable) w.r.t. AGND– DAC resolution: 16-bit (TBR; RBSP-EFW-BEB, THEMIS-EFI-BEB)

• Max voltage required: ±100V (THEMIS-EFI-BEB and IDPU-LVPS)

• Noise voltages at Bias, Stub, and Shield outputs consistent with noise floor requirements and predicted coupling to antenna (TBD).

1 Dec 2012 7

Challenges and Plan for AEB Design Effort

• Adapting existing THEMIS (BEB, LVPS) and RBSP-EFW (PRE) designs for SPP environments, resources, and requirements (all Phase B):– Equally challenging radiation environment than THEMIS or RBSP, but

less mass resources available for shielding:• Compile initial BOM, review against TID and SEE, and re-select parts as

needed.– More functionality (bias control AND power supply) to pack into same

or smaller PWB area, mass and power allocation than THEMIS, RBSP (and MEL values!):

• Prepare initial layout using elements of existing designs to prove fit to PWA area.

• Determine realistic mass and power estimates from elements of existing designs to refine mass and power impact of design options (e.g. 3rd axis measurement).

• Consider and evaluate alternate part types (e.g. SMD rather than through-hole 100-V transistors) to trade change in design against mass/power/thermal benefits.

• Demonstrating DC-LF compatability with MF and HF noise floor requirements:– HF noise floor requirements are one or two orders of magnitude more

strict than THEMIS or RBSP:• Build breadboard channel, including floater and HV supplies using existing

flight spare parts/hardware to allow for noise generation/succeptability testing and prove concept design will meet noise floor requirements at antenna (Phase B/early Phase CD).

1 Dec 2012 8

BACKUP SLIDES

1 Dec 2012

AEB – Mass Estimates (June 2012)

AEB-9

MASS

PWAMass [kg] BOE

Num Channels or Supplies

Mass/Channel[kg/channel] Comments

RBSP-EFW-BEB 0.537 RBSP_EFW_SYS03AB (Mass Budget, FM1) 6 0.0895 1 channel = FGND Drive, BIAS, STUB, GUARD.

RBSP-EFW-LVPS 0.830 RBSP_EFW_SYS03AB (Mass Budget, FM1) 8 0.103751 channel = 1 transformer and supporting switching supply.

Revised Mass CBE

[kg]SPP-FIELDS-AEB (Option 1: 2-axis, 4 bias and FGND channels, 2 floaters, 1 HV) 0.669 4*BEB channels, 3*LVPS channelsSPP-FIELDS-AEB (Option 2: 3-axis, 5 bias and FGND channels, 3 floaters, 1 HV) 0.863 5*BEB channels, 4*LVPS channels

MEL Mass CBE[kg] Contingency

Total w/ Contingency

[kg]

SPP-FIELDS-MEL (120607) 0.362 25% 0.4525

• Floating and HV supply mass impact significant – minimum two-axis system is almost twice the mass carried in the proposal MEL!

• Mass estimate needs to be refined with reference to THEMIS 100-V system, rather than RBSP-EFW 225-V system based on design decisions from June 2012.

1 Dec 2012

AEB – Power Estimates (June 2012)

AEB-10

POWER

PWAPower

[W] BOEPower/channel

[W/channel] CommentsRBSP-EFW-BEB 1.965 RBSP-EFW I-CDR (Sept 2009) 6 0.3275 1 channel = FGND Drive, BIAS, STUB, GUARD.

Revised Power CBE

[kg]SPP-FIELDS-AEB (Option 1: 2-axis, 4 bias and FGND channels, 2 floaters, 1 HV) 1.3 4*BEB channels, nothing for LVPS elements.SPP-FIELDS-AEB (Option 2: 3-axis, 5 bias and FGND channels, 3 floaters, 1 HV) 1.6 5*BEB channels, nothing for LVPS elements.

MEL Power CBE

[kg] Contingency

Total MEL Power w/Contingency

[W]

SPP-FIELDS-MEL (120607) 1.000 25% 1.25

• BEB power consumption can be significant.• Power estimate needs to be refined with reference to THEMIS 100-V system, rather than

RBSP-EFW 225-V system based on design decisions from June 2012.