Compact Integrated Receivers Using Custom and Commercial MMIC Technology

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Compact Integrated Receivers UsingCustom and
Commercial MMIC Technology

• Matt Morgan
• 9/7/2006

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Compact Integrated Receivers

• 1. critical for focal plane arrays
• ? beam spacing
• ? field of view
• 2. lower mass
• ? more efficient cryogenics
• ? tighter temperature control
• ? reduced mechanical load
• 3. fewer connectors and cables
• ? greater reliability
• ? reduced VSWR effects
• ? reduced gain slopes
• ? fewer entry points for RFI

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MMIC Modules are More Compact, Lightweightand
Manufacturable than Conventional Assemblies
Assembly of Individually Packaged Components
Multi-Chip Module
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Many MMICs available Commercially

• Most things below 50 GHz are available
  off-the-shelf for less than 50
• Exceptions include
• ? balanced port configurations
• ? non-standard impedance
• ? some wide IF-Band mixers
• Some things in the 50-100 GHz range can be found
  in commercial product
• listings, but
• ? sparse frequency coverage
• ? usually narrow-band, targeted for specific
  applications
• (communication and radar bands, etc.)
• ? some exotic functions not supported (compound
  switches, etc.)
• Finally, there is a large pool of proven custom
  designs to draw from,
• designed by NRAO and our collaborators (JPL, ATA,
  universities,
• foundry IRAD designs, etc.)

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Some Examples W-Band Signal Source
2.5 cm
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Some Examples Compact Water Vapor Radiometer
All Commercial MMICs!
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Some Examples ALMA Active Multiplier Chain
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Some Examples DSN Array Ka-Band Downconverter
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Working Toward an All-MMIC Receiver

• 1. Once a design is set, MMIC components and
  assemblies can be mass-
• produced with exceptional repeatability
• ? especially in the cm-wave range, where most
  MMICs are
• commercially available chips are screened by
  the manufacturer
• and their specs guaranteed.
• ? module assembly is insensitive to small
  variations bondwires are
• used for 50 ? interconnects, not for tuning!
• 2. Repairs are relatively easy to diagnose and
  repair
• ? because of the inherent uniformity in
  performance, device failure is
• usually apparent from the DC bias alone.
• ? when it isn't, the chips are cheap enough to
  simply replace them one
• at a time until the culprit is found.
• It is therefore reasonable to think about
  implementing even very sophisticated
• front-ends in a single module using all MMIC
  technology.
• ? no internal connectors!
• ? no internal cables!
• ? only 1 block to machine
• ? small, lightweight, manufacturable

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Shall we take integration a step
furtherReceiver-on-a-Chip?

• I would say no...
• ? LNAs, mixers, and multipliers have all been
  demonstrated on common
• semiconductor technologies, but with
  compromised performance better
• to pick the right MMIC process for the right
  chip
• ? even if it works, the yield is too low on
  III-V semiconductors for large-scale
• integration
• ? a lot of expensive wafer real estate is wasted
  on passives
• ? can no longer take advantage of commercial
  components have to design
• it all from scratch
• ? no opportunity for chip reuse
• ? Microwave substrates are thin! A large,
  floppy chip would be too hard to
• handle and mount without damaging it.

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Could We Put the Whole Receiver in OneModule and
Cool Everything?

• Not if it is a heterodyne receiver, because
• ? LO generation dissipates too much power for
  cryogenics
• ? IF components are usually Silicon, which will
  not function cold
• However, special-purpose direct detection
  receivers could occupy
• a single cold module
• ? even more compact
• ? better sensitivity
• ? better temperature stability
• ? better component lifetime

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Another Problem Why are those bias boards so
big?

• Because we put a lot on them!
• ? linear regulators
• ? potentiometers for tuning and gain
• control
• ? digital logic for configuration switching
• and channel selection
• ? Op-Amps for gate servo loops and
• monitor points
• ? IF circuitry
• It makes for a user-friendly module, but
• if we're serious about compactness,
• particularly for focal plane arrays, then we
• must find a way to trim this part down.

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Option 1 Develop Common Bias Blocks in Die
Formor Integrated SMT Packages

• Two external resistors
• set the desired drain
• voltage and current.

Probably very expensive! (unless we buy millions
of them) Not suitable for cooling if done in
Silicon.
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Option 2 Limit DC inputs to analog bias voltages

• Put nothing in the block except
• basic EMI and over-voltage
• protection.
• All current control, monitoring,
• and tuning functions can be
• implemented in a central MC
• unit (more efficiently, in fact...)

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Option 2 continued...

• With all monitor functions in one place, some
  parts can be shared.

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What About LNAs?
MMIC LNAs
MIC LNAs
? higher-Q passive components ? allows
pre-selection of active devices for
optimum performance

• ? more compact
• ? easier to integrate in large
• multi-function modules
• ? easy to replicate
• ? module assembly can be
• done commercially

Pros
? difficult to transfer assembly "know-how" to
commercial manufacturers.
? larger development cost
Cons
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A "Nearly Monolithic" LNA
Discrete stage
MMIC stage

• Maybe we can compromise between optimum
  performance and large-scale
• manufacturability by using a hand-picked
  first-stage discrete device followed
• by a MMIC.

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Case Study Ka-Band All-MMIC Receiver

• Calculated Performance
• ? noise temperature 10 K
• ? gain 60 dB
• ? P1dB -45 dBm (input)
• ? LO 2 mW (6-9 GHz)
• ? power dissipation 150 mW (cold part), 3.5 W
  (warm part)

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All-MMIC Cold Receiver Module
IF outputs
IF hybrids
MMICs

• RF inputs

LO input (underneath)
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All-MMIC Cold Receiver Module

• The size of a well-designed MMIC module is
  typically
• dominated by connectors and waveguide flanges.

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MMIC-Based Cold Receiver Assembly
Cooled Focal Plane Array

• OMT

MMIC Module
Bias/MC
IF
LO
IF
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Backup slides follow
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If the entire receiver is cooled anyway, should
we considerusing superconducting passive
elements (couplers, filters, etc)?

• I don't think so
• ? excellent LNA performance can be achieved at
  20K, but a good
• microwave superconductor would force you to
  much lower
• temperatures (5K)
• ? not really a commercial process your passive
  elements
• could be more expensive than the MMICs!
• ? you lose the ability to test it at room
  temperature
• ? not much to gain anyway? superconductors are
  not lossless
• at high frequency, and cooled copper may be
  competitive if it is
• reasonably pure