Test Challenges in MMICs, RFICs and High Speed Analog Circuits

Dror Regev

Dror Regev

Agenda

• Presto-Engineering

• Challenges in Wide-Band and mm-Wave Test

• MMIC/RFIC Probing at high mm-Wave Frequencies

• Standard Automatic Tester limitations

• mm-Wave DUT docking & interfacing challenges

• Solution Approaches & RFIC Test Economics

• Frequency conversion technical consideration example

Dror Regev

Challenges in Wide-Band and mm-Wave Test

Ever growing demand for Data Rate, drive extended BW and Freq.

Wide Band multi-carrier modulation schemes requiring high EVM.

Reduced Dynamic Range, impairments worsen.

5 GHz 60 GHz E-Band

802.11ac Wi-Fi

802.11ad Wi-Gig

PTP 4G/LTE 1.8 GHz 1

60

M

Hz 500

MHz

𝑻𝒉𝒆𝒓𝒎𝒂𝒍 𝑭𝒍𝒐𝒐𝒓 ↑, 𝑵𝑭 ↑, 𝑻𝑿 𝑷𝒐𝒘𝒆𝒓 ↓, Linearity ↓, Phase Noise ↑, Ripple & Reflections ↑

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MMIC/RFIC Probing @ mm-Wave Frequencies

• GSG probe is dispersive and radiates energy

• For good S-par calibration, 30dB isolation

between probes is required. At 150um pitch, calibration

substrate BW is not guaranteed beyond 65-70GHz but perform

reasonably up to E-band frequencies.

• λ/20 GSG Probe pitch, should be maximum pitch for accurate testing. Hence 150um pitch for εr=1 can perform to ~ 100GHz. However, DUT εr will affect test accuracy as :

• 43um GSG probe is needed for best performance at ~ 110GHz.

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MMIC PA Probing @ E-band (71-86GHz)

• CW Gain and Saturation test @ Wafer Level

• 50um Thick GaAs wafer on insulator carrier pose Thermal Stress -> Pulse?

• Recent market drive towards full S-par test.

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RFIC Transceiver Probing @ E-band (71-86GHz)

• 500MHz BW wafer level RX & TX EVM tests • Employing WB Frequency Converters to/from E-band

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Standard Automatic Tester limitations

• Max I/O frequency limited to 6

or 12GHz!. Needs “Frequency

Extension” to drive/test higher

frequencies.

• Instantaneous BW limited

~ 200MHz.

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mm-Wave DUT docking & interfacing challenges

Sockets are limited in frequency (<30GHz) and pose high parasitic and no perfectly consistent mm-Wave contact resulting test errors.

Many 60 GHz DUTs are integrated with antennas.

Path Loss over the air (68dB @ 1meter/60GHz)

Crosstalk and Multipath especially for multisite

VSWR of socket and TL degrade Test Flatness. De-embedding?. 𝟏𝒏𝑯 𝑺𝒆𝒓𝒊𝒂𝒍 𝑷𝒂𝒓𝒂𝒔𝒊𝒕𝒄

@𝟑𝟎𝑮𝑯𝒛 = j𝛚𝑳 ≈ j200 ohm

𝟓𝟎𝒑𝑯 𝑺𝒆𝒓𝒊𝒂𝒍 𝑴𝒊𝒔𝒔𝒎𝒂𝒕𝒄𝒉 @𝟑𝟎𝑮𝑯𝒛

≈ j10 ohm

SiBEAM

WHD module

(Ali M. Niknejad)

Antennas

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More Challenges in WB and mm-Wave Test

Link Budget Example 1GHz BW @ 60GHz:

1 dB out comp. 60GHz converter (no PA): -20dBm

TX Back Off: 8dB

Maximum TX power: -28dBm

TX + DUT Antenna Gains: 20dB

1 Meter path loss: 68dB

Total over the air (OTA) loss: 48dB

Conclusion: Such stand alone converter can not support WB EVM testing OTA.

𝑅𝑋 𝐷𝑈𝑇 𝑁𝑜𝑖𝑠𝑒 𝐹𝑙𝑜𝑜𝑟: 𝑷𝑵𝒐𝒊𝒔𝒆 @ 𝟏𝑮𝑯𝒛 𝑩𝑾 = -174+10 𝒍𝒐𝒈𝟏𝟎𝟗+NF(𝟔𝒅𝑩 )= -78dBm

𝑅𝑋 𝐷𝑈𝑇 𝑆𝑖𝑔𝑛𝑎𝑙 𝐿𝑒𝑣𝑒𝑙: 𝑷𝑹𝒆𝒄𝒊𝒆𝒗𝒆𝒅 𝑺𝒊𝒈𝒏𝒂𝒍 = -28 dBm - 48= -76dBm

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Solution Approaches & RFIC Test Economics

“Frequency extension” NB or WB:

• Convert (or multiply) I/O Frequency of automatic tester, signal generator and test instruments to/from mm-Wave frequency.

Testing Modules integrated with Antennas :

• Employ wafer probing when relevant

Economic OTA testing or “Contact less”

probing.

UWB on load board E-Band converter 60GHz IQ converter 60GHz Transceiver

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Frequency conversion technical consideration IQ Conversion 101:

IF @ fLO

fLO

fLO

BBI

00/900

BBQ

IF1

IF2

BBI

00/900

BBQ

𝑰 + 𝑸

𝟐

𝑸 − 𝑰

𝟐

IF @ fLO

fLO

fLO

Ideal Up-Conversion

Ideal Down-Conversion

𝑩𝑩𝑰 = 𝑺𝒊𝒏(𝝎𝑳𝑶𝒕) ∙

𝑰+𝑸

𝟐𝑪𝒐𝒔 (𝝎𝑳𝑶 − 𝝎𝑩𝑩)𝒕

−𝑰−𝑸

𝟐𝑪𝒐𝒔 (𝝎𝑳𝑶 + 𝝎𝑩𝑩)𝒕

=

= 𝑰

𝟐𝑺𝒊𝒏 (𝝎𝑩𝑩)𝒕 +……

𝑩𝑩𝑸 = 𝑪𝒐𝒔(𝝎𝑳𝑶𝒕) ∙

𝑰+𝑸

𝟐𝑪𝒐𝒔 (𝝎𝑳𝑶 − 𝝎𝑩𝑩)𝒕 −

𝑰−𝑸

𝟐𝑪𝒐𝒔 (𝝎𝑳𝑶 + 𝝎𝑩𝑩)𝒕

=

= 𝑸

𝟐𝑪𝒐𝒔 (𝝎𝑩𝑩)𝒕 +…….

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Frequency conversion technical consideration Transceiver Frequency Plan using a Single Synthesizer:

Popular case : M=2, N=1.

32

21

RFLOLO

FFF

LO1, LO2

Generation:

= LO1

= LO2

GHzFF

F RFLOLO 20

32

21

GHzFF

F RFLOLO 20

32

21

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Frequency conversion technical consideration Ideal performance of 1/3, 2/3 frequency plan:

fRF @ 3fLO1

WB Signal IF @ fRF/3 RF=1LO2+1IF

fLO2 =

2*fLO1

fLO1 =

fRF/3

BBI

00/900

BBQ

IF1

IF2

fIF=fRF/3

𝑻𝑿𝟏𝟏 =desired output = 𝑪𝒐𝒔(𝟐𝝎𝑳𝑶𝒕) ∙𝑰+𝑸

𝟐𝑪𝒐𝒔 (𝝎𝑳𝑶 − 𝝎𝑩𝑩)𝒕 −

𝑰−𝑸

𝟐𝑪𝒐𝒔 (𝝎𝑳𝑶 + 𝝎𝑩𝑩)𝒕

= 𝑰+𝑸

𝟒𝑪𝒐𝒔 (𝟐𝝎𝑳𝑶 − 𝝎𝑳𝑶 + 𝝎𝑩𝑩)𝒕 + 𝑪𝒐𝒔 (𝟐𝝎𝑳𝑶 + 𝝎𝑳𝑶 − 𝝎𝑩𝑩)𝒕

- 𝑰−𝑸

𝟒𝑪𝒐𝒔 (𝟐𝝎𝑳𝑶 − 𝝎𝑳𝑶 − 𝝎𝑩𝑩)𝒕 + 𝑪𝒐𝒔 (𝟐𝝎𝑳𝑶 + 𝝎𝑳𝑶 + 𝝎𝑩𝑩)𝒕

= 𝑰+𝑸

𝟒𝑪𝒐𝒔 (𝟑𝝎𝑳𝑶 − 𝝎𝑩𝑩)𝒕 + ⋯ . -

𝑰−𝑸

𝟒𝑪𝒐𝒔 (𝟑𝝎𝑳𝑶 + 𝝎𝑩𝑩)𝒕 + ⋯

Outputs @ ω = 3 𝝎𝑳𝑶𝟏

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Frequency conversion technical consideration Inter-Modulations in Mixers:

𝑻𝑿𝟐𝟏 = Iinter-modulation IMD21 = In Band Impairment=

𝒂 ∙ 𝑪𝒐𝒔(𝟒𝝎𝑳𝑶𝒕) ∙𝑰+𝑸

𝟐𝑪𝒐𝒔 (𝝎𝑳𝑶 − 𝝎𝑩𝑩)𝒕 −

𝑰−𝑸

𝟐𝑪𝒐𝒔 (𝝎𝑳𝑶 + 𝝎𝑩𝑩)𝒕 =

a𝑰+𝑸

𝟒𝑪𝒐𝒔 (𝟑𝝎𝑳𝑶 + 𝝎𝑩𝑩)𝒕 + 𝑪𝒐𝒔 (𝟓𝝎𝑳𝑶 − 𝝎𝑩𝑩)𝒕 -

𝑰−𝑸

𝟒𝑪𝒐𝒔 (𝟑𝝎𝑳𝑶 − 𝝎𝑩𝑩)𝒕 + 𝑪𝒐𝒔 (𝟓𝝎𝑳𝑶 + 𝝎𝑩𝑩)𝒕

Outputs @ ω = 3 𝝎𝑳𝑶

𝑰𝑴𝑫𝒏𝒎 = ±𝒏𝒇𝑳𝑶 ± 𝒎𝒇𝑹𝑭 Where n, m integers 0, 1,2,3

Special interest should be paid for IMD products with m=1 which

inherently have higher power levels

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Frequency conversion technical consideration M21 Impairment in Heterodyne 1/3, 2/3f0:

Up converter (as well as Down converter) mixer present:

significant 2LO-1RF inter-modulation product around the same center frequency.

IF @ fRF/3 RF=1LO2+1IF

IM21=2LO2-1IF fRF

WB Signal

Intermod. a

fLO2 =

2*fLO1

fLO1 =

fRF/3

BBI

00/900

BBQ

IF1

IF2

fRF/3

a- Mixer IM21 suppression can be improved to a certain level by

improving Balun Balance

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Summary

• High mm-Wave wafer probing relevant when:

– Chip ASP and performance is critical as with PAs.

– Packaging or final module expensive as with MCMs.

• Socket testing is limited today to ~ 30GHz

• OTA testing is good for characterization and pose challenges in HVM environment.

• “Contact less” probing has potential advantages.