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A frequency mixing and sub-sampling based RF-measurement apparatus - - PowerPoint PPT Presentation
A frequency mixing and sub-sampling based RF-measurement apparatus - - PowerPoint PPT Presentation
A frequency mixing and sub-sampling based RF-measurement apparatus for IEEE 1149.4 Juha Hakkinen 1 , Pekka Syri 1 and Markku Moilanen 2 Department of Electrical and Information Engineering, Electronics Laboratory 1 , Optoelectronics and
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Outline
- Motivation and goal
- Solution, i.e. circuit realization
- Circuit characterization
- RF measurement demonstration, i.e. 3 GHz
VCO measurements
- Repeatability measurements
- Conclusions
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Motivation
Testing and tuning of high-frequency parts of electrical systems is extremely time consuming and requires expensive test equipment If IEEE 1149.4 could be used also for RF testing, the speed and cost improvements could be considerable in the future An emerging testing standard IEEE 1149.4 allows the access of selected locations in the PCB for low- frequency testing
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RF measurement in the IEEE 1149.4 environment
PC LF DUT
IEEE 1149.4 demo PCB
RF DUT IEEE 1149.4 capabilities demonstration environment DCU RF (2…3GHz) LF (DC…100kHz) Apparatus described in this presentation
SCANSTA 400
AC W/V/A
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The Apparatus
T pulse shaper
- 3 dB
ZABDC20-2400 fvco ≈ 2 GHz S/H φ φ φ fLO ≈ 1.9 GHz fclk (≈ 9.995 MHz) ≈ 2 GHz band-pass fIF (≈ 100 MHz) ≈ 4 GHz band-stop fout ≈ 50 kHz
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Sub-Sampling
time domain frequency domain
fi(t) fc fo(t) fo(t)
time T t time T t 100 MHz signal
fi(t)
100 MHz signal
|F(ω)| fc fRF =nfc+∆f f
LF copy of the 100 MHz signal
|G(ω)|
{ { { { { {
fc 2fc 3fc ∆f ∆f ∆f ∆f ∆f ∆f f ∆f
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Measured fout vs. fvco
30 40 50 60 70 80 90 100 110 2 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.1
fvco /GHz fout/kHz
fclk=9.985050 MHz fclk=9.988390 MHz fclk=9.991011 MHz
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∆fvco = fvco measurement error
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- 4
- 3
- 2
- 1
1 2 2.02 2.04 2.06 2.08 2.1
fvco/GHz ∆ fvco /kHz
fclk=9.985050 MHz fclk=9.988390 MHz fclk=9.991011 MHz
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Pout vs. Pin
- 41
- 40
- 39
- 38
- 37
- 36
- 35
- 34
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- 32
- 31
- 2
- 1
1 2 3
Pin/dBm Pout /dBm
2.0GHz 2.01GHz 2.02GHz 2.03GHz 2.04GHz 2.05GHz 2.06GHz 2.07GHz 2.08GHz 2.09GHz 2.1GHz
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VCO and CLK reference circuits
- fVCO = 3.23…3.98 GHz
- fCLK = 26 MHz
0.7…1.2V fvco VCO box: -3 dB attenuator (LAT-3) CLK box: 74F04 hex inverter
VCO
2.7V 3.2V Vtune 3.23…3.98 GHz FAN 2500 0.7…1.2V fvco VCO box: -3 dB attenuator (LAT-3) CLK box: 74F04 hex inverter
VCO
2.7V 3.2V Vtune 3.23…3.98 GHz FAN 2500
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VCO measurement setup
T pulse shaper
- 3 dB
external S/H φ φ φ fIF (≈ 100 MHz) fout ≈ 9…100 kHz (≈ 3.23… 3.98 GHz) fVCO (26.00001 MHz) DCU fCLK fLO ≈ 3.6 GHz
AC W/V/A
SCANSTA 400
IEEE 1149.4 demo PCB LF reference measurement
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fVCO(L) vs. Vtune
y = 0.2378x + 3.1093 3.2 3.24 3.28 3.32 3.36 3.4 3.44 0.4 0.6 0.8 1 1.2
Vtune/V fVCO(L)/GH z
measured LMS
⇒ tuning sensitivity = 237.8MHz/V (datasheet 250+/-3MHz/V)
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VCO tuning linearity
- 400
- 300
- 200
- 100
100 200 300 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3
Vtune/V fVCO(L)-fLMS/kHz
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Repeatability of measurements Attenuation of DCU
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- 28
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- 26
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- 24
3 3.05 3.1
fin/GHz Attenuation/dB
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Repeatability measurements LF output power of SCANSTA400
- 58.5
- 58
- 57.5
- 57
- 56.5
- 56
3 3.05 3.1
fin/GHz P/dBm
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Repeatability measurements
Attennuation of the DCU and LF output power of the SCANSTA400
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- 28
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- 25
- 24
3 3.02 3.04 3.06 3.08 3.1
fin/GHz Attennuation/dB
average maximum minimum average scansta maximum scansta minimum scansta attenuation of DCU (Pin=0dBm)
⇒ attenuation of the RF-to-LF circuitry and the output power of the SCANSTA400 vary about ±0.125 dB and ±0.15 dB, respectively
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Repeatability measurements Frequency measurement error
⇒the measurement uncertainty is roughly ±350 Hz
4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5 5.1 2.98 3 3.02 3.04 3.06 3.08 3.1 3.12
fin/GHz ferror/kHz
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Conclusions
- It is possible to make simple RF measurements in the
1149.4 environment
- Combination of mixing and sub-sampling were
successfully used to down-convert the RF signal into a low frequency suitable for the standard
- The DCU has to be carefully characterized and de-
embedded from the measurement system
- The repeatability of RF power measurement at the IEEE
1149.4 analogue outputs is ±0.15 dB
- Measurement uncertainty of RF frequency caused by