electrical measurments for microwave devices

8/14/2019 Electrical Measurments for Microwave Devices

1/121 ANMEM0902Microwave Support Documentation

ELECTRICAL MEASUREMENTS

ELECTRICAL MEASURMENTS FOR MICROWAVE DEVICES

Selecting a section will link to its page.

A. GENERAL PRECAUTIONS 2

B. HANDLING PRECAUTIONS 2

C. BIAS CIRCUIT 31.) DC SUPPLY CIRCUIT 32.) RF BIAS CIRCUIT 4

D. MEASUREMENT SYSTEM DIAGRAMS 51.) POWER MEASUREMENT SYSTEM BLOCK DIAGRAM 5

Discrete and Partially Matched FETs

2.) POWER MEASUREMENT SYSTEM BLOCK DIAGRAM 6Internally Matched FETs

3.) IM3 MEASUREMENT SYSTEM BLOCK DIAGRAM 74.) PHASE DEVIATION MEASUREMENT SYSTEM BLOCK DIAGRAM 85.) PULSE POWER MEASUREMENT SYSTEM BLOCK DIAGRAM 9

Pulsed Drain Bias 6.) NOISE FIGURE AND ASSOCIATED GAIN MEASUREMENT SYSTEM BLOCK

DIAGRAM 107.) THERMAL RESISTANCE MEASUREMENT SYSTEM BLOCK DIAGRAM AND

MEASUREMENT PROCEDURE 11




A. GENERAL PRECAUTIONS

1) Observe recommended operating conditions and absolute maximum ratings:

VDS, IDS, VGS, IG, TCH.

Absolute Maximum Ratings are the limits one should not exceed under any conditions and doesnot mean actual applicable bias condition. Fujitsu recommends the following conditions for longlife and reliable operation.

TCH = 145C maxVDS = See the individual data sheetsVGS = VGS shall be set for the I DS (0.6 I DSS to 0.55 I DSS )IG = See the individual data sheets

2) Use a sequencing DC power supply.See the individual data sheets or Figure III-1.

3) Do not apply RF power until the FET is biased on. Turn-off RF power before removing bias.

4) Use only properly designed RF circuits and decoupling circuits to prevent bias circuit oscillations.Bias oscillations are one of the most common modes of failure for microwave GaAs FETs.Destruction of the FET often occurs in microseconds. Refer to the individual data sheets orFigure III-3 , for the recommended bias circuit configuration.

B. HANDLING PRECAUTIONS

GaAs FETS are sensitive to electrostatic discharge. Fujitsu ships all GaAs FETs in electrostaticprotection packaging. User must pay careful attention to the following precautions when takingFETs out of their packaging.

1) Personnel handling GaAs FETs should be properly grounded by a wristlet chain or equivalent.

2) When mounting the FET in a circuit, the circuit gate and drain connections should be shorted toground.

3) When soldering the FET leads, an iron with a grounded tip is required.


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10

5

-2

-4

-6

Vin: ON Vin: OFF

+Vout (V)

-Vout (V)

10 msec

+Vout (V)

-Vout (V)

Figure III-2. Switching Response of the Bias Circuit

2) RF Bias Circuit

The injection of bias voltages into a GaAs FET RF circuit is typically accomplished via a quarter-wave transformer line as shown in Figure III-3. It is intended to provide a DC connection to the GaAsFET gate and drain, while perturbing the RF performance characteristics as little as possible.

C2

C3

C1

R3 L1 C1, C2: 1000pF, ChipL1, L2 :

R1R3R4R2 :C3, C4:C5, C6:

L2

R4

R2R1

-VGS +VDS

High impedence /4 line

Low impedence /4 line

Figure III-3. Connection of the Bias Supply to the GaAs FET's

Low impedence /4 line

High impedence /4 line

C4

C6

C5Rg=R1 +R3 x R4

R3 + R4

Large inductor atRF frequency or /4 lineChosen for desiredVGS , IDS andgate impedance50 Chip1000pF feed thruabout 10 F

}



ELECTRICAL

DIRECTIONALCOUPLER

DC POWER SUPPLY

+VDD-VGG

D.U.T. TUNER

IGS

VDSVGS

ATTEN.

POWERMETER

POWER

SENSOR

RF POWERSOURCE

TUNERBIASTEE

BIASTEE

Rg *

* Use Fujitsu's recommended gate resistance (Rg) as indicatedon the data sheet for the device under test . Follow device handlingand bias precautions presented at the beginning of this section.

POWERMETER

POWER

SENSOR

IDS

50 term.

D. MEASUREMENT SYSTEM DIAGRAMS

1. POWER MEASUREMENT SYSTEM BLOCK DIAGRAM

Discrete and Partially Matched FETs




DIRECTIONALCOUPLER

DC POWER SUPPLY+VDD-VGG

IGS

VDSVGS

ATTEN.

POWERMETER

POWERSENSOR

POWERMETER

POWERSENSOR

RF POWERSOURCE

BIASTEE

DCBlock

50 term.

BIASTEE

Rg *

2. POWER MEASUREMENT SYSTEM BLOCK DIAGRAM

Internally Matched FETs

IDS

DCBlock

50 term.

DIRECTIONALCOUPLER

DIRECTIONALCOUPLER

RFAMP

DETECTOR DETECTOR

SCALERNETWORKANALYZER

50 term.

D.U.T.





POWERMETER

POWERSENSOR

DC POWER SUPPLY+VDD-VGG

IGS

VDS

ATTEN.

POWERMETER

POWERSENSOR

RF POWERSOURCE

Freq.=f

DCBlock

50 term.

BIASTEE

Rg *

IDS

DCBlock

50 term.

DIRECTIONALCOUPLER

SPECTRUMANALYZER

ATTEN.

3 dBHybrid

RF POWERSOURCEFreq.=f+ f

RFAMP

50 term.

Be sure that the power level of signals input to the spectrum analyzer remain in the linearrange of the analyzer's internal mixer.

3. IM3 MEASUREMENT SYSTEM BLOCK DIAGRAM

EFFECT OF A DRIVER AMPLIFIER ON TOTAL IMD

Degradation in IM3 = 20 log 1+10

where IM3(D) is the driver stage IM3IM3(F) is the final stage IM3

( )

IM3 (D) IM3 (F)

6

4

2

0 10 20 30IM3 (F) - IM3 (D)

D e g r a

d a

t i o n

i n I M 3 ( d B ) example: IM3 (D) = -40dBc

IM3 (F) = -30dBcIM3 = -30 + 2.4

= -27.6dBc

[ [IM3(D) - IM3(F)

20

50 term.

RFAMP

50 term.

VGS

VAR.ATTEN.

BIASTEE

DIRECTIONALCOUPLER D.U.T.


50




50 term.

DCBlock

4. PHASE DEVIATION MEASUREMENT SYSTEM BLOCK DIAGRAM

DIRECTIONALCOUPLER

DC POWER SUPPLY

+VDD-VGG

D.U.T.

IGS

VDSVGS

POWERMETER

POWERSENSOR

RF POWERSOURCE

BIASTEE

Rg *

IDS

DIRECTIONALCOUPLER

RFAMP

VECTORNETWORKANALYZER

50 term.

50 term.

ATTEN.

VAR.ATTEN.

CONVERTER/ TEST SET

REF TEST

VAR.ATTEN.

PHASESHIFTER

DCBlock

ATTEN.BIASTEE

DIRECTIONALCOUPLER

POWERMETER

POWERSENSOR

LOWPASS

FILTER



9/129 ANMEM0902Microwave Support


5. PULSE POWER MEASUREMENT SYSTEM BLOCK DIAGRAM

Pulsed Drain Bias

DC POWER SUPPLY

+VDD-VGG

IGS

VGS

PEAKPOWERMETER

POWERSENSOR

RF POWERSOURCE

Rg *

RFAMP

PULSEGENERATOR

ATTEN.

OSCILLO-SCOPE

PEAKPOWERMETER

Trig.CH-1CH-2

PulsedDrainBias

PULSEMODULATOR

D.U.T.BIASTEE

BIASTEE

DIRECTIONALCOUPLER

50 term.

VAR.ATTEN.

50 term.

50 term.

DCBlock

DCBlock

PULSEDRIVER

POWERSENSOR


Package Outlines




DC POWER SUPPLY

+VDD-VGG

D.U.T. TUNER

IGS

VDSVGS

NOISE FIGUREAND GAIN

METER

TUNERBIASTEE

BIASTEE

Rg *

LOCALOSCILLATOR

LOW NOISEAMPLIFIER

IDS

50 term. 50 term.

6. NOISE FIGURE AND ASSOCIATED GAINMEASUREMENT SYSTEM BLOCK DIAGRAM

MIXER

NOISESOURCE





MEASUREMENT PROCEDURE

Open and close switches S1, S2, S3, and S4 according to the timing diagram illustrated in Figure 2. The heatinterval should be much longer than the thermal response time of the device under test (10 seconds). Themeasurement interval should be as short as possible (less than 50 sec.). The constant measurement current(IM) is a small current so selected that the measurement power dissipation may be neglected compared to theheat power dissipation.

The measurement is made in the following manner:

a. VDS is set to a specified value.b. VGS is set to a specified value, or adjusted

to obtain a specified drain current I DS.c. VGS1 is measured during the pre-heatmeasurement interval.

d. VGS2 is measured during the post-heatmeasurement interval.

Then thermal resistance is calculated as follows:

Rth(Channel-Case) = (V GS 1-VGS 2)/(K x VDSx IDS )Where K is the thermal coefficient of V GS (mV/ C)

K is obtained in the following manner:

a. Short the DUT drain and source to ground.b. Adjust the gate forward current to the value IM.c. Measure V GS at two different ambient temperatures less than 100 C.

Then K is calculated as follows:

K=(VGSa -VGSb )/(Tb-Ta) where Tb>Ta

VGS Detector

DC POWER SUPPLY

+VDS-VGS

D.U.T.

IMIDS

S1 S2S4

S3

S1

S2

S3

S4

Figure 2. Switch Timing Diagram

VGS1 Heat Interval V GS2

MeasurementInterval

MeasurementInterval

Note: DC bias conditions and accept/reject criteria shall be included in individual device specifications.

7. THERMAL RESISTANCE MEASUREMENT SYSTEM BLOCK DIAGRAMAND MEASUREMENT PROCEDURE


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for further information please contact:

FUJITSU COMPOUND SEMICONDUCTOR, INC.2355 Zanker Rd.San Jose, CA 95131-1138, U. S. A.TEL: (408) 232-9500FAX: (408) 428-9111www.fcsi.fujitsu.com

FUJITSU QUANTUM DEVICES EUROPE, LTD.Network HouseNorreys DriveMaidenhead, Berkshire SL6 4FJUnited KingdomTEL: +44 (0) 1628 504800FAX: +44 (0) 1628 504888

FUJITSU QUANTUM DEVICES SINGAPORE PTE LTD.HONG KONG BRANCHRm. 1101, Ocean Centre, 5 Canton Rd. Tsim Sha Tsui,Kowloon, Hong KongTEL: +852-2377-0227FAX: +852-2377-3921

FUJITSU QUANTUM DEVICES LIMITEDBusiness Development Division11th Floor, Hachioji Daiichi-Seimei Bldg.3-20-6 Myojin-choHachioji-city, Tokyo, 192-0046, JapanTEL: +81-426-43-5885FAX: +81-426-43-5582

2001 FUJITSU COMPOUND SEMICONDUCTOR, INC.

Printed in U.S.A. FCSI012001M3.5K

electrical measurments for microwave devices

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