Tekbox TBMDA3B User guide

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TBMDA3

Modulated Wideband Power Amplifier

1 Introduction

The TBMDA3 modulated wideband power amplifier is designed in order to create an inexpensive signal source for immunity testing of electronic building blocks and products. It is designed to be driven by the tracking generator output of spectrum analyzers. With an input power range of -5dBm…0dBm, it can boost the output power of a tracking generator up to 5W. The TBMDA3 is ideal to drive Tekbox near field probes in order to find the sensitive spot of an electronic circuit or to create electric fields up to 550V/m when driving the Tekbox TEM Cell TBTC0, 300V/m when driving the TBTC1, 150V/m when driving the TBTC2 or 100V/m when driving the TBTC3. Test signals for immunity testing can be CW, AM or PM modulated. Consequently, the TBMDA3 provides built in modulation capability to generate 1 kHz AM or PM signals. In PM mode, the TBMDA3 can also generate a 217 Hz Signal with 12.5% duty cycle in order to simulate mobile phone TDMA noise.

Picture 1 – TBMDA3 modulated wideband driver amplifier, front view

Picture 2 – TBMDA3 modulated wideband driver amplifier, rear view

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3 MHz

7 MHz

10 MHz

25 MHz

100 MHz

200 MHz

300 MHz

400 MHz

500 MHz

22.5 dB

39.6 dB

42.7 dB

44.7 dB

44.4 dB

43.7 dB

42.6 dB

42.3 dB

600 MHz

700 MHz

800 MHz

900 MHz

1 GHz

1.1 GHz

1.2 GHz

41.8 dB

41.9 dB

40.6 dB

41.5 dB

39.9 dB

37.5 dB

29.8 dB

TBMDA3

Modulated Wideband Power Amplifier

Application:

General-purpose power amplifier Signal source for immunity testing, driving near field probes Signal source for immunity testing, driving TEM Cells

Features:

CW amplifier (modulation off) 1 kHz, 80% AM modulation 1 kHz, 50% duty cycle pulse modulation 217 Hz, 12.5% duty cycle pulse modulation

2 Electrical Specifications

Technical Data:

Input / Output: 50 Ohm, N female Supply Voltage range: 110 V…240 V Supply power consumption: 20 W Maximum input power: +3 dBm Operating temperature range: -20°C to 50°C Frequency range: 10 MHz – 1 GHz 1dB output compression point @ 10MHz: +36 dBm typ. 1dB output compression point @ 100 MHz: +37 dBm typ. 1dB output compression point @ 500 MHz: +36 dBm typ. 1dB output compression point @ 1 GHz: +34 dBm typ. Noise figure: 9 dB Harmonics: < - 10 dBc typ. Internal modulation frequency AM: 1 kHz ±10% Internal modulation frequencies PM: 1 kHz ±10%, 217 Hz ±20% Duty cycle, PM: 50% ±10% @ 1 kHz; 12.5% ±20% @ 217 Hz Gain:

Table 1 – TBMDA3 gain

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Frequency

[MHz]

Output power

@ -10 dBm input

power [dBm]

Output power

@ -5 dBm input

power [dBm]

Output power

@ -4 dBm input

power [dBm]

Output power

@ -3 dBm input

power [dBm]

Output power

@ -2 dBm input

power [dBm]

Output power

@ -1 dBm input

power [dBm]

Output power

@ 0 dBm input

power [dBm]

3

11.5

17

18.3

19.6

20.7

21.3

21.4 7 29.6

34.2

34.7

35

35.4

35.6

35.9

10

32.7

36.3

36.7

37

37.3

37.5

37.7

25

34.7

37.4

37.7

37.9

38

38.1

38.2

50

34.7

37.3

37.6

37.8

37.9

38.1

38.2

100

34.4

37.2

37.5

37.7

37.9

38

38.1

200

33.7

36.5

36.9

37.1

37.4

37.7

37.9

300

33.3

36.1

36.5

36.9

37.2

37.4

37.6

400

32.6

35.6

35.9

36.2

36.5

36.7

36.8

500

32.3

35.4

35.7

35.9

36

36.1

36.2

600

31.8

35.1

35.4

35.6

35.7

35.8

35.9

700

31.9

34.6

34.8

34.9

35

800

30.6

33

33.3

900

31.5

34.1

34.5

34.6

1000

29.9

33.3

33.6

34

34.3

34.5

34.7

1100

27.5

29.9

30.5

30.8

31

31.2

31.3

1200

19.8

23.6

24.3

25.9

25.3

25.5

25.8

10

12

14

16

18

20

22

24

26

28

30

32

34

36

38

40

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300

Output power versus frequency

Output power @ -10 dBm input power [dBm]

Output power @ -5 dBm input power [dBm]

Output power @ -4 dBm input power [dBm]

Output power @ -3 dBm input power [dBm]

Output power

TBMDA3

Modulated Wideband Power Amplifier

Figure 1 – TBMDA3, output power versus frequency, 3MHz – 1.2GHz

 Comment to the Table 1, 2 and Figure1: Units with serial number above TBMDA318014 have 2dB higher

gain, but the same saturated output power (-10dBm input power ->-12dBm input power, etc.)

Table 2 – TBMDA3 power table

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TBMDA3

Modulated Wideband Power Amplifier

Figure 2 – 1 kHz, 80 % AM envelope, 500 MHz

Figure 3 – 1 kHz, 50 % PM envelope, 500 MHz

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TBMDA3

Modulated Wideband Power Amplifier

Figure 4 – 217 Hz, 12.5 % PM envelope, 500 MHz

Figure 5 – CW, harmonics, 200 MHz

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TBMDA3

Modulated Wideband Power Amplifier

3 Applications

Immunity testing using a TEM cell

Figure 6 – immunity testing set up

Immunity testing using near field probes

Figure 7 – immunity testing set up

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Frequency [MHz]

Input power

[dBm]

Output power

[dBm]

Field strength

TBTC0 [V/m]

Field strength

TBTC1 [V/m]

Field strength

TBTC2 [V/m]

Field strength

TBTC3 [V/m]

7

-5

34.2

409

229

115

76

10

-5

36.3

521

292

146

97

25

-5

37.4

592

332

166

110

50

-5

37.3

585

328

164

109

100

-5

37.2

578

324

162

108

200

-5

36.5

534

299

149

100

300

-5

36.1

510

285

143

95

400

-5

35.6

481

269

135

90

500

-5

35.4

470

263

132

88

600

-5

35.1

454

254

127

n.a

700

-5

34.6

429

240

120

n.a

800

-5

33

357

200

100

n.a

900

-5

34.1

405

227

113

n.a

1000

-5

33.3

369

207

103

n.a

TBMDA3

Modulated Wideband Power Amplifier

4 TEM Cell field strength

A typical pre compliance set up for immunity testing is typically not sophisticated enough to measure the real field strength inside the TEM cell. However, the field strength can be approximated mathematically.

The E-field (V/m) between septum and lower (upper) wall of a TEM cell is E = V/d where V is the RMS voltage of the applied signal and d is the distance between septum and lower (upper) wall. This is based on the simplified assumption that the E field would be perfectly homogenous/evenly distributed. A more practical formula is E = V*Cor/d where Cor is a correction factor for the average field strength over the volume of the DUT derived from the analysis of the field distribution over the cross section of the cell.

Assuming the DUT is placed in the center of the cell and in the middle between bottom wall and septum, we can however use the simplified formula with sufficient accuracy.

TBTC0: d = 2.8 cm -> E TBTC1: d = 5 cm -> E TBTC2: d = 10 cm -> E TBTC3: d = 15 cm -> E

The power P in the formulas above hast to be entered in [Watt] P

= 0.001*(10^ (P

[W]

[dBm]

= (√(P*50Ω))*35.7

[V/m]

= (√(P*50Ω))*20

[V/m]

= (√(P*50Ω))*10

[V/m]

= (√(P*50Ω))*6.66

[V/m]

/10))

Table 3 – calculated field strength for TBMDA3 driving Tekbox TEM cells

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TBMDA3

Modulated Wideband Power Amplifier

5 PC Software for immunity testing

The Tekbox EMCview SW is regularly updated and now supports immunity testing with a feature for automated tracking generator control. This significantly simplifies immunity testing, especially in case of repeated testing during validation of DUT modifications/improvements.

Tekbox EMCview currently supports Rigol, Siglent, R&S FPC and FPH series spectrum analyzers.

Figure 8 – screenshot of the tracking generator control feature of EMCview

WARNING: Never connect the output of the TBMDA3 directly to the input of a

spectrum analyzer. Check the maximum input ratings of the spectrum analyzer and protect it with an appropriate attenuator.

Example: Rigol DSA815 – maximum input power rating: +20dBm

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Part Number

Description

TBMDA3

modulated power amplifier, 2 pcs 75cm N-male to N-male cables, 1 pc 30dB / 10W attenuator with N-connectors, power cord

Version

Date

Author

Changes

V1.0

2.6.2018

Mayerhofer

Creation of the document

V1.1

6.9.2018

Mayerhofer

Correction of Chapter 6

TBMDA3

Modulated Wideband Power Amplifier

6 Ordering Information

7 History

Table 5 – Ordering Information

Table 6 – History