TEKBOX TBMDA-CDN25 Modulated Wideband Power Amplifier User Guide

TEKBOX TBMDA-CDN25 Modulated Wideband Power Amplifier

Introduction

Tekbox provides a complete solution for affordable pre-compliance conducted immunity testing:
Coupling Decoupling Networks along with suitable calibration adapters and 150 Ohm transitions; BCI probes, suitable modulated wideband power amplifiers and EMCview PRO software. A third-party spectrum analyzer with tracking generator serves as signal source.
The TBMDA-CDN25 modulated amplifier provides the necessary power, bandwidth and modulation for conducted immunity testing using CDNs and BCI probes in the frequency range from 100 kHz to 250 MHz. It is designed to be driven by signal generators or by tracking generators of spectrum analyzers. With a 1 dB compression point of up to 25 W in the frequency range 100 kHz to 250 MHz it can generate test levels class 1, class 2, class 3 and class X according to ISO / EN 61000-4-6. A built in AM / PM – modulator enables use of tracking generators as signal source. The TBMDA-CDN25 has sufficient gain to achieve maximum output power with 0 dBm provided by a spectrum analyzer tracking generator.
Besides 1 kHz, 80% AM, the TBMDA-CDN25 provides built in modulation capability to generate 1 kHz, 50% duty cycle PM signals. In PM mode, the TBMDA-CDN25 can also generate a 217 Hz Signal with 12.5% duty cycle in order to simulate mobile phone TDMA noise.

Application:
General-purpose wideband RF power amplifier
Wideband RF power amplifier for conducted immunity testing driving CDNs or BCI-probes Wideband RF power amplifier for radiated immunity testing, driving near field probes Wideband RF power amplifier for radiated 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
Dimensions:
32 cm x 28 cm x 13 cm, 5.7 kg

Electrical Specifications

Technical Data:

• Input / Output: 50 Ohm, N female

• Supply Voltage range: 110 V…240 V

• Supply power consumption: 108 W @ 220V

• Operating temperature range: -20°C to 50°C

• Frequency range: 100 kHz – 250 MHz

• Small signal gain: 47 dB typ.

• Gain flatness 100 kHz – 250 MHz / Pin = -3 dBm: 3.5 dB typ.

• Saturated output power @ 100 kHz / Pin = 0 dBm: 44.1 dBm (25.7 W) typ.

• Saturated output power @ 150 kHz / Pin = 0 dBm: 44.6 dBm (28.8 W) typ.

• Saturated output power @ 500 kHz / Pin = 0 dBm: 45.1 dBm (32.4 W) typ.

• Saturated output power @ 1 MHz / Pin = 0 dBm: 45.3 dBm (33.9 W) typ.

• Saturated output power @ 10 MHz / Pin = 0 dBm: 45.3 dBm (33.9 W) typ.

• Saturated output power @ 50 MHz / Pin = 0 dBm: 45.6 dBm (36.3 W) typ.

• Saturated output power @ 80 MHz / Pin = 0 dBm: 46.6 dBm (45.7 W) typ.

• Saturated output power @ 100 MHz / Pin = 0 dBm: 46.5 dBm (44.7 W) typ.

• Saturated output power @ 150 MHz / Pin = 0 dBm: 44.5 dBm (28.2 W) typ.

• Saturated output power @ 200 MHz / Pin = 0 dBm: 43.8 dBm (24 W) typ.

• Saturated output power @ 230 MHz / Pin = 0 dBm: 44.9 dBm (30.9 W) typ.

• Saturated output power @ 250 MHz / Pin = 0 dBm: 44.8 dBm (30.2 W) typ.

• 1dB output compression point @ 100 kHz: +43.7 dBm typ. (Pin: -5 dBm)

• 1dB output compression point @ 150 kHz: +44.1 dBm typ. (Pin: -4 dBm)

• 1dB output compression point @ 500 kHz: +44.6 dBm typ. (Pin: -3 dBm)

• 1dB output compression point @ 1 MHz: +45 dBm typ. (Pin: -3 dBm)

• 1dB output compression point @ 10 MHz: +45 dBm typ. (Pin: -2 dBm)

• 1dB output compression point @ 50 MHz: +45.6 dBm typ. (Pin: 1 dBm)

• 1dB output compression point @ 80 MHz: +46.5 dBm typ. (Pin: 1 dBm)

• 1dB output compression point @ 100 MHz: +46.5 dBm typ. (Pin: 0 dBm)

• 1dB output compression point @ 150 MHz: +42.9 dBm typ. (Pin: -4 dBm)

• 1dB output compression point @ 200 MHz: +42.2 dBm typ. (Pin: -4 dBm)

• 1dB output compression point @ 230 MHz: +44.1 dBm typ. (Pin: -3 dBm)

• 1dB output compression point @ 250 MHz: +43 dBm typ. (Pin: -4 dBm)

• 2nd harmonic, 100 MHz, Pout=46dBm: < – 12 dBc typ.

• 2nd harmonic, 100 MHz, Pout=40dBm: < – 15 dBc typ.

• 3rd harmonic, 100 MHz, Pout=46dBm: < – 22 dBc typ.

• 3rd harmonic, 100 MHz, Pout=40dBm: < – 22 dBc typ.
  Total harmonic distortion:

• 17.7% @100MHz, Pout=37dBm typ.

• 19.6% @100 MHz, Pout=40 dBm typ.

• 22.1% @100 MHz, Pout=43 dBm typ.

• 26.9% @100 MHz, Pout=46 dBm typ.

• Third order output intercept point: +51 dBm, @100 MHz, ∆ f = 2MHz, typ.

• Internal modulation frequency AM: 1 kHz ±20%

• Internal modulation frequencies PM: 1 kHz ±20%, 217 Hz ±20%

• Duty cycle, PM: 50% ±10% @ 1 kHz; 12.5% ±20% @ 217 Hz

Maximum ratings:
Maximum input power: +3 dBm
The output of the TBMDA-CDN25 is quite tolerant to output mismatch, however open or shorted load is not recommended, as it potentially can cause damage to the output transistor. When driving near field probes, current probes or any load of unknown impedance, it is highly recommended to insert a ≥ 3dB attenuator at the output of the amplifier in order to protect the output stage.

Gain flatness:

Small Signal Performance (@ Pin = – 10 dBm):

1 dB compression point:

Saturation (@ Pin = 0 dBm):

Modulation:
Zero span, 10 ms sweep time, peak detector:

Applications – radiated immunity

Immunity testing using a TEM cell

Immunity testing using near field probes

Radiated immunity EMC pre-compliance is typically a 2-step procedure. First, a TEM cell is used to investigate for immunity issues of the DUT. In case of any failure, near-field probes will be used to locate the sensitive circuitry on the PCBA.

TEM Cell field strength
A typical pre-compliance set up for immunity testing is typically not equipped with an E-field probe to measure the real field strength inside the TEM cell. However, the field strength can be calculated with sufficient accuracy for EMC pre-compliance set-ups.
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 use the simplified formula with sufficient accuracy.

• TBTC0: d = 2.8 cm -> E[V/m] = (√(P50Ω))35.7
• TBTC1: d = 5 cm -> E[V/m] = (√(P50Ω))20
• TBTC2: d = 10 cm -> E[V/m] = (√(P50Ω))10
• TBTC3: d = 15 cm -> E[V/m] = (√(P50Ω))6.66
• The power P in the formulas above hast to be entered in [Watt]
• P [W] = 0.001*(10^ (P[dBm]/10))

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]
---|---|---|---|---|---|---
0.1| -3| 43.86| 1245| 697| 349| 232
0.15| -3| 44.32| 1313| 735| 368| 245
0.5| -3| 44.57| 1351| 757| 378| 252
1| -3| 44.98| 1416| 793| 397| 264
10| -3| 44.76| 1381| 774| 387| 258
50| -3| 44.13| 1284| 719| 360| 240
80| -3| 45.07| 1431| 802| 401| 267
100| -3| 45.01| 1421| 796| 398| 265
150| -3| 43.77| 1232| 690| 345| 230
200| -3| 42.86| 1110| 622| 311| 207
230| -3| 44.01| 1267| 710| 355| 236
250| -3| 43.92| 1254| 702| 351| 234

The above output power is the RMS output power in case of a CW signal. Note that in case of 80% AM modulation, the RMS power of the modulated signal will be 5.1 dB lower than the RMS power of the CW signal.

Applications – conducted immunity, using CDNs

EN 61000-4-6 calibration set up using EMCview PRO

• Test Level 1: 1V RMS, 1 kHz / 80% AM modulated
• Test Level 2: 3V RMS, 1 kHz / 80% AM modulated
• Test Level 3: 10V RMS, 1 kHz / 80% AM modulated
• Test Level X: special (unspecified)

The specified test levels are open circuit voltages at the EUT port of the CDN.
The voltages measured during calibration must be multiplied by 3 to allow for the 50 Ohm to 150 Ohm conversion and again by 2 to reach the open circuit voltage.
Hence, the measured voltage at the output of the 150 Ohm to 50 Ohm adapter is 1/6 th the voltage of the desired stress level. In logarithmic figures, the measured voltage is 15.5 dB lower than the open circuit voltage.
Example: Test level 3

U0= 10V RMS open circuit voltage at the EUT port of the CDN = 10V/6 = 1.667V RMS at the output of the 100 Ohm to 50 Ohm adapter.
The required power at the output of the modulated amplifier is: U0/6 [dBm] + CDN insertion loss + 6 dB (Attenuator) + 5.1 dB (80% AM RMS)
Assuming 10 dB insertion loss for the CDN, the required RF power is: 17.4 dBm

• 10 dB + 6 dB + 5.1 dB = 38.5 dBm = 7.08 Watt

During calibration, EMCview Pro will make a stepped sweep, for each frequency adjusting the tracking generator level in order to achieve 17.4 dBm + 5.1 dB -30 dB = -7.5 dBm at the spectrum analyzer input. The tracking generator level table will then be used to set levels during the actual immunity test.

The typical insertion loss of a CDN with attached 150 Ohm to 50 Ohm adapter is 10 dB.
Adding the 6 dB attenuator and 5.1 dB for the AM RMS conversion results in a quasi-insertion loss of 10 dB + 6 dB + 5.1 dB = 21.1 dB.
For open circuit voltages of 1V, 3V and 10V, the corresponding power at the output of the 150 Ohm to 50 Ohm adapter is -2.6 dBm, 7 dBm, 17.4 dBm RMS CW. Add 5.1 dB to cover the RMS power of 80% AM modulation.
Consequently, the required power at the input of the 6 dB attenuator for class 1/2/3 is 18.5 dBm / 28.1 dBm / 38.5 dBm.
The table below reflects the insertion loss versus frequency of a real CDN in order to set the required input power for the TBMDA-CDN25.

Frequency [MHz]| TBMDA-

CDN25 output power to achieve stress level 1 [dBm]

| Corresponding TBMDA-CDN25

input power [dBm]

| TBMDA-

CDN25 output power to achieve stress level 2 [dBm]

| Corresponding TBMDA-CDN25

input power [dBm]

| TBMDA-

CDN25 output power to achieve stress level 3 [dBm]

| Corresponding TBMDA-CDN25

input power [dBm]

---|---|---|---|---|---|---
0.15| 17.2| -32 dBm| 27.2| -22 dBm| 37.2| -12 dBm
0.5| 16.7| -32 dBm| 26.7| -22 dBm| 36.7| -12 dBm
1| 17.5| -31 dBm| 27.5| -21 dBm| 37.5| -11 dBm
10| 18| -30 dBm| 28| -20 dBm| 38| -10 dBm
100| 18.9| -27 dBm| 28.9| -17 dBm| 38.4| -9 dBm
230| 19.8| -27 dBm| 29.8| -17 dBm| 39.8| -9 dBm

Table 4 – measured input power settings for the TBMDA-CDN25 in order to achieve stress level 1, 2 and 3
EMCview PRO has the capability to automatically adjust the tracking generator level in order to achieve the desired stress level voltage. The output is a calibration table, which is loaded and applied during the immunity test.

EN 61000-4-6 immunity test set up using EMCview PRO

Applications – conducted immunity, using BCI probes

EN 61000-4-6 specifies stress levels in terms of voltage and calibrates the immunity set up using a 300 Ohm loop. Other standards specify stress levels in terms of injected current.

EN 61000-4-6 300 Ohm loop BCI calibration set up using EMCview PRO

• Test Level 1: 1V RMS, 1 kHz / 80% AM modulated
• Test Level 2: 3V RMS, 1 kHz / 80% AM modulated
• Test Level 3: 10V RMS, 1 kHz / 80% AM modulated
• Test Level X: special (unspecified)

The specified test levels are open circuit voltages at the output of the calibration fixture.
The voltages measured during calibration must be multiplied by 3 to allow for the 50 Ohm to 150 Ohm conversion and again by 2 to reach the open circuit voltage.
Hence, the measured voltage at the output of the 150 Ohm to 50 Ohm adapter is 1/6th the voltage of the desired stress level. In logarithmic figures, the measured voltage is 15.5 dB lower than the open circuit voltage.

Example: Test level 3 U0= 10V RMS open circuit voltage at the output of the calibration fixture = 10V/6 = 1.667V RMS at the output of the 100 Ohm to 50 Ohm adapter.
The required power at the output of the modulated amplifier is:
U0/6 [dBm] + BCI probe insertion loss + 6 dB (Attenuator) + 5.1 dB (80% AM RMS)
Assuming 16 dB insertion loss for the BCI probe in a 300 Ohm loop, the required RF power is:
17.4 dBm + 16 dB + 6 dB + 5.1 dB = 44.5 dBm = 28.2 Watt

During calibration, EMCview Pro will make a stepped sweep, for each frequency adjusting the tracking generator level in order to achieve 17.4 dBm -30 dB = -12.6 dBm at the spectrum analyzer input. The tracking generator level table will then be used to set levels during the actual immunity test.

EN 61000-4-6 immunity test set up using a BCI probe and EMCview PRO

PC Software for immunity testing

Tekbox provides two software versions for EMC pre-compliance measurements
EMCview provides a feature to control the tracking generator output frequency and level and carry out sweeps with constant tracking generator level.
EMCview PRO provides a more sophisticated feature, which is able to carry out calibration sweeps for CDN and BCI based set ups. The resulting calibration file is used to set the tracking generator level during the immunity test sweep.
Tekbox EMCview currently supports Rigol, Siglent, Owon, R&S FPC and FPH series spectrum analyzers.

WARNING:
Never connect the output of the TBMDA-CDN25 directly to the input of a spectrum analyzer. Check the maximum input ratings of the spectrum analyzer and protect it with an appropriate attenuator.
Open or shorted load is not recommended, potentially can cause damage of the RF output stage. Use a ≥ 3 dB attenuator at the amplifier output, when driving loads with poor SWR.
Example: Rigol DSA815 – maximum input power rating: +20dBm

Ordering Information

1 pc 6 dB attenuator, 1 pc 30dB / 50W attenuator with N-connectors, C13 Schuko power cord
TBMDA-CDN25-US| modulated power amplifier, 2 pcs 75cm N-male to N-male cables, 1 pc 6 dB attenuator, 1 pc 30dB / 50W attenuator with N-connectors, C13 US power cord
TBMDA-CDN25-UK| modulated power amplifier, 2 pcs 75cm N-male to N-male cables, 1 pc 6 dB attenuator, 1 pc 30dB / 50W attenuator with N-connectors, C13 English power cord
TBMDA-CDN25-AU| modulated power amplifier, 2 pcs 75cm N-male to N-male cables, 1 pc 6 dB attenuator, 1 pc 30dB / 50W attenuator with N-connectors, C13 Australian power cord

History

www.tekbox.com
TekBox Digital Solutions Vietnam Pte. Ltd.
Factory 4, F5, Lot I-3B-1, Saigon Hi-Tech Park, Tan Phu Ward, District 9, Ho Chi Minh City, Vietnam

References

• Tekbox Digital Solutions |

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