1. EMC Lab presentation

2. Objectives of the Lab Objectives
Understand basic set-up and methodology for characterization of emission of ICs according to IEC (1 ohm and TEM cell method and near-field scan)
Understand basic set-up and methodology for characterization of emission of ICs according to IEC (DPI and TEM cell method)
Characterizing the emission and the susceptibility of a commercial circuit
Test the influence of some circuit’s parameters on emission or immunity
Correlate S/Z parameters with susceptibility to RF disturbance

3. Planning of the Lab Day 1: emission measurement
Configuration of a spectrum analyzer for emission measurement
Measurement of conducted emission due to the switching of an I/O. Measurement in time and frequency domain
Effect of I/O options on electromagnetic emission
Use a near-field scan probe to locate current circulation and evaluate current characteristics
Use near-field scan probe to measure the influence of spread-spectrum frequency modulation on electromagnetic emission

4. Planning of the Lab Day 1: emission measurement
Case study presentation:
Slew
Drive
Vddrio = 3.3 V
Vdd_core_io = 1.2 V
Vddrio
Vdd_core_io
Vdd_core_io
Vddrio
Dig_Out
Dig_In
Vss_core_io
Vssrio
Vss_core_io
Vssrio
Vssrio
Vss_core_io
49 Ω
Drive
Slew
Reduced
High 1
Full
1 Ω

5. Planning of the Lab Day 1: emission measurement
1 Ω measurement of I/O noise in time domain
Observe simultaneously the buffer output voltage and the voltage captured by the 1 Ω probe
Compare the voltage profiles with the different I/O options

6. Planning of the Lab Day 1: emission measurement
1 Ω / 150 Ω measurements of I/O noise in frequency domain
Compare the noise in the four I/O options
1 Ω measurement

7. Planning of the Lab Day 1: emission measurement
Near field scan – evaluate current circulation

8. Microstrip line (w = 1 mm, h = 1.6 mm, L = 10 cm)
Planning of the Lab
Day 1: emission measurement
Near field scan – evaluate current circulation
Link between two CMOS inverters:
Magnetic-field probe
Inverter AHCT04
Inverter AHCT04
Microstrip line (w = 1 mm, h = 1.6 mm, L = 10 cm)
10 MHz
With magnetic near-field probe, locate the circulation of the current
What is the bandwidth of the current ?

9. Planning of the Lab Day 1: emission measurement
Near field scan – microcontroller and effect of spread-spectrum frequency modulation on emission
The microcontroller Freescale MPC5604B has the following configuration:
CPU running at 40 MHz
Internal clock produced by an on-chip PLL running at 80 MHz, synchronized by a 8 MHz quartz oscillator
13 I/O switching at 200 kHz
With a near-field probe, locate the main source of electromagnetic emission created by the microcontroller.
Test the influence of spread spectrum frequency modulation on PLL emission

10. Planning of the Lab Day 1: emission measurement
Near field scan – microcontroller and effect of spread-spectrum frequency modulation on emission
VDDHV/VSSHV (I/O supply)
5 I/O switching at 200 kHz
VDDHV_ADC/VSSHV_ADC (ADC supply)
VDDLV/VSSLV (Core + PLL supply)
8 I/O switching at 200 kHz
External quartz

11. Planning of the Lab Day 2: susceptibility measurement
Presentation of the DPI test bench. Injection on simple loads and computation of power
Analysis of bias tee and identification of operating frequency range.
Measurement of conducted susceptibility of LTC1798. Manual and automatic DPI tests.
Influence of the input filtering.
Analysis of the susceptibility curve. Comparison with S parameter profile.
Measurement of radiated susceptibility in TEM cell of LTC1798.

12. Planning of the Lab Day 2: susceptibility measurement Bias tee
C = 1 nH, L = 1 µH
S parameter characterization:

13. Planning of the Lab Day 2: susceptibility measurement
Case study presentation:
LTC from Linear Technology
Bandgap references
Input voltage = 2.7 V to 12.6 V
Output voltage = 2.5 V +/- 10 mV (0 – 70°c)
Output current = up to 10 mA

14. Planning of the Lab Optionally mounted
Day 2: susceptibility measurement
Test board:
4-layer board, TEM cell compatible
Connection to the disturbance to P1 SMA connector (input of the reference)
Optionally mounted

15. Planning of the Lab Day 2: susceptibility measurement
Observed failures : DC offset induced at the reference output
Injection on input, no filter, Femi = 300 MHz
Injection on input, no filter, Femi = 10 MHz

16. Planning of the Lab Day 2: susceptibility measurement
DPI injection on input pin - susceptibility threshold

17. Planning of the Lab Day 2: susceptibility measurement
DPI injection on output pin - susceptibility threshold

18. Port 1 = input, Port 2 = output
Planning of the Lab
Day 2: susceptibility measurement
Link with S parameter measurements of test board and bias tee
Port 1 = input, Port 2 = output

19. Planning of the Lab Day 2: susceptibility measurement
Radiated susceptibility test in TEM cell
Find the frequencies where the circuit is susceptible
Find the worst case orientation of the test board