Langer EMV-Technik GmbH

Our interference emission and interference immunity EMC measurement technology as well as the IC test system are used mainly in the development stage and are in worldwide demand.

Developers and designers gain new perspectives and more efficient working strategies for module- and IC developments with the EMC know how and measurement technology of Langer EMV-Technik GmbH.

The individual pre-compliance consulting services provided by Langer EMV-Technik GmbH help developers and designers quickly find solutions to complex EMC problems in IC, device, and module development.

 Press Releases

• ICR Near-field analysis in the micrometer range and its advantages (20241023)

  Near-field probes have become essential in the development of electrical assemblies. They are used successfully in both high-frequency technology and EMC technology. They are used to evaluate simulation values, locate sourcesof interference and carry out real-time monitoring. Near-field probes have the following advantages:

  1. a low feedback effect on the measuring system due to contactless measurement
  2. varied application possibilities due to optimized tip design
  3. due to their small size, even structures that are difficult to reach can be examined
  4. near-field probes cover a broad frequency spectrum
  5. the probes can be used for measurements in the frequency and time range
  6. easy handling

  These advantages make it easy to integrate the near-field probes into the development process.
  Another aspect and the greatest advantage of near-field analysis is the possibility of investigating various
  interactions in devices (e.g. magnetic fields). The magnetic field and the electric field can be measured separately.
  This makes it possible to assess the effect of the electric field separately from the effect of the magnetic field. The
  associated gain in degrees of freedom for assessing the correlation of effects is considerable, as distributions of
  currents and voltages can also be derived from the field distributions.
  
  To utilize this advantage of near-field measurement, Langer EMV-Technik GmbH probes are designed in such a way that magnetic field probes, for example, are shielded against (the penetration of) electric fields.

  Another positive aspect of near-field measurement with near-field probes is the spatial resolution of measured values. Depending on the size of the near-field probe, measurement volumes can be measured with a higher or
  lower resolution. For example, the field distribution of entire assemblies and the smallest circuits can be measured and displayed graphically. The near-field microprobes of the ICR series are particularly suitable for the field
  distribution of circuits. These probes are characterized by a high spatial resolution of approx. 70 -250 μm. With this resolution, field distributions of integrated circuits can be recorded and evaluated. Figure 1 and Figure 2, for
  example, show the field distribution of the processor chip of a Raspberry Pi at different spectral frequencies. The field distributions result from the internal switching processes of the IC.

  

  Figure 1: Field decoupling measured with ICR HH150-27 at 25MHz         

  

  Figure 2: Field decoupling measured with ICR HH150-27 at 163.7MHz
  
  The figures show the different activity of the circuit at different frequencies. These activities reflect the processes and functions of the circuit and depend, for example, on the technology of the IC and the software or firmware. In comparison, the field distribution of the memory circuit of the Raspberry Pi shows the diversity of the structure.

  

  Figure 3: Field decoupling measured at memory IC with ICR HH150-27 at 18MHz

  

  Figure 4: Field decoupling measured on memory IC with ICR HH150-27 at 24MHz

  Figures 3 and 4 show the activity of the IC distributed over the entire chip surface. It is generated by the function of the IC distributed over the chip. Under the aspect of:

  • Fault diagnosis
  • quality assurance
  • Optimization of integrated circuit components

  this type of near-field testing is an asset not only in development but also in troubleshooting finished devices. The advantages of the high spatial resolution and the wide frequency range are particularly useful in the investigation of safety-critical functions of integrated circuits. This is currently being used particularly in the area of circuit security. In so-called side-channel attacks, circuits are exposed to certain signals in the time domain and the reaction of the circuit is investigated at various positions using field strength increases. Langer EMV-Technik offers not only the near-field probes for measuring the reaction, but also the pulsed field generators for feeding in the interference signals. The spatial resolution of the injected pulsed fields is also in the range of approx. 200-300 μm. Near fields are one of the most important sources of information for basic EMC investigations. Therefore, near-field probes are the eyes of the developers within the device.

• P512 and DPI (20241029)

  

  Figure 1: Test PCB for DPI according to IEC 62132-4

  The weak points for the susceptibility to interference in modern electronics often lie in the circuits (ICs) of the assemblies. However, the increasing integration density and smaller semiconductor structures in the
  ICs also change their interference behavior. Fast and high-frequency interference, which was compensated for in ICs of older generations by the larger structures or did not become effective due to the high inductance of the longer interference current paths, is becoming increasingly relevant for new types of ICs. To test an IC for its susceptibility to interference from high-frequency signals, RF power can be fed directly into the pins in a conducted manner.
  This method of directly feeding RF power (DPI) into IC pins is generally carried out using a test PCB in accordance with the standard (IEC 62132-4). According to the standard board, each pin to be tested is
  provided with a coupling capacitance of 6.8 nF and a subsequent RF-compatible connector (e.g. SMA). By connecting a power amplifier to the connectors, RF power can be fed directly into the pin. The upper
  limit frequency up to which such a DPI test is carried out is 1 GHz. In the automotive sector, tests are carried out up to 3 GHz.

  For DPI tests involving ICs with more than 100 pins, the design of the test PCB quickly becomes complex and confusing. In this case, either only a small number of relevant pins are tested, or several test PCBs are designed, each targeting different pin groups.

  The new product from Langer EMV-Technik, the P512 probe, is capable of coupling RF power of up to 12 GHz into IC pins. A special contact system with a large-area ground connection is used for this purpose. The probe's cut-off frequency of 12 GHz was measured using an IC striplinewithin the ground system.

  

  Figure 2: Measurement of the cut-off frequency of the P512 on a stripline

  The main advantage of using the P512 is the frequency range up to 12 GHz for the coupling of RF power. ICs manufactured using flip-chip technology and housed in a BGA package are particularly susceptible in this higher frequency range. Further advantages result from the special design of the probe in combination with the ground system included in the set. The IC pins no longer have to be contacted separately via the SMA connector of the respective pin in order to couple in
  RF power; instead, the probe itself is connected to the power amplifier with the SMA connector on the back of the probe. The pins are then contacted using the tip of the probe, which can be freely positioned on each pin of the IC. This eliminates the need to switch between testing two pins and makes it possible in principle to automate the measurement. The 6.8 nF coupling capacitance is located inside the probe and no longer needs to be taken into account when designing the test PCB.

  
  
  Use as RF probe head

  The P512 can also be used as an RF probe for measuring high-frequency signals up to 12 GHz. The measurement takes place in the same ground system as the coupling. The advantage of
  freely contacting of pins as already mentioned for coupling, is therefore retained. Due to the ground contact of the sample directly next to the measuring tip, potential coupling loops remain minimal, which leads to reduced feedback in the measurement. When measuring high-frequency useful signals, the signal may be capacitively loaded and distorted by the 6.8 nF. In such a case, the internal coupling capacitance of the probe can be adjusted to any value in the pF range.

• TroubleStar ESD / Burst Practical example for ESD interference suppression (20241030)

  he development of IC technology has significantly reduced the structural widths of silicon, which has increased the potential risk of interference.

  The higher sensitivity to interference is caused by the lower supply voltages, higher switching speeds and lower switching thresholds of the ICs.

  This also increases the sensitivity to ESD interference in particular.

  Interference suppression and fault isolation are usually carried out with an ESD generator (ESD gun)

  .

  The ESD gun is a very coarse tool that exposes the assembly in a large area and does not allow the weak points to be located. It is almost impossible to locate the specific weak points quickly.

  A lot of time is wasted on trial and error. For instance, if the tip of the ESD gun is placed on the left-hand metal component of the test object (LAN socket) and the gun head is swung downwards onto the test object, the processor will malfunction (display failure of the device under test).

  The fault location cannot be narrowed down any further with the ESD gun. Now it is traditionally necessary to continue working by trial and error. Based on assumptions, various countermeasures are added and tested until success is achieved.

  Solution with TroubleStar ESD / Burst

  This practical example shows a new method for implementing this interference suppression more quickly. This requires new strategies and equipment technology.

  The core component is the TroubleStar ESD / Burst (TS 23) with a pulse rise time of 1.5 ns and differential outputs.

  How does the error occur?

  Figure 1 shows the test device in the position with the ESD gun in which the fault occurs.

  Working hypothesis

  From the knowledge of how the ESD gun works and the structure of the test device, it is possible to guess that the SSD card or the processor may play a role in the fault scenario.

  The tip of the ESD gun directs the interference pulse into a metallic component (LAN socket) of the device under test. As a side effect, this ESD gun generates a 200 ps steep E-field decoupling at the gun head, which also acts on the device under test.

  It is unclear whether the device under test is disturbed by the ESD pulse from the tip (LAN socket) or by the parasitic effect of the E-field decoupling via the gun head. There are two places where interference suppression can be continued: at the network socket or at the point where the gun head acts.

  Figure 1 shows that an SSD card is located in the immediate vicinity of the gun head. The electric field of the ESD gun head generates a current pulse that is coupled through the heat sink of the SSD card and capacitively to the circuit board of the SSD card and can therefore cause the SSD card to fail.

  These and other hypotheses are tested with the TS 23 interference generator.

  

  The first step is to check whether the microprocessor is sufficiently resistant to interference. A pulse current is sent once through the metal insert (A, B in Figure 2) of the microprocessor using the differential output of the TS 23 interference generator. This generates an ESD-like magnetic field in the processor underneath. Next, the interference voltage of the
  TS 23 generator is applied between the metal insert and the ground (in Figure 2: B, C). There was no influence on the processor. This virtually eliminates any direct influence on the processor via its own heat sink.

  It is suspected that the SSD card has a corresponding vulnerability.  

  A microprocessor with an oscillating quartz crystal is located on the SSD PCB directly under the SSD card heat sink. The SSD card is insulated from its heat sink. This allows an electric field to build up between the heat sink and the assembly (microprocessor, oscillating quartz crystal). A capacitive displacement current of the electric field couples into the conduction of the oscillating crystal. This current flows through the protective diode of the input of the oscillator circuit and raises the output voltage of the quartz crystal above the switching threshold of the oscillator input. The input no longer receives a crystal signal and the oscillator circuit no longer emits a clock signal for a few microseconds.

  The microcontroller is no longer clocked for this time and stops. Communication with the processor is interrupted. The processor goes into an error state (display failure).

  To prove this, a voltage is applied between the SSD heat sink and the SSD circuit board using the differential output of the TroubleStar ESD / Burst to generate an ESD-like field between the two (in Figure 2: D).

  This measure led to the described failure of the test device. The error is caused by an interference voltage difference between the SSD heat sink and the SSD circuit board.

  Furthermore, the connector of the SSD card to the electronics board is tested for interference immunity. The differential output of the TroubleStar ESD / Burst is connected to the electronic ground of the SSD PCB and the ground of the board (in Figure 2: E) in order to couple an ESD-like current via the connector.

  In addition, other parts of the circuit can be examined using a magnetic field probe fed differentially by the TS 23 (in Figure 2: F), for example.

  Countermeasures

  

  n order to short-circuit the electrical field between the heat sink and the SSD circuit board, both metal systems must be electrically connected twice if possible, e.g. at points M2 and M3 (Figure 3).

  To reduce the load on the PCB connector, the heat sink can also be connected to the ground of the electronics board M1 (Figure 3).

  Countermeasures at M2 and M3 were successfull.

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