In this paper, the impact of temperature on the electromagnetic susceptibility
of operational ampli¯ers at di®erent frequencies is presented. The IEC 62132-4 direct power
injection standard has been used with several commercials operational ampli¯ers in a printed
circuit board speci¯cally fabricated. The results show that the susceptibility of the operationals
ampli¯er is reduced with the temperature.Peer ReviewedPostprint (published version

Fernández García, Raúl

Gil Galí, Ignacio

English

In this paper the impact of temperature on the electromagnetic susceptibility of operational amplifiers at different frequencies is presented. The IEC 62132-4 direct power injection standard has been used with several commercials operational amplifiers in a printed circuit board specifically fabricated. The results show that the susceptibility of the operationals amplifier is reduced with the temperature.Peer ReviewedPostprint (author’s final draft

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Impact of temperature on the electromagnetic compatibility susceptibility of operational amplifiers

Progress In Electromagnetics Research Symposium Proceedings, Moscow, Russia, August 19–23, 2012 1063Impact of Temperature on the Electromagnetic Susceptibility ofOperational AmplifiersR. Ferna´ndez-Garc´ıa and I. GilDepartment of Electronic EngineeringUniversitat Polite`cnica de Catalunya, Colom 1, Terrassa 08222, SpainAbstract— In this paper, the impact of temperature on the electromagnetic susceptibilityof operational amplifiers at different frequencies is presented. The IEC 62132-4 direct powerinjection standard has been used with several commercials operational amplifiers in a printedcircuit board specifically fabricated. The results show that the susceptibility of the operationalsamplifier is reduced with the temperature.1. INTRODUCTIONOver recent years, due to the increasing demand for wireless operation electronic devices, a severeand complex electromagnetic pollution environment has been created. Therefore, the susceptibilityto Radiofrequency Interference (RFI) has become a more important constraint for integrated circuitdesigners, particularly for analogue integrated circuits (ICs), which are the most sensitive circuitsto RFI [1]. In order to characterize the IC susceptibility different standards have been proposed andthe IEC 62132-4 Direct Power Injection (DPI) is one of the most extensively used [2]. In this work,the IEC 62132-4 standard has been used in order to characterize the most widely known analogdevice, the operational amplifier (OpAmp). In this case, unlike others works, where the operationalamplifier susceptibility is evaluated [3, 4], the temperature has been taking into account. The impactof the temperature can be critical in a lot of safety application, i.e., automotive, where the electronicequipments located near the engine should resist, under normal operation conditions, temperaturesabout 100◦C.2. EXPERIMENTALFigure 1(a) shows the experimental fabricated PCB. The PCB dimensions are 8×8 cm2 and as it canbe observed a symmetrical microstrip layout with same electrical length traces and characteristicimpedance, Z0 = 50Ω, has been used. With this layout, all the injection ports present identicalbehavior. In order to investigate the operational amplifier susceptibility, a follower topology hasbeen selected, as a worst EMI case [3]. Moreover, all the devices under test are mounted on a DIP-8package in combination with an 8 pin dual in line IC socket. The prototype has been fabricated onthe commercial Rogers RO3010 substrate (dielectric constant εr = 10.2, thickness h = 1.27mm,tan δ = 0.0023) in order to have high performance above 1GHz.The susceptibility to electromagnetic interference has been evaluated under the standard IEC62132-4 DPI [2] which is a very popular and efficient method to apply a conducted interferencedisturbance to a component. Fig. 1(b) describes the DPI setup. It consists of a RF signal generator(a) (b)Figure 1: (a) PCB specifically designed for this experiment. (b) Experimental setup.1064 PIERS Proceedings, Moscow, Russia, August 19–23, 2012(providing the RFI disturbance) directly connected to a directional coupler in order to measure theactual level of power injected into the DUT with a power meter. A power supply provides theDC voltage to the integrated circuit and an oscilloscope is used to measure the OpAmps offsetvoltage due to RFI. Notice that the PCB is located in an oven in order to control the temperatureof the devices under test. The RF interference has been swept from 10MHz to 1GHz with a inputpower forward level up to 10 dBm, at three temperatures: 25◦C, 50◦C and 75◦C. The experimentshave been performed for two types of operational amplifiers, the well-known LM741 operationalamplifier and the TL081, which is wide bandwidth JFET input operational amplifier.3. RESULTSFigure 2 shows the frequency dependency of the offset voltage when a power level of 0 dBm isinjected into the operational amplifier non-inverter input at room temperature (25◦C). The resultsare shown for two different integrated circuits, LM741 and TL081. It is observed that the offsetvoltage of LM741 reach a value about 300mV, meanwhile the TL081 reach a voltage offset below40mV.In order to evaluate the impact of the temperature, both operational amplifiers have beensubjected at different temperatures. The results are shown in Fig. 3. It both cases the offsetvoltage is reduced when the temperature is increased. For instance, for a RFI interference of100MHz the offset voltage drops from 360mV at 25◦C to 328mV at 75◦C for the LM741, whichrepresents a reduction 8.9%. At the same frequency, the reduction of TL081 offset voltage dropsfrom 22.3mV to 13.8mV, which corresponds to a 38% offset voltage reduction.Notice that, although the absolute offset voltage reduction is higher in case of LM741, the relativereduction is lower than in case of TL081 due to the high offset voltage at room temperature. Fig. 4details the offset voltage temperature dependence in case of 100MHz RFI with three different RFIpower levels, −20 dBm, −10 dBm and 0 dBm for LM741 and −10 dBm, 0 dBm and 10 dBm forTL081.Figure 2: Operational amplifier offset voltage when a RFI interference of 0 dBm is injected at the inverterinput at room temperature.Figure 3: Operational amplifier offset voltage when a RFI interference of 0 dBm is injected at the inverterinput (f = 100MHz). The results are shown for three temperatures: 25◦C, 50◦C and 75◦C.Progress In Electromagnetics Research Symposium Proceedings, Moscow, Russia, August 19–23, 2012 106510dBm @100MHz -10dBm @100MHz 0dBm @100MHz LM741 TL081 Figure 4: Operational amplifier offset voltage temperature dependence. The results are show for threedifferent RFI power injection levels.As in Fig. 2, the offset voltage of LM741 is about one order of magnitude worse than TL081. Inorder to achieve similar offset voltage in both integrated circuits, the power injection level of TL081should be increased 10 dBm. The experimental results of Fig. 4 confirm the voltage reduction trendwhen the temperature is increased. A deeply investigation should be done in order to explain thephysical reason of this behavior. However, one brief explanation can be the improvement of thenon-linearity behavior of the transistor at high temperatures.4. CONCLUSIONSIn this paper, the impact of temperature on the electromagnetic susceptibility performance ofoperational amplifiers has been experimentally evaluated. Specifically, the offset voltage of theoperational amplifiers in a follower topology has been evaluated when a conducted RF interferencefrom 10MHz to 1GHz is introduced into the non-inverter input at different temperatures. Theexperiments have been developed in two different commercial devices, the LM741 and the TL081.The results show that in both cases the offset voltage is reduced when the temperature is increased.Although a deeply investigation should be done in order to know the physical reason of this offsetreduction, the improvement of the non-linearity performance of transistor could be a reason.ACKNOWLEDGMENTThis work has been supported by the Spain-MINECO under Project TEC2010-18550 and AGAUR2009 SGR 1425.REFERENCES1. Ramdani, M., E. Sicard, A. Boyer, S. Ben Dhia, J. J. Whalen, T. H. Hubing, M. Coenen, andO. Wada, “The electromagnetic compatibility of integrated circuits-past, present and future,”IEEE Transactions on Electromagnetic Compatibility, Vol. 51, 78–100, Feb. 2009.2. EN IEC 62134-4, “Integrated circuits — Measurement of electromagnetic immunity, 150 kHzto 1GHz — Part 4: Direct RF power injection method,” 2006.3. Richelli, A., “Measurements of EMI susceptibility in ultra-low-voltage OpAmps,” Proc. of theEMC Compo., 13–17, Dubrovnik, Croatia, Nov. 2011.4. Gago, J., J. Balcells, D. Gonza´lez, M. Lamich, J. Mon, and A. Santolaria, “EMI susceptibilitymodel of signal conditioning circuits based on operational amplifiers,” IEEE Transactions onElectromagnetic Compatibility, Vol. 49, 849–859, Nov. 2007.

Impact of temperature on the electromagnetic susceptibility of operational amplifiers

In this paper, the impact of temperature on the electromagnetic susceptibility

of operational ampli¯ers at di®erent frequencies is presented. The IEC 62132-4 direct power

injection standard has been used with several commercials operational ampli¯ers in a printed

circuit board speci¯cally fabricated. The results show that the susceptibility of the operationals

ampli¯er is reduced with the temperature.Peer Reviewe

UPCommons

In this paper the impact of temperature on the electromagnetic susceptibility of operational amplifiers at different frequencies is presented. The IEC 62132-4 direct power injection standard has been used with several commercials operational amplifiers in a printed circuit board specifically fabricated. The results show that the susceptibility of the operationals amplifier is reduced with the temperature.Peer Reviewe

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Impact of temperature on the electromagnetic susceptibility of operational amplifiers

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