Effects of conducted electromagnetic interference on analogue-to-digital converter

Abstract

The effects of conducted electromagnetic interference on an analogueto-digital converter (ADC) are presented by the measurement. The measurement results reveal that the DC shift behaviour of the output conversion is caused by the continuous-wave interference. The DC shift behaviour produces a novel failure criterion for the immunity measurement of the ADC.Introduction: Analogue-to-digital converters (ADCs) are used widely in closed loop control systems. The ADC affects the stability and control performance of the system directly. In the automotive field, the complex electromagnetic environment (EME) causes electromagnetic compatibility (EMC) problems of the ADC. The effects of the ADC in the presence of electromagnetic interference (EMI) need to be researched. Several works refer to immunity measurement and the immunity model of the ADC, which are introduced in [1, 2], but the models are only compared with the measurement immunity result and the output signal nonlinear distortion of the ADC is not easy to be modelled correctly. If the immunity measurement failure criterion is not well designed, the measurement result cannot reflect the actual behaviour of the ADC, and as a result the measurement result based models cannot work very well. Very little research relates to the analysis of the effects of electromagnetic interference on the ADC. This Letter focuses on the nonlinear distortion of the output signal of the ADC caused by an out-of-band interference. The DC shift phenomenon is detected, analysed and used to perform a novel failure criterion for the immunity measurement. The novel failure criterion based immunity measurement result reflects the accurate behaviour of the ADC in large bandwidth.

Electromagnetic interference detection method to increase the immunity of a microcontroller-based system in a complex electromagnetic environment

“…8, the immunity result of normal ADC1 is increased to a high level because of the RC LPF. The immunity result of detection ADC2 with an envelope detector almost keeps the same with the normal immunity result which is shown in [16]. Only at high-frequency from about 400 MHz to 1 GHz, the immunity result of the normal ADC1 is lower than the immunity of the detection ADC2.…”

“…The immunity result of the two ADCs with the EMI detector can also show the correctness of the method. The failure criterion is the DC shift failure criterion [16] with 5 LSB errors, as shown in Fig. 8, the immunity result of normal ADC1 is increased to a high level because of the RC LPF.…”

Improved Immunity Measurement of a Microcontroller to Conducted Continuous Wave Interference

“…In this case, the DC signal is always in bandwidth of the ADC, so the sinusoidal signal is the only consideration. The nonlinear distortion is a harmonic distortion which is particularly harmful because of DC shift, and DC shift is generated by the accumulation of an asymmetrically rectified signal, which is caused by the voltage clamp diode in this case [12]. The DC shift depends on the even-order nonlinear behavior (shown in Equation (2)), and DC shift is a DC effect which is very difficult to remove.…”

“…3.4. Vpp Failure Criterion [11][12][13][14] As shown in Figure 3, the output signal is a periodic signal, like sinusoidal waveform. In normal immunity measurement, the peak to peak amplitude of the output signal is compared with the reference signal to judge if the failure criterion is exceeded.…”