Semi-analytical computation of error vector magnitude for UMTS SAW filters

Error Vector Magnitude (EVM) is a key parameter for the design of digitally modulated communication systems. In the case of SAW filters, it is a measure for the caused inter-symbol- or inter- chip. interference. It can be mainly attributed to linear distortion. This paper wilt present a semi-analytical method for computing EVM based on the definition given in [1]. The major goal of this work was to provide a precise, easy-to-use and computationally efficient method to obtain EVM for UNITS SAW filters while avoiding discrete time system simulation or the use of special measurement equipment other than network analyzers. Therefore, time- and frequency domain formulas for EVM were derived without making simplifying assumptions or approximations. Because the former requires FFT to obtain the filter impulse response from a measured or simulated transfer function and the latter involves numerical integration, this method is called semi-analytical. Numerical results based on the time-domain EVM formula will be compared to results from EVM measurement.