Test time reduction for ACPR measurement of wireless transceivers using periodic bit-stream sequences

In this paper, we propose a novel algorithm for measuring ACPR of integrated wireless transceivers. This is an important specification to measure as it determines the amount of "interference" created by the transmitting system in adjacent channels while transmitting data in a specific channel. Current industry testing algorithms use pseudo-random bitstream as input stimulus to test the RF power amplifier (PA) in the transmission system. For a pseudo-random bitstream, the spectral energy is distributed over the whole spectrum of interest. Hence, for ACPR computation, a large number of frequency components over a wide range, needs to be measured. In this paper, by using a periodic bitstream instead, where the energy is concentrated at much fewer numbers of frequencies, ACPR is measured. This requires less number of measurements to be made and hence, the test time is reduced considerably. The periodic bit-sequence that provides the most accurate ACPR measurement is obtained through an alternate test generation algorithm. Our test generation algorithm employs a set of non-linear regression equations to compute the ACPR of the transmitter system from the output spectrum of the PA. Studies showed that the test time can be reduced considerably by changing the number of periods of the optimum bit-sequence. The number of measurements on the output was reduced by a factor greater than 2. Overall, in the proposed approach, over an order of magnitude reduction in test time was achieved, while the ACPR was measured within an accuracy of /spl plusmn/0.2% of the actual value.