Abstract
This paper proposes a new method of constructing a compensation filter for the modulated wideband converter (MWC) system. The proposed method can be directly used in the MWC circuit without disconnecting any components. Furthermore, the non-ideal transfer characteristics of the real mixer output and the real ADC input are taken into account in the proposed compensation filter. The proposed method can be utilized in the advanced MWC that enables more flexibility in the design parameters of the MWC. This paper also demonstrates the reconstruction of the Bluetooth signal as a practical example for the evaluation of the reconstruction performance. The MWC successfully reconstructs the time-domain waveform of the signal based on the proposed compensation filter. Even in the case that the total effective number of channels in MWC is small as close to the necessary condition of the MWC, the error vector magnitude (EVM) was still under 1%, which is acceptable for Bluetooth device testing applications.
Highlights
E VERY human-made RF signals are often sparse in the allocated band
This paper proposes a new method to construct the compensation filter that can be directly used in the modulated wideband converter (MWC) system without disconnecting any components
In the 4-DPSK demodulation, these spurs do not affect the error vector magnitude (EVM) performance, because the 4-DPSK Bluetooth signal needs only 2 MHz bandwidth to achieve the maximum EVM performance. These results clearly demonstrate the capability of the MWC with the proposed compensation filter for the application of the communication device testing
Summary
E VERY human-made RF signals are often sparse in the allocated band. For example, in the wireless standard IEEE-802.11, allocated wideband signal is centered at the 2.4 GHz with several numbers of active bands depending on the surrounding users. We have proposed a new calibration method that estimates the actual sensing matrix coefficients of the MWC only with a single measurement based on a pilot multi-tone signal [40]. The number of measurements is reduced in this method, and the impact of the measurement-to-measurement timing fluctuations on the calibrated sensing matrix is fundamentally removed There is another factor that limits the reconstruction performance of the MWC. It is applicable only to basic MWC (q = 1), which makes the method not a good candidate in practical implementations This method needs many measurements, which takes a long time to build the compensation filter. In this paper, we explore a possibility of the MWC for capturing those real modulated signals to prove its feasibility in this area
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