Image-Band Interference Cancellation for Multi-Mode/Band Receivers with Baseband AGC

A novel method is proposed in this paper to cancel the image-band interference for multi-mode/band receivers with baseband AGC. The Hilbert transformer, which plays an important part in heterodyne multi-mode receivers described here, has the imperfection which results in image-band interference in baseband, causing severe deterioration of transmission performance. The method proposed here cancels the image-band interference by estimating and canceling imperfection of the analog Hilbert transformer consisting of the phase error and the amplitude error by correlation matrices calculation. Furthermore, filtering is employed here to improve the estimation accuracy. This paper also shows the error estimation performance of the proposed method and the BER performance of the interference cancellation by computer simulation under the circumstance of CIR =-20 dB, and compares them with that of the conventional method.