Author:
Hilmi Kayhan YILMAZ
Year:
2019
Abstract:
In this thesis, a tunable amplitude compensation method is presented for Hartley image-reject topology which eliminates amplitude errors causing degradation in image rejection performances. Firstly, different types of receiver topologies and solutions of these topologies for image signal problem are investigated as background knowledge. Especially, methods that need to be applied in these topologies to obtain sufficient image rejection ratios are studied for broadband systems. The presented solution of Hartley image reject topology for image signal problem is proven by mathematical expressions and supported by simulation results. The amplitude and phase errors of components used in the topology are identified. Also, the effects of these errors on image rejection ratios are investigated. In addition to the tunable amplitude compensation method for obtaining improvements of image rejection values, a non-tunable phase compensation method is also applied to the proposed design. The effects of the proposed tunable amplitude compensation method are measured on the designed receiver which covers 950-1450 MHz band. Improvement of image rejection values is presented. It is also shown that the necessity of filter banks could be eliminated by the proposed method. Besides, the frequency synthesizer is another critical part of the receiver design. Tunable reference clock frequency method is presented as a spur reduction method for spurious signals which are caused by using fractional-PLL in frequency synthesizer design. It is shown that tunable reference clock frequency is applicable for frequency spread spectrum systems which have 200 us guard time. Up to 40 dB spur reduction is achieved for LO signals which are required for 950-1450 MHz receiver. Superior results are obtained when considering the communication standards requirements in terms of phase noise and spurious power response. Measurement performed using both proposed methods are evaluated by a comparison with the literature and similar commercial products.