tailieunhanh - Mobile and Wireless Communications Network layer and circuit level design 2012 Part 9

Tham khảo tài liệu 'mobile and wireless communications network layer and circuit level design 2012 part 9', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Polyphase Filter Design Methodology for Wireless communication Applications 231 and values of resistors composing the filter allowing the required IRR. To investigate this further shows the simulated IRR results for different polyphase networks with mismatch consideration. The IRR is illustrated in three-dimensional plot as a function of the resistor s electrical value R and resistor size which for the current study corresponds to the width W . In the X-axis the parameter R is used to calibrate the first stage of the polyphase filter. The resistor values of the other stages are set to a fixed pole ratio a as shown in 14 . The capacitors are chosen to give the right pole frequency. These three-dimensional plots show first that multiplying the number of stages gives a higher IRR. For example for the couple R W equal to 700 10pm the IRR increases from 52dB with three-stage polyphase design a to 60dB with four stages b and reaches 65dB with five stages c . However having many stages in the polyphase network conducts to a growth of the components number and increases the silicon area the power loss and the parasitic capacitances. Hence according to the costumer need designers should make a compromise between achieving a polyphase filter with high image rejection and low area and low silicon area cost. Furthermore illustrates that a high IRR is achieved if the value and the size of the resistor converge to the optimal values on each multi-stage polyphase filter. For about the different filter configurations it shows that the IRR variation versus R corresponding to a given configuration is quasi-linear. For instance for a five-stage PPF the IRR changes from 65dB to 68dB and 70dB for resistor s width of 10pm 20pm and 40pm respectively c . In this case it can be noted that a gain of only 5dB in the IRR produces an expansion of the resistor size by almost 400 confirming the existence of an optimal component sizing for a specified IRR