# A Novel Active Polyphase Filter Employing Frequency-Dependent Image Rejection Enhancement Technique
## 5 Comparative Analysis of Simulation and Measurement Results
In addition, the bandwidth is also an important parameter of the image rejection filter; the selection of the center frequency largely determines the value of the operating bandwidth. The higher the center frequency, the larger the bandwidth. The value of the operating bandwidth is also related to the number of stages. By setting the center frequency of each stage appropriately, the operating bandwidth of the image rejection filter can be effectively expanded. As a key part of the receiver chip, the power consumption, area, OIP3, gain, and IRN of the image rejection filter also have a significant impact on the receiver system. The proposed APPF has a better IRR and a smaller number of stages compared to other works using more advanced process, which can also be visualized from IRR per stage. The significantly larger operating bandwidths of [13; 18] compared to the other works are due to the fact that their center frequencies are chosen at several GHz. The proposed design has an advantage in terms of operating bandwidth with similar center frequencies. Meanwhile, the proposed APPF can work in a higher operating frequency range compared to other active complex filter schemes [17; 24]. In terms of power consumption and area, RC-PPFs [18; 21] occupy a larger on-chip area and require energy-consuming buffers with good driving capabilities to assist them, although they do not have static power consumption. In the active image rejection filter, the power consumption and area depend mainly on the \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Parameter** & **2020 [18]** & **2020 [21]** & **2020 [13]** & **2023 [17]** & **2005 [24]** & **This Work** \\ \hline Process & 90 nm & 65 nm & 65 nm & 22 nm & 250 nm & 180 nm \\  & CMOS & CMOS & CMOS & FD-SOI & CMOS & CMOS \\ Type & RC-PPF & RC-PPF & Active-RC & CBPF & APPF & APPF \\ Number of stages & 3 & 2 & 2 (2) & 1 & 4 & 1 & 2 (2) \\ Total IRR (dB) & \(-30\) & \(-40\) (1) & \(-40\) (2) & \(-27\) & \(-48\) & \(-31\) & \(-53.4\) (2) \\ IRR per stage (dB) & \(-10\) & \(-20\) (1) & \(-20\) (2) & \(-27\) & \(-12\) & \(-31\) & \(-26.7\) (2) \\ Bandwidth/Center & 1850/1580 & 20/200 & 2000/3000 & 5/60 & 23.9/18.1 & 10/100 & 26/110 (2) \\ Power (mW) & N/A & N/A & 15 (2)(3) & 0.099 & 11 & 1.5 & 2.98 (2) \\ Core area (mm\({}^{2}\)) & 0.25 & 0.19 & 0.0091 (2) & 0.0049 & 0.95 & 0.051 & 0.081 (2) \\ OIP3 (dBm) & N/A & \(-6.0\) (1) & 5.8 (2) & 3.4 (1) & 14.6 (1) & 0.9 & \(-1.55\) (2) \\ Gain (dB) & \(-14.3\) & N/A & 14 (2)(3) & 13.6 & 6.6 & 3.53 & 6.68 (2) \\ IRN (\(\mu\)V) & N/A & N/A & N/A & 107.7 & 78.1 & 37.4 & 58.6 (3) \\ \hline \hline \end{tabular} \({}^{(1)}\) Deduced parameter. \({}^{(2)}\) Simulation result. \({}^{(3)}\) With I/Q mixer and buffer.  
\end{table} 
Table 2: Performance summary and comparison. manufacturing process, supply voltage, and number of stages. Therefore, the proposed work has moderate parameters. With respect to the OIP3 parameters, the proposed design performs generally well and basically satisfies the application requirements of circuits such as the ADC in the wireless system. In addition, the two performance parameters of gain and IRN of the proposed design also perform at relatively excellent levels compared to other works. Compared to the active image rejection filter scheme, RC-PPFs [18; 21] have not only no gain but also insertion loss. In summary, the proposed APPF shows better image rejection and excellent overall performance.