Study on Packaging of a Wideband Filtering Out-of-Phase Power Divider Based on Multi-Layer Stacked Striplines

This paper presents a compact design method for out-of-phase power divider with wideband filtering response and high isolation based on multi-layer stacked striplines. By modifying the input transmission line (TL) in a traditional Marchand balun as a one-wavelength
$(\lambda_{\mathrm{g}})$
short-circuited one, out-of-phase power division with a three-pole high selective filtering response is obtained. Based on the advantages of stripline, broadside coupling is adopted so that required coupling strength for wideband performance can be achieved. Then, a grounded resistor is loaded via a
$\lambda_{\mathrm{g}}/2$
TL between two output ports, leading to a high isolation over the wide passband. Finally, an example circuit centered at 2 GHz is designed by utilizing multi-layer printed circuit board (PCB) and packaged by multiple screws. The realized circuit size is only about
$0.14\lambda_{\mathrm{g}}\times 0.13\lambda_{\mathrm{g}}\times 0.02\lambda_{\mathrm{g}}\text{mm}^{3}s$
. To verify the reliability of proposed packaging design method, both simulated and measured results are displayed and good agreement in the working passband is found.