Design of a phase splitter for 3rd ISM band

This paper describes the design of a differential phase splitter, which is used as a RF building block for the 3rd Industrial Scientific and Medial (ISM) band (5.1-5.9 GHz) Wireless Local Area Network (WLAN). Utilizing the concept of RC feedback, the circuit achieves a 180 degree phase difference and gain balance, without sophisticated tuning or compensation methods. With the use of Cadence Spectre RF Simulator and the 0.18 μm CMOS Process Design Kit (PDK) from Chartered Semiconductor, the topology adopted in this paper is able to exhibit a gain of 2.93 dB to 3.57 dB within 5.1 GHz and 5.9 GHz. From a supply of 1.5 V, the circuit provides a phase error of 0.523 degree and a gain difference of 0.019 dB between its two output ports.