Tunable delay compensation circuit in polar loop transmitter for WiMAX applications

In this paper, a time delay circuit is designed for path mismatch compensation in the polar loop transmitter for the WiMAX standard. The delay circuit contains two stages, each realized in the second-order form of the Padé approximant, to account for a tuning range from 1 ns to 10 ns in 1 ns steps. The proposed circuit is fabricated using 0.35-μm SiGe technology in order to be incorporated into a fully integrated transmitter in the future. The measurement result in network analyzer shows the delay dispersion in worst case within 30 MHz signal bandwidth has 7% variation and has gain dispersion 1.4 dB.