Highly Selective Bandpass Switch Block With Applications of MMIC SPDT Switch and Switched Filter Bank
Di Lu, Junbo Liu, Ming Yu
Abstract
A new bandpass single-pole single-throw (SPST) switch (BPSW) is proposed in this letter. The proposed BPSW configuration can be directly employed as a building block to construct the single-pole N-throw (SPNT) switch or the highly-selective switched filter bank with no need for the extra control circuit, thus effectively reducing the circuit size and lowering the loss. The operation mechanism of the BPSW is analyzed, and the filter-synthesis-based design method is given. For demonstration, 3-6 GHz and 4-8 GHz BPSW blocks are built using the commercial GaAs pHEMT process to construct the single-pole double-throw (SPDT) switch as well as the two-way integrated switched filter bank. The filter bank is implemented in 0.25 μm GaAs pHEMT process. Two passbands are measured at 2.7-5.79 GHz and 3.72-7.35 GHz with a minimum insertion loss of 2.7 dB, while the all-OFF state can be set with over 35 dB suppression. The measurement results are in good agreement with the simulation that verifies the concept.