A $\pi$-type Variable Attenuator with Low Phase Shift
Ung-Hee Park, Gil‐Cho Ahn · The Journal of the Korean Institute of Information and Communication Engineering · 2009
A voltage controlled attenuator using a PIN diode and two resistors of the -type fixed attenuator is described in this paper. The proposed variable attenuator operating for a fixed attenuation range has a good input VSWR and a low intermodulation signal. For the low phase shift, a PIN diode is connected with open stub for the purpose of phase compensation. The stub for phase compensation is calculated by the Deloach method and the related circuit theory. This attenuator is easily fabricated on the microstrip and can be normally used in fine control circuits within small attenuation range. The fabricated attenuator for 2110~2170 MHz frequency band has about 4 dB of an attenuation range, of phase variance, and -20 dB of S11 according to the input voltage from 0 to 2.7 V.