A compact ku-band 6-bit attenuator in 0.35um SiGe BiCMOS technology

This paper presents a compact 14–18 GHz 6-bit attenuator in 0.35-μm SiGe BiCMOS technology. To realize size miniaturization, large attenuation range and low insertion loss, the switched Pi/T attenuator topology is employed. It adopts serial and shunt single-pole-single-throw switches merged with a resistive network to control attenuation accurately. In addition, the proposed attenuators use a novel inductive low-pass filter for phase correction to compensate the phase error in difference states. The designed prototype achieves an attenuation range of 31.5 dB in a 0.5-dB step size with 64 states, average insertion loss of 8±0.6 dB, P1dB of better than 10 dBm, input/output return losses of better than −10/-11 dB in all states, and chip size of 0.80×0.34 mm2 only excluding testing pads. The calculated root-mean-square (rms) amplitude error is less than 0.29 dB, with rms phase error is less than 3.9o in the designed frequency range.