A Novel Concurrent 22–29/57–64-GHz Dual-Band CMOS Step Attenuator With Low Phase Variations

A novel 22-29/57-64-GHz concurrent dual-band CMOS 4-bit step attenuator with small phase variations is presented. A new integrated diplexer-attenuator possessing both attenuation and diplexer filtering functions is used to achieve the concurrent dual-band response for the 22-29/57-64-GHz concurrent dual-band attenuator, which leads to small size and low insertion loss. The 22-29/57-64-GHz concurrent dual-band attenuator also includes a new distributed attenuator configured to result in small phase variation. The 22-29/57-64-GHz concurrent dual-band attenuator is fabricated using a 0.18-μm BiCMOS technology. The measured insertion loss, root-meansquare (rms) amplitude error, and rms phase error are less than 7.9 dB, 0.55 dB, and 4.7° in the first passband of 22-29 GHz, respectively. In the second passband, 57-64 GHz, the measured insertion loss, rms amplitude error, and rms phase error are less than 11 dB, 1.5 dB, and 4.1°, respectively. The measured stopband rejections over the 16 states are greater than 28 and 31 dB at 12 and 36 GHz, respectively. The core chip size is 1.8 × 0.52 mm
²
.