A 42.5–51.0 GHz SiGe BiCMOS Integrated Tunable Bandpass Filter and Attenuator

This paper presents a 42.5–51.0 GHz integrated tunable bandpass filter and attenuator; hereinafter referred to as a "filttenuator," which is implemented in a 130 nm SiGe BiCMOS process technology. The filttenuator utilizes a tunable bandpass filter with third-order coupled lines and high-Q tunable capacitive loads, a digital step attenuator with a zero-compensation technique, and a loss compensation amplifier to achieve precise amplitude control, tunable frequency, high attenuation range, sharp roll-off, and high rejection. This filttenuator achieves 38 dB worst-case stopband rejection, a sharp roll-off of 66 dB/octave, and a high attenuation range of 31.5 dB, with 1 dB effective steps. To the authors’ best knowledge, the presented filttenuator is the first tunable bandpass filter integrated with a digital step attenuator above 40 GHz demonstrated in silicon.