A low cost SiGe based extension unit for ultra wideband sensing system

The well-known advantages of Silicon-Germanium bipolar technology, like low cost, small size, or high integrability, have recently been expanded to highest-frequency applications. The article presents a direct-conversion extension unit for ECC compliant PN-sequence based ultra-wideband sensing system that operates in the 6-8GHz band which is also easy reconfigurable in order to match the Federal Communications Commission frequency band. The extension unit consists of the application specific Integrated Circuit (IC) considered as its core element, than the experimental IC carrier with deployed delay line for 90 degree phase shifting of the 7GHz LO signal and the appropriate LTCC band-pass and low-pass filters. The IC which is designed and realized in 0.35μm SiGe technology from AMS utilizes optimized ultra-wideband mixer pair. Aside from that, the IC is equipped with 50Ω matched wide-band differential amplifiers, which are intended to operate as active BalUns. The mixers are based on conventional double-balanced Gilbert cell topology in order to provide required conversion gain, signal isolation and dynamic range over the target frequency band. The measured conversion gain of the mixer is 6dB, the single- sideband noise figure at 50MHz is 15dB and the input-referred 1dB compression point over the band of interest is -11dBm. The size of the chip is 1950μm × 850μm. The IC was designed for a supply voltage of -3.3V and draws 34mA.