Multi Color Lens Coupled SiGe HBT Chip Set

This paper presents the concept and implementation of an active all-electronicterahertz multi-color imager with the functionality demonstrated in the frequency range of 160 GHz–1 THz. The proposed terahertz system is realized in the form of two independent highly integrated low-cost transmitter (Tx) and receiver (Rx) modules. Each module consists of a single silicon die with a silicon lens-coupled ultra-wideband on-chip antenna and is assembled onto a low-cost FR-4 printed circuit board using traditional wire-bonding.

The chip-set is implemented in a ${hbox{0.25}}~mu{hbox {m}}$ SiGe HBT BiCMOS process with $f_{T}/f_{max}$ of 280/435 GHz. The main Tx path is composed of an antenna-coupled harmonic generator and is driven by a$times $ 9 multiplier chain fed from an external reference signal centered around 17–18 GHz. Four identical Tx paths are spatially combined on a single chip to increase the output power. The Rx chip shows a 2 $times$ 2 arrangement of identical antenna-coupled broadband sub-harmonic mixers driven by a single $times $ 9 multiplier chain; similar to that from the Tx circuit. The system operates simultaneously at six harmonics being multiple numbers of 165 GHz. The signal-to-noise ratio in transmission-mode active imaging with a 1-Hz resolution bandwidth is 90 dB for 165-GHz band, 115 dB for 330- and 495-GHz bands, 95 dB for 660- and 820-GHz bands, and 70 dB for 990-GHz band.