The RFE is an integrated transceiver circuit for the 122-GHz ISM band with antennas in package. It includes a low-noise amplifier (LNA), quadrature mixers, a poly-phase filter, a voltage-controlled oscillator, divide-by-32 outputs and transmit and receive antennas (see Figure 1). The RF signal from the oscillator is directed to the RX path via buffer circuits. The RX signal is amplified by the LNA and converted to baseband by two mixers with quadrature local oscillator (LO). The 120-GHz LO has four analog tuning inputs with different tuning ranges and tuning slopes. The tuning inputs can be combined to obtain a wide frequency tuning range. The analog tuning inputs together with integrated frequency divider and external fractional-N PLL can be used for frequency modulated continuous wave (FMCW) radar operation. With fixed oscillator frequency it can be used in continuous wave (CW) mode. Other modulation schemes are possible as well by utilizing analog tuning inputs.
The IC is fabricated in a SiGe BiCMOS technology.
The main field of application for the 120-GHz transceiver radar frontend is in short range radar systems with a range up to about 10 meters. By using dielectric lenses or reflectors, the range can be increased considerably. The RFE can be used in FMCW mode as well as in CW mode. Although the chip is intended for use in the ISM band 122 GHz – 123 GHz, it is also possible to extend the bandwidth to the full tuning range of 6 GHz.