Abstract
This article presents a frequency-modulated continuous wave (FMCW) harmonic radar in the 61-/122-GHz industrial, scientific, and medical (ISM) frequency bands. The radar is based on two self-designed monolithic microwave wave integrated circuits (MMICs) for the transceiver (TRX) and tag which are fabricated in a 130-nm SiGe BiCMOS technology. The presented TRX-MMIC consists of a fundamental voltage-controlled oscillator (VCO), a power amplifier (PA), Wilkinson power dividers, and a static divide-by-16 chain for stabilization within a phase-locked loop (PLL) in the transmitter (TX) part. The receiver (RX) part has two channels with a low noise amplifier (LNA), a Gilbert cell mixer, and an intermediate frequency (IF)-amplifier each. The fundamental of the VCO is converted by a frequency doubler and distributed to the local oscillator (LO) input of the RX-mixers. With such a TRX architecture the active nonlinear tag which consists of antennas, pre-amplifiers, and a frequency doubler can be detected. For a sweep from 60 to 64 GHz, a spatial resolution of 4 cm at 1-m distance and a range of 23.3 m is achieved. With these characteristics, the tag enables harmonic radar applications in the millimeter-wave (mm-wave) range for medium range with high accuracy and resolution with a small form factor.
Highlights
U NIQUELY identifying the intended target can be a challenging task for conventional frequency-modulated continuous wave (FMCW) radar in an environment with heavy clutter
The power-added efficiency (PAE) was not the main concern during the design of this circuit and as a result low since all stages are biased in the linear region for higher gain
We presented a highly integrated 61-/122-GHz harmonic radar system based on an active frequency doubler tag in a 130-nm-BiCMOS SiGe:C technology
Summary
U NIQUELY identifying the intended target can be a challenging task for conventional frequency-modulated continuous wave (FMCW) radar in an environment with heavy clutter. Compact and passive tags are attached to insects or other animals with a small RCS the nonlinear tag is distinguishable from the clutter of foliage These systems are mostly designed below the millimeter-wave (mm-wave) frequency range where higher output power and lower free-space path loss (FSPL) are achievable. With the active tag, which adds sufficient gain to the power transfer equation in order to detect the target with a high signal-to-noise ratio (SNR) at medium distances, high absolute bandwidth for high range resolution and accuracy is achievable. The novelty of an integrated TRX (see Fig. 1) should be noted, which we use to carry out the free space measurements in this article Such a compact transceiver and tag realizations as presented here can enable many applications for harmonic radar.
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