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This paper presents a W-band 2 × 2 focal-plane array (FPA) for passive millimeter-wave imaging in a standard 0.18 μm SiGe BiCMOS process (fT/fmax = 200/180 GHz). The FPA incorporates four Dicke-type receivers representing four imaging pixels. Each receiver employs the direct-conversion architecture consisting of an on-chip slot folded dipole antenna, an SPDT switch, a low noise amplifier, a single-balanced mixer, an injection-locked frequency tripler (ILFT), an IF variable gain amplifier, a power detector, an active bandpass filter and a synchronous demodulator. The LO signal is generated by a shared Ka-band PLL and distributed symmetrically to four local ILFTs. The measured LO phase noise is -93 dBc/Hz at 1 MHz offset from the 96 GHz carrier. This imaging receiver (without antenna) achieves a measured average responsivity and noise equivalent power of 285 MV/W and 8.1 fW/Hz1/2, respectively, across the 86-106 GHz bandwidth, which results a calculated NETD of 0.48 K with a 30 ms integration time. The system NETD increases to 3 K with on-chip antenna due to its low efficiency at W-band. MMW images have been generated in transmission mode. This work demonstrates the highest integration level of any silicon-based systems in the 94 GHz imaging band.
Date of Publication: Oct. 2012