A fully integrated CMOS pulse transceiver with digital beam-formability for mm-wave active imaging is presented. The on-chip pulse transmitter of the transceiver includes an eight-element antenna array connected to eight pulse transmitters and a built-in relative pulse delay calibration system. The receiver employs a non-coherent detection method by using a FET direct-power detection circuit integrated with an antenna. The receiver dipole-patch antenna derives from the transmitter antenna but is modified with an on-chip DC-bias tail by shorting two arms of the dipole. The bandwidth of the receiver antenna with the DC-bias tail is designed to achieve 50.4-GHz in simulation and to cover the bandwidth of transmitter antennas. The output of the receiver antenna is connected to a resistive self-mixer followed by an on-chip low pass filter and then an amplifier stage. The built-in relative pulse delay calibration system is used to align the pulse delays of each transmitter array elements for the purpose of controlling the beam steering towards imaging objects. Both transmitter and receiver chips are fabricated in a 65-nm CMOS technology process. Measured pulse waveform of the receiver after relatively aligning all Tx's pulses is 0.91 mV (peak-peak) and 3-ns duration with a distance of 25mm between Rx and Tx. Beam steering angles are achieved in measurement by changing the digital delay code of antenna elements. Experimental results show that the proposed on-chip transceiver has an ability of digital transmitted-pulse calibration, controlling of beam-steeting, and pulse detection for active imaging applications.

This paper presents a 65-nm CMOS 8-antenna array transmitter operating in 117–130-GHz range for short range and portable millimeter-wave (mm-wave) active imaging applications. Each antenna element is a new on-chip antenna located on the top metal. By using on-chip transformer, pulse output of each resistor-less mm-wave pulse generators (PG) are sent to each integrated antenna. To adjust pulse delays for the purpose of pulse beam-forming, a 7-bit digitally programmable delay circuit (DPDC) is added to each of PGs. Moreover, in order to dynamically adjust pulse delays among eight SW's outputs, we implemented on-chip jitter and relative skew measuring circuit with 20-bit digital output to achieve cumulative distribution (CDF) and probability density (PDF) functions from which DPDC's input codes are decided to align eight antenna's output pulses. Two measured radiation peaks after relative skew alignment are obtained at (θ; φ) angles of (-56; 0) and (+57; 0). Measurement results shows that beam-forming angles of the fully integrated antenna array can be adjusted by digital input codes and by the on-chip skew adjustment circuit for active imaging applications.

A two-dimensional quasi-exact active imaging method for detecting the conducting objects buried in a dielectric half-space is proposed. In this imaging method, an image function which is a projection of buried object to an arbitrary direction, is introduced exactly by taking account of the presence of the planar boundary. The image function is synthesized from the scattering fields which are measured by moving a transmitting antenna (a current source) and a receiving antenna (an observation point) simultaneously along the ground surface. The scattering field is generated by the physical optics current assumed on the surface of buried object. Because the effectiveness of physical optics approximation has been confirmed for this problem, this is a quasi-exact active imaging method. The validity of this imaging method is confirmed by some numerical simulations and an experiment.