Electromagnetic impulse radio camera

Abstract

An UWB impulse radio programmable transmitter array is presented, usable for electromagnetic beamforming. The linear antenna array may be programmed for focal beamforming using seven impulse radio transmitters. Two different spatial configurations are evaluated for use as beam scanning electronics of an electromagnetic camera. A novel high-precision, programmable delay element is explored for accurate beam control. Measured results shows that the scan line of the beamformer can be steered with sufficient resolution facilitating an electromagnetic CMOS camera.

High precision calibrated digital delay element

“…Adding production spread of up to 20% due to mismatch, digital gate delays do not provide sufficient resolution nor precision. We have previously published a simple, digital tuning technique using back-gate biasing [6,7] enabling digital tuning of single inverters by a few picoseconds. In this Letter, we characterise delay elements by using a ring oscillator-based calibration circuit with a precision of a few picoseconds to compensate for process variations and device mismatch.…”

“…1. A digitally programmable fine-tuning delay line with 65 settings facilitates adjustment up to approximately 500 ps in steps of 7 -8 ps [6,7]. It has an absolute delay of about 2 ns, but this is not a problem since the same delay is added to all the Tx-antennas in the array.…”

“…The programmable delay line is a cascade of 64 dual-inverter buffers. In each of these dual inverters, the bulk voltage of the PMOS transistor in one of the inverters is switched between two values in order to gain the fine delay tuning [6,7].…”