A phase-correlated duo-binary waveform generation technique for millimeter-wave radar pulses

We propose a technique for generating millimeter-wave radar waveforms using edge-triggered pulse generator circuits. By synchronizing the chip rate to the oscillation frequency of a binary control signal, a phase shift is introduced in the generated pulses. This way, the millimeter-wave signal can be phase-modulated without the need of additional circuit elements. We show that high-resolution radar waveforms with low range side lobes can be generated with this technique. Using brute-force optimization, we evaluate all possible sequences up to a sequence length of 25 chips and identify optimal waveforms for each length. Optimal sequences with the energy centered at zero delay and side lobes not exceeding unity are presented. The optimized waveforms are measured and verified using an in-house resonant tunneling diode (RTD) metal-oxide-semiconductor field-effect transistor (MOSFET) pulse generator. The matched filter response of the optimal waveforms is reproduced closely in the measurements. The results enable increased sensitivity in radar systems using coherent millimeter-wave pulse generators for low power applications, as for instance, radar gesture recognition in handheld devices. Using pulsed millimeter-wave radar systems with low duty cycles, continuously running oscillators can be avoided and systems with ultra-low power consumption are possible.