A millimeter-wave 0.18-μm BiCMOS sub-nanosecond pulse-generator with extremely low RF leakage

An ultra-low-leakage RF pulse generator capable of producing very narrow RF pulses with small rising and falling time for short-range high-resolution radar and high-data-rate communication systems is developed using 0.18-μm BiCMOS technology. The RF pulse generator exhibits an extremely-low RF leakage implementing the RF leaking suppression technique, in which the RF leaking signal is cancelled by combining with its replica using an active balun. In addition, the active balun also amplifies the gated RF pulses hence providing gain for the RF pulse generator. A graphical analysis based on the insertion loss and isolation contours, enabling selection of the optimum sizes for transistors in the series-shunt switches, is also presented. From 31 to 37.1 GHz, the designed RF pulse generator exhibits -1.9 dB (loss) to 1.1 dB (gain) and 14.5-30 dB input return loss. The output return loss is higher than 10 dB from 33 to 35.9 GHz. From 30 to 40 GHz, the isolation is higher than 40 dB and, especially at 34 GHz, the isolation reaches 70 dB. The rising and falling times were measured as 136 ps and 70 ps, respectively. Very narrow RF pulses of 200 ps have been generated. The RF pulse generator consumes a 7.3 mA from a 1.8-V power supply and occupies a chip area of 0.225 mm².