AbstractsEngineering

Frequency up-conversion is an integral part of the (sub)mm wave integrated radar system that is currently developed at the TUDelft in the context of the MEMPIS program. The proposed up-converter IC allows the necessary signal modulation for the radar to be generated at a relative low frequency, after up-conversion to W-band takes place. In our case, the FMCW (frequency modulated continuous wave) principle is used for the actual radar operation. This up-conversion, based on analogue signal multiplication, reduces the source signal bandwidth requirement by the amount of its multiplication factor. The purpose of this work is to explore the possibility of implementing a wideband high-order frequency up-converter which suits the needs of our radar system namely, like high conversion gain, spur suppression, improved noise performance, as well as limited DC power consumption. In our system, the up-converter converts an input signal from X and Ku-band (around 10GHz) to W-band (around 94GHz). The up-converted signal is used to drive both the transmitter antenna and the receiver mixer LO port. The whole circuit includes a multiply by 8 chain and necessary gain blocks on W-band. Study of the frequency multiplication process has resulted in a carefully planned frequency allocation, as well as, power leveling for each sub-circuit. A wideband frequency doubler capable of high conversion gain and low unwanted spur generation is designed. In the multiply by 8 chain, optimum operation of the frequency doubler, as well as, on chip filtering are performed to guarantee the spectrum purity of the output signal over wide bandwidth. Two W-band medium power amplifiers are optimized for flat gain frequency response. The multiply by 8 chain provides an output signal from 80GHz to 112GHz, with an in-band conversion gain ranging from 13.2 dB to 16.6dB. The suppression of unwanted spurs is better than -40dB. The antenna driver amplifier delivers more than 3dBm output power with 3dB in-band gain variation. The LO driver amplifier delivers more than 150mV peak voltage swing at mixer LO port with less than 2dB in-band gain variation.