A 0.25-μm Si-Ge fully integrated pulse transmitter with on-chip loop antenna array towards beam-formability for millimeter-wave active imaging

This paper presents a 100-120-GHz pulse transmitter chip with a 54 × 24 on-chip loop antenna array for the purpose of beamformability in portable millimeter-wave (mm-wave) active imaging applications. We present a new idea for silicon-based mm-wave pulse beamforming by using voltage-varied CMOS inverter chain. This 4-mm×4-mm transmitter chip is designed and fabricated in a 2.5-V 0.25-μm 4-metallayer Si-Ge Bi-CMOS process. The 30-μm × 30-μm loop antenna located on the top-metal layer operates as an coil in an integrated mmwave pulse generator. Each of on-chip pulse generators employing underdamped/ over-damped conditions to produce mm-wave pulses includes an R-L-C circuit, a bipolar junction transistor (BJT) operated as a switch and a CMOS inverter chain circuit for shaping the rising edge of the input clock. Simulation results by ADS 2009 and HSPICE show that loop antenna' inductance and resistance at 80-120-GHz are 51 pH and 3Ω, respectively. A simulation performance of an integrated 13 × 6 loop antenna array illustrates the variation of maximum radiation angles depending on different phase values between array's elements. By using an mm-wave power meter, a 90-140-GHz standard horn antenna and a Schottky diode detector, several measured radiation patterns of this loop antenna array chip are achieved. From the measurement result, we demonstrate the possibility of an integrated mm-wave pulse generator for the purpose of beam-forming by changing power supplies of inverter chains.