Above-complementary metal-oxide-semiconductor inductor for rapid prototyping of mixed-signal system on chips

A new prototyping method for a radio frequency system on a chip (SoC) using above-complementary metal-oxide-semiconductor (CMOS) inductors is proposed. In this method, a spiral inductor is formed on a CMOS chip fabricated and diced by normal manufacturing processes. Since the fabrication of above-CMOS inductors is carried out in a chip-by-chip manner with simple processes, the flexible adjustment of inductance and the evaluation of chip performance can be carried out within a short turnaround time. Therefore, the rapid prototyping of mixed-signal SoCs can be realized. This technique can be understood as a realization of a "breadboard on a chip" since it is based on the experimental method on a cut-and-try basis. We have successfully fabricated above-CMOS inductors with different inductances on different CMOS chips of the same design. The adjustment of the oscillation frequency of a voltage-controlled oscillator and the impedance matching of a low-noise amplifier have also been demonstrated.