High Self-Resonant and Area Efficient Monolithic Transformer Using Novel Intercoil-Crossing Structure for Silicon RFIC

Novel on-chip multiport symmetrical transformer that has high self-resonant frequency and good area efficiency is presented. This technique involves the unique way of intercrossing the transformer's primary and secondary coil using multiple metallization layers. A stacked transformer, with the same area utilization as the proposed device, is selected for performance comparison. The proposed design has demonstrated a higher self-resonant frequency in differential transmission line transformer configuration, i.e.,
f

<sub>d

-

SRF(Stacked)</sub>
= 8 GHz and
f

<sub>d

-

SRF(Sym)</sub>
= 10.35 GHz. The structure presented is fully compatible with standard CMOS foundry processes. The silicon data reported in this letter are based on Chartered Semiconductor Manufacturing's 0.13-
mu
m RFCMOS technology node.