Improving the RF performance of 0.18 μm CMOS with deep n-well implantation

The radio-frequency (RF) figures of merit of 0.18 μm complementary metal-oxide-semiconductor (CMOS) technology are investigated by evaluating the unity-current-gain cutoff frequency (F
_T
) and maximum oscillation frequency (F
_max
). The device fabricated with an added deep n-well structure is shown to greatly enhance both the cutoff frequency and the maximum oscillation frequency, with negligible DC disturbance. Specifically, an 18% increase in F
_T
and 25% increase in F
_max
are achieved. Since the deep n-well implant can be easily adopted in a standard CMOS process, the approach appears to be very promising for future CMOS RF applications.