The differential coil is further optimized through a special coil layout as shown in Fig. 4.The middle tap of the coil is the outer winding in the layout. It is laid out wider to reduce the ohmic resistance of this winding, without any capacitive penalty as its capacitance is at common mode. This increases largely as the outer winding is the longest one. The inner windings are thinner, this decreases the capacitive load at the RF nodes of the oscillator increasing and the differential self-resonance frequency.