u2225 r bias and its value is large since both r s1 off and rbias are large when the en_cap signal 1 the capacitor 706 is used to form the lc tank resonance frequency at the same time rbias 708 is parallel to an on resistance of switch 713 these parallel resistances form the series equivalent r for each of the capacitor branches when en_cap 1 since the on resistance of switch 713 is small few u03c9 u2212 100 s u03c9 it dominates the value of the series equivalent r presenting a low impedance to gnd for the capacitor 706 of the capacitor array 702 effectively this makes the capacitor 706 of the capacitor array 702 part of the lc tank 702 712 the reason for pulling rbias 708 to vdd gt 1 4v during en_cap 0 is to prevent the negative swing of node a from turning on the diode of the pn junction of switch 713 by ensuring this pn junction is off distortion in the signal is mitigated hence the harmonic distortion of the power amplifier due to the pn junction is prevented hence for higher frequency operation a smaller number of capacitors 706 are required from capacitor array 702 and more rbias 708 branches are connected resulting in a smaller equivalent parallel resistance r pc to the lc tank 702 712 hence lower q at higher frequency operation similarly for lower frequency operation a larger number of branches of capacitors 706 are required from capacitor array 706 and less rbias 708 branches are connected resulting in a larger equivalent parallel resistance r pc to the lc tank hence higher q at lower frequency operation the rbias 708 of each branch can.