Silicon microring resonator modulators are versatile active on-chip devices capable of high-speed modulation with low energy consumption. However, the effects of PN junction alignment variance for different doping concentrations during fabrication have not been looked into. In this work, we numerically demonstrate and analyse the optimisation of the silicon microring resonator modulator based on the carrier depletion mechanism for high extinction ratio and low energy consumption at the communication wavelength of 1550 nm. A range of carrier doping concentrations and offset of the PN junction to the waveguide centre can be used to optimise the modulation efficiency, energy consumption and insertion losses of the microring modulator. In particular, the effects of the offset of the PN junction are analysed for three cases in the carrier-depletion silicon phase shifter: (i) p-type doping < n-type doping, (ii) p-type doping = n-type doping, and (iii) p-type doping > n-type doping. Subsequently, three types of microring ring modulator architecture – the all-pass microring resonator, the add-drop microring resonator, and the all-pass dual uncoupled microring resonator – are realised and analysed. Our results suggests that doping concentration between 2 × 1017 cm-3 to 5 × 1017 cm-3, with the p-doping concentration lower than the n-doping concentration, should be employed in order to achieve a tunability of > 16 pm/V and extinction ratio of > 8 dB.