This paper presents a novel approach to control wavefronts in planar optics using frequency-synthesized phase engineering. The authors propose a method to encode different spatial phases to separate frequencies, enabling arbitrary dispersion tailoring and frequency-separated functionalization. Cholesteric liquid crystal (CLC) is used as a birefringent medium due to its frequency-selective geometric phase encoding. By locally presetting the initial orientation of CLC, geometric phases are encoded into the reflected light. The proposed strategy is demonstrated through cascading CLC layers with specifically designed helical pitches and initial director orientations. This results in planar lenses with RGB achromatic, enhanced chromatic aberration, and color routing properties. The lenses achieve high focusing efficiency (85.3% for selective spin) and low crosstalk among colors, making them suitable for various applications such as imaging, computing, and communication. The work opens new possibilities for functional planar optics and enhances the performance of existing optical apparatuses.This paper presents a novel approach to control wavefronts in planar optics using frequency-synthesized phase engineering. The authors propose a method to encode different spatial phases to separate frequencies, enabling arbitrary dispersion tailoring and frequency-separated functionalization. Cholesteric liquid crystal (CLC) is used as a birefringent medium due to its frequency-selective geometric phase encoding. By locally presetting the initial orientation of CLC, geometric phases are encoded into the reflected light. The proposed strategy is demonstrated through cascading CLC layers with specifically designed helical pitches and initial director orientations. This results in planar lenses with RGB achromatic, enhanced chromatic aberration, and color routing properties. The lenses achieve high focusing efficiency (85.3% for selective spin) and low crosstalk among colors, making them suitable for various applications such as imaging, computing, and communication. The work opens new possibilities for functional planar optics and enhances the performance of existing optical apparatuses.