Communication systems rely on stable VCO (voltage controlled oscillator) to maintain phase-locked conditions and ensure transmitted data integrity. Many third and later generation systems require multi-mode or multi-band signal sources (VCOs) to cover their bandwidth requirement. This paper presents the design of a dual-mode oscillator that simultaneously generates two signals at different frequencies. The novel approach is based on multi-mode frequency generation technique without recurring the switched inductors and varactors networks, and also support improved phase noise performance for a dual-mode operation over the band. The measured phase noise for mode #1 (450-900 MHz) and mode #2 (900-1800 MHz) are typically -120 dBc/Hz, and -112 dBc/Hz at 10 kHz offset from the carrier frequency respectively; and to our knowledge, this is the best phase noise performance for this class of VCO by using planar CMR (coupled microstripline resonator) so far reported.