In this paper we introduce a CMOS low voltage/low power (LV/LP) voltage controlled oscillator (VCO). It includes a simple V-I converter, a current controlled ring oscillator based on new differential delay cells, and a source-coupled differential pair to convert differential signal to single-ended signal. The V-I converter is implemented as a source follower type, exhibiting excellent linearity of transconductance with low power consumption. The new delay cell employs local positive feedback to increase its DC gain, achieving stable oscillation at low supply voltage. The simulation and measurement results are given to show the linearity between the input (control voltage) and the output (frequency) in the frequency range of 100 MHz to 400 MHz with 1. 2 V power supply. The VCO only consumes power of 2.25 mW at operating frequency of 400 MHz and 1.2 V supply.