This paper firstly presents a CMOS voltage-controlled oscillator (VCO) which enables octa-phase triangular waveform generation. By utilizing a cascaded relaxation oscillator core followed by a pseudo injection-locked oscillator circuit, an octa-phase differential VCO with triangular waveform outputs is realized. Simulation results show that the proposed fully differential multi-phase VCO can achieve broad tuning range with programmable timing capacitors, offering <1% phase mismatch.