We present a two-stage OPCPA system based on a Ti:sapphire seed and a thin-disk regenerative amplifier producing compressed pulse energies of more than 3 μJ and durations of less than 6 fs at a high repetition rate of 143 kHz. In combination with the obtained CEP stability and the repetition rate scalability between 100 and 500 kHz the system forms an ideal tool for high field and phase sensitive spectroscopic experiments.