In order to develop precision vertex detectors for the future linear collider, fast active monolithic active pixel sensors are studied. Standard CMOS 0.25 mum digital process is used to design a test chip which includes different pixel types, column-level discriminators and a digital control part. In-pixel amplification is implemented together with double sampling. Different charge-to-voltage conversion factors were obtained using amplifiers with different gains or diode sizes. Pixel architectures with DC and AC coupling to charge sensing element were proposed. As far, hits from conversion of 35Fe photons were registered for the DC-coupled pixel. Double sampling is functional and allows almost a complete cancellation if fixed pattern noise.