A photonics-based frequency mixer for up converting an IF signal into an RF signal with very large suppression in the carrier and the sideband is presented. The mixer is filter free and has a simple structure. It enables off-the-shelf bias controllers to be incorporated into the system. This solves the problem of the carrier and sideband suppression reduces with time that is present in all reported photonics-based single sideband mixers. Experiments are conducted to verify the proposed mixer structure. Results show the single sideband mixer generates an up converted RF signal with more than 40 dB suppression in the carrier and sideband over a wide frequency range. This is a 10-dB improvement compared to the reported structures. A conversion efficiency of around -6 dB is attained, which is over 10 dB higher than the reported structures. Frequency up conversion of an IF signal with a band of frequency and a long-term stable performance are also demonstrated.