An apparatus is presented for generating a true random number generator (TRNG). The apparatus includes a magnetic tunnel junction (MTJ) device including a first layer, a second layer, and third layer, as well as a bias circuit to bias the MTJ device along with a pulse height discriminator and a time-to-amplitude convertor to generate random bit-streams. The second layer is a barrier layer with an energy barrier height in the order of 20kT, where k is the Boltzmann constant and T is the absolute temperature. Random flipping of an orientation of magnetization of the third layer is induced by thermal fluctuations in the MTJ device.