Mechanical frequency up-conversion has been suggested by many researchers in order to increase power density of kinetic energy harvesters. In this paper analytical analysis of frequency up-conversion mechanism has been carried out in some detail. It has been shown that sources of actuation for a frequency increased generator can be categorized as force limited and displacement limited sources. Maximum energy transferring conditions have been investigated for both types. The settling time of the transient motion of the high frequency oscillator has been shown to be dependent on the seismic mass. Effects of premature excitation and natural frequency of high frequency resonator on average power have also been investigated. A relationship has been developed between frequency of ambient vibration and optimal natural frequency of frequency increased generator. © 2011 IEEE.