By analyzing working principle of force-balanced accelerometer

and using analytical method

the relation of input inertial force and mass block’s displacement is derived.Both the states of"stiffening"and"softening"are involved in the procedure of operation

which is different from the open-loop accelerometer which only involve the state of"softening".The stiffness coupling value is defined as the ratio of electrostatic stiffness and mechanical stiffness of block’s displacement.Analysis indicates that the dividing point of"stiffening"and"softening"is where the coupling value equals to zero

and dividing point of"positive"and"negative"stiffness is where the coupling value equals to-1

the sharpness of coupling curve reflects the permitted displacement and coupling nonlinearity

the lager is the amplitude of stiffness coupling value

the more sharp is the curve

and the larger is the nonlinearity

the smaller is the displacement permitted by massblock.