In the proposed model, the equivalent circuit of resonant tunneling structure including anonlinear negative differential resistance element, a series resistance, a junction capacitance, andtwo inductances is explored. The characteristic of negative differential resistance is constructed byusing the relationship of current to voltage curve. As the bias voltage of resonant tunneling structureis increased, the output current density of resonant tunneling structure is decreased. We canunderstand the spontaneous oscillation frequency (fSR) is inversely proportional internal inductance(LQ1). The fSR will be increased, as the internal inductance is decreased. The resistive cutofffrequency (fr) of oscillation will be not the influence of internal inductance (LQ1). When the externalinductance (LQ2) is increased, the self-resonant frequency of oscillation will decrease nonlinearly.The external inductance (LQ2) will increase nonlinearly, as the external inductance (LQ2) is increased.The sum of load resistance (RL) and series resistance (RS) must be less than negative differentialresistance (RN) which the stable phenomena will occur. The current (IS) of resonant differentialstructure will also be the influence of the inductances including load inductance (LL) and externalinductance (LQ2).