An equivalent circuit of a tunnel diode is 

Key Points

 A basic equivalent circuit of a tunnel diode consists of ;

series inductance Ls, 

the series resistance Rs, 

the diode capacitance Cj 

the negative resistance = R.

Additional Information

•  A tunnel diode (also known as a Esaki diode) is a type of semiconductor diode that has effectively “negative resistance” due to the quantum mechanical effect called tunneling.
• Tunnel diodes have a heavily doped pn junction that is about 10 nm wide.
• The heavy doping results in a broken band gap, where conduction band electron states on the N-side are more or less aligned with valence band hole states on the P-side.