Some embodiments of the present disclosure relate to a stacked integrated chip structure having a thermal sensor that detects a temperature of one or a plurality of integrated chips. In some embodiments, the stacked integrated chip structure has a main integrated chip and a secondary integrated chip located on an interposer wafer. The main integrated chip has a reference voltage source that generates a bias current. The secondary integrated chip has a second thermal diode that receives the bias current and based thereupon generates a second thermal sensed voltage and a second reference voltage that is proportional to a temperature of the secondary integrated chip. A digital thermal sensor within the main integrated chip determines a temperature of the secondary integrated chip based upon as comparison of the second thermal sensed voltage and the reference voltage.