Safety-critical systems such as automated embedded or industrial systems have a strong dependency on the trustworthiness of data collection. As sensors are the critical component for those systems, it is imperative to address the attack resilience of sensors. System-level defense methods typically do not differentiate the root cause and recover the system from attack with the same procedure, thus resulting in unnecessary costs. In this work, we propose a circuit-level solution to handle security challenges in a temperature sensor. The complementary current-temperature characteristics are exploited to generate a constant current reference for attack detection. Experimental results show that our sensor is capable of detecting an under-powering attack from a significant residual vibration in the constant current reference. Furthermore, our sensor can spot an active analog Trojan by analyzing substantial current deviation in a wide range of temperatures. These high sensitivities against the under-powering and analog Trojan attacks make the sensor resilient against attacks at the circuit level. The proposed sensor consumes 17% less power and 11% higher power-supply-rejection-ratio.