This paper presents a new analog front-end architecture for heartbeat detection at the circuit level, presenting ultra-low power, thus suitable for wearable biomedical and healthcare applications. The front-end circuit is developed in 65-nm CMOS to detect heartbeats with high accuracy directly from the analog signal, avoiding converting to the digital domain and consuming significantly less power than
the current state-of-the-art. After an initial amplification, the detection system detects the maximum and minimum of each beating to set an appropriate threshold, while in parallel delays, the input signal is to be compared after the threshold is set, ensuring a high accuracy and noise tolerance. From simulation results on actual wrist electrocardiogram data with different characteristics and conditions, the system shows a high detection accuracy of 96 % while consuming only 25 nW from a 0.6 V source.