Detection of Cardiac Signal Characteristic Point Using Log-Domain Wavelet Transform Circuits

To meet the requirement of low power consumption in biomedical implantable pacemaker applications, a novel method based on balanced log-domain wavelet transform (WT) circuits has been developed for detecting QRS complexes of cardiac signals. By using a hybrid particle swarm optimization algorithm (PSO) combined with sequential quadratic programming, an excellent approximation of the first derivative of a Gaussian wavelet is achieved. The WT circuits are composed of filters whose impulse response is the approximation of the Gaussian wavelet. The WT filter design is based on a time inverse follow-the-leader feedback structure with class-AB balanced log-domain integrators as the main building blocks. HSPICE simulation shows that the power consumption is only 62 nW per scale for a 1.2 V supply, and the dynamic range is 86 dB for 2% total harmonic distortion. The high accuracy of the QRS complex detection method has been validated using the MIT-BIH database.