This brief presents a low-power oscillatory synchronization feature extraction (FE) unit for phase-amplitude coupling (PAC) and phase locking value (PLV) features. The proposed FE unit uses a new multiplier-less wavelet approximation in combination with a multi-rate lowpass filter bank for low-power complex signal extraction. Further power and area reductions are obtained by utilizing a light sine and cosine extractor (LSCE) for the feature computation. The synthesized 32-channel design achieves state-of-the-art performances in post-layout simulations at 430 nW/channel and 0.36 mm2 while maintaining sufficient accuracy for seizure detection in epileptic patients.