公开(公告)号：US20250112596A1

公开(公告)日：2025-04-03

申请号：US18480322

申请日：2023-10-03

Applicant: STMicroelectronics International N.V.

Inventor： Alessio Emanuele Vergani ,  Francesco Piscitelli ,  Michele Bartolini

IPC: H03F1/02 ,  H03K5/24 ,  H03K19/20

Abstract: According to an embodiment, an envelope detector circuit for detecting an envelope of a signal from a sensor in a pre-amplifier circuit of a hard disk drive is provided. The circuit includes a half-wave rectifier, a low-pass filter, and a differential full-wave rectifier. The half-wave rectifier receives a differential voltage from the sensor indicating a fly height of the hard disk drive and generates a pair of single-ended output waveforms based on the differential voltage. Each pair of single-ended output waveforms has a positive polarity for a half-cycle it passes through. The low-pass filter includes a first and a second low-pass filter. The low-pass filter allows low-frequency signals from the pair of single-ended output waveforms to pass through while attenuating or blocking higher-frequency signals. The differential full-wave rectifier reconstructs a differential signal from the low-pass filter while removing DC rectified components.