<p>The standard of healthcare services is now being improved via biomedical applications, which are the focus of most technology progress. Since most biomedical equipment is rechargeable and portable, energy-efficient execution is required for all designs. Since analogue signals are the foundation of all communication, digital advancements can only occur when analog signals can be converted into digital ones. In most biomedical devices, the analog-to-digital converter (ADC) is an essential component. Therefore, this review presents an analog front-end design (AFE) for biomedical sensor applications, and the design includes several modules, namely, amplifiers, filters, and ADC modules. This review highlights delta-sigma modulator (DSM) based ADC designs and Successive approximation registers (SAR) based ADC designs for biomedical sensor applications. Additionally, schematic views are provided for the three main ADC design building blocks: the comparator, the digital-to-analog converter (DAC), and the sample and hold (S/H) circuit. In addition to this, the review undergoes several AFE designs, namely, Low-Noise Amplifier (LNA), Programmable Gain Amplifier (PGA), and Variable Gain Amplifier (VGA), for biomedical applications with diagrammatic representations. Moreover, different types of electrodes used in the signal acquisition are discussed by means of different parameters. Numerous ADC designs, amplifiers and filters are eventually addressed in tabular form for improved comprehension. In addition to this, the challenges and future directions are discussed.</p>