this paper presents an embedded signal analyzer for AC impedance identification of the PEM fuel cell after a fluctuation signal of current is injected into the stack. The key part of the analyzer is the analog signal processing unit designed with special consideration. The analog signal processing unit has the capability of extracting small fluctuation signals of the current, voltages of the stack and each cell. Phase delays caused by the analog circuit are designed to be the same to avoid complicated phase calibration of original signals. Then the experiment is performed to validate functions of the proposed signal analyzer.