This paper presents the design, manufacture, and testing of a trans-impedance amplifier for a miniaturized saturated absorption spectrometer. The amplifier has a bandwidth of 32 kHz, a dc gain of 80.3 dB-Ohm, and an output voltage swing of 4.84 V_pp. The device can handle an input optical power up to 800 μW, where the photodetection electronics have a Noise Equivalent Power of 0.3 pW/√Hz. The circuit board has a size of 27 × 27 mm². Signals acquired with our miniaturized device perfectly match those recorded with a commercial tabletop optical setup.