Ultrasound harmonic imaging (UHI) employs nonlinear components in received echoes to improve image quality. Those harmonic signals are often weaker than the signal at the original transmission frequency. To maximize the received harmonic signals, a bandpass filter in the analog front-end (AFE BPF) can be used at an early stage to suppress the signals of less interest, enabling further amplification, which thus provides a better signal-to-noise ratio for the target harmonic. In this work, we present an in-vitro phantom study about the impact of an AFE BPF based on a prototype system for UHI, and we compare this against a digital filter or a pulse-inversion scheme. A 16-channel front-end with a programmable BPF and digitization is proposed to process ultrasound signals received from a capacitive micromachined ultrasonic transducer. Acoustic measurements based on a tissue-mimicking phantom show the feasibility of the AFE BPF approach. Compared to the other methods, the AFE BPF results in higher image contrast or relaxed requirements for the digitizer electronics.