This paper presents the design of a 4th-order mult-istage feedforward operational amplifier (op amp) for applications in continuous-time bandpass delta-sigma modulators. On the system-level, a design procedure is proposed to determine the transconductance of each stage. On the transistor-level, curren-treusing is emphasized to achieve power efficiency. Simulated in a 65 nm CMOS process, the op amp achieves over 40 dB gain up to 500 MHz and over 10 dB gain up to 2 GHz with 10 mW power consumption.