In this work, a high frequency pulse width modulation (PWM) integrated circuit (IC) designed and implemented in a commercial 0.35 mu m CMOS process is presented. Based on natural sampling method, the proposed PWM IC can generate both a PWM signal and its inverse for arbitrary frequencies up to 5 MHz. The PWM frequency can he adjusted via an external clock and an off-chip capacitor. The duty cycle of the PWM signal can be linearly varied from 5% to 95% by changing the input signal. Thanks to its analog triangle wave generation, it provides higher resolution and less quantization error compared to digital implementations. Moreover, the natural sampling based PWM generation offers reduced harmonic distortion over other PWM generation methods. The PWM IC requires a single 5 V supply voltage to operate. The full chip area is 1.4x1.8 mm(2), including the pad frame. The post-layout simulations reveal that the proposed PWM IC will be a compact and high performance solution for power converters and class D power amplifiers.