Since you posted this in the uc section, you want to create the PWM signals by using a microcontroller? Do you own a microcontroller already, or do you need help choosing one for easily creating PWM signals?
You can also create PWM signals by using ne NE555 timer IC, a quick google (555 timer circuit) should help you along the way.
Hi,
You should mention which microcontroller you are going to use: AVR, PIC, MSP, ST7, etc
You should also mention the language and compiler you are going to program in: mikroC, mikroBASIC, mikroPASCAL, CCS, Hi-Tech, WinAVR, IAR, etc.
From your description this might be closer to what you're after, though the output will need some drivers. The frequency and duty cycle are totally independent, and each control is stable.