I'm designing an ATMega128 board w/ the TQFP package. I have no plans to use the ADC but figure I might as well set things up so I can in the future. The only discussion of layout considerations in the datasheet (nothing in the app notes I can find) is the suggestion that AVCC should be connected to VCC via a low-pass filter. I'm pretty lame when it comes to analog stuff so, while I know in general what a low-pass filter is, I have no idea what's called for in this application. What have other people done or seen? Are there other considerations? I'm planning on just a 2-layer board. Thanks.