Active Filters: High Pass

Active 2nd Order Filters:

Basic Introduction to Filters: application notes on active, passive and switched capacitor filters, document in PDF format

Butterworth Filters:

Chebyshe Volt / Butterworth Filters:

Chebyshe Volt Bandpass Filter:

Highpass Filters use Modified Equalelement Design: EDN-Design Ideas / (added 5/03) PDF contains multiple circuits - scroll to find this circuit.