Norton Equivalent Butterworth Filter for Meeting Rigid Disk Drive Data Channel Requirements
Original Publication Date: 1985-Sep-01
Included in the Prior Art Database: 2005-Feb-19
Norton equivalent filter provides low pole sensitivity to variations in resistance/inductance/capacitance (RLC) components of Butterworth filters, without reducing the driver's output signal voltage. Read data channel performance in a magnetic disk drive is more consistent, causing fewer file rejects at final test with more consistent file operation in the field. Rigid disk file products have commonly used either a balanced voltage-driven Butterworth filter or an unbalanced current- driven Butterworth filter. The balanced voltage-driven configuration offers low transfer function sensitivity to component tolerance variations in the RLC values. However, the in-band output signal voltage is reduced by the resistor divider factor which is typically 0.5 for a balanced load.