SSI32F8030

SSI 32F8030 ® A TDK Group Company Programmable Electronic Filter April 1995 DESCRIPTION The SSI 32F8030 Programmable Electronic Filter provides an electronically controlled low–pass filter with a separate differentiated low–pass output. A seven– pole, 0.05° Equiripple-type linear phase, low–pass filter is provided along with a single-pole, single-zero differentiator. Both outputs have matched delays. The delay matching is unaffected by any amount of programmed high frequency peaking (boost) or bandwidth. This programability, combined with low group delay variation makes the SSI 32F8030 ideal for use in many applications. Double differentiation high frequency boost is accomplished by a two–pole, low– pass with a two–pole, high–pass feed forward section to provide complementary real axis zeros. A variable attenuator is used to program the zero locations, which controls the amount of boost. The SSI 32F8030 programmable boost and bandwidth characteristics can be controlled by external DACs or DACs provided in the SSI 32D4661 Time Base Generator. Fixed characteristics are easily accomplished with three external resistors. In addition, boost can be switched in or out by a logic signal. The SSI 32F8030 requires only a +5V supply and is available in 16-Lead SON, and SOL packages. FEATURES • • • • • • • • • • Ideal for: - constant density recording applications - magnetic tape recording Programmable filter cutoff frequency (ƒc = 250 kHz to 2.5 MHz) Programmable high frequency peaking (0 to 9 dB boost at the filter cutoff frequency) Matched normal and differentiated low-pass outputs Differential filter input and outputs ±3.0% group delay variation from 0.2 ƒc to 1.75 ƒc, 0.25 MHz ≤ ƒc ≤ 2.5 MHz Total harmonic distortion less than 1% +5V only operation 16-Lead SON, and SOL packages 5 mW idle mode BLOCK DIAGRAM PIN DIAGRAM VIN+ VIN- Low Pass Filter Summer Low Pass Filter VO_NORM+ VO_NORM- GND1 VO_NORMVO_NORM+ 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 VO_DIFF+ VO_DIFFPWRON VR VCC2 IFP VFP GND2 High Pass Filter Variable Atten. High Pass Filter VO_DIFF+ VO_DIFF- VCC1 VINVIN+ VBP IFP VFP FBST GND1 GND2 VCC1 VCC2 VREF Filter Control BIAS PWRON VR VBP FBST CAUTION: Use handling procedures necessary for a static sensitive component. 04/14/95 - rev. 1 SSI 32F8030 Programmable Electronic Filter FUNCTIONAL DESCRIPTION The SSI 32F8030, a high performance programmable electronic filter, provides a low pass 0.05° Equirippletype linear phase seven pole filter with matched normal and differentiated outputs. The device has been optimized for usage with several Silicon Systems products, including the SSI 32D4661 Time Base Generator, the SSI 32P54x family of Pulse Detectors, and the SSI 32P4720 Combo device (Data Separator and Pulse Detector). CUTOFF FREQUENCY PROGRAMMING The SSI 32F8030 programmable electronic filter can be set to a filter cutoff frequency from 250 kHz to 2.5 MHz (with no boost). Cutoff frequency programming can be established using either a current source fed into the IFP pin, whose output current is proportional to the SSI 32F8030 output reference voltage VR, or by means of an external resistor tied from the output voltage reference pin VR to pin VFP. The former method is optimized using the SSI 32D4661 Time Base Generator, since the current source into pin IFP is available at the DAC F output of the 32D4661. Furthermore, the voltage reference input is supplied to pin VR3 of the 32D4661 by the reference voltage VR from the VR pin of the 32F8030. This reference voltage is an internally generated bandgap reference, which typically varies less than 1 % over voltage supply and temperature variation. (For the calculations below IVFP = current into IFP or VFP pins). The cutoff frequency, determined by the -3dB point relative to a very low frequency value (< 10kHz), is related to the current IVFP injected into pin IFP by the formula Fc (ideal, in MHz) = 3.125•IFP = 3.125•IVFP•2.2/VR, where IFP and IVFP are in mA, 0.08