LMF60 High Performance 6th-Order Switched Capacitor Butterworth Lowpass Filter

The LMF60 is a high performance, precision, 6th-order Butterworth lowpass active filter. It is fabricated using National’s LMCMOS process, an improved silicon-gate CMOS process specifically designed for analog products. Switchedcapacitor techniques eliminate external component requirements and allow a clock-tunable cutoff frequency. The ratio of the clock frequency to the low-pass cutoff frequency is internally set to 50:1 (LMF60-50) or 100:1 (LMF60-100). A Schmitt trigger clock input stage allows two clocking options, either self-clocking (via an external resistor and capacitor) for stand-alone applications, or for tighter cutoff frequency control, a TTL or CMOS logic compatible clock can be directly applied. The maximally flat passband frequency response together with a DC gain of 1V/V allows cascading LMF60 sections for higher-order filtering. In addition to the filter, two independent CMOS op amps are included on the die and are useful for any general signal conditioning applications. The LMF60 is pinand functionally-compatible with the MF6, but provides improved performance. Features Y Cutoff frequency range of 0.1 Hz to 30 kHz Y Cutoff frequency accuracy of g1.0%, maximum Y Low offset voltage g100 mV, maximum, g5V supply Y Low clock feedthrough of 10 mVp–p, typical Y Dynamic range of 88 dB, typical Y Two uncommitted op amps available Y No external components required Y 14-pin DIP or 14-pin wide-body S.O. package Y Single/Dual Supply Operation: a4V to a14V (g2V to g7V) Y Cutoff frequency set by external or internal clock Y Pin-compatible with the MF6