Not Recommended for New Designs

LMF100

SNOSBG9B – JULY 1999 – REVISED JUNE 2015

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8 Detailed Description

8.1 Overview

The LMF100 device contains two general-purpose, very high-performance switched capacitor filters that are cost-

effective and space-saving. It enables designers to implement all the classical filters up to fourth-order biquad

with one chip. This switched capacitor filters can be used in a broad range of industrial and consumer application

such as audio, communication, instrumentation, medical, telemetry, etc. It can be directly cascaded to implement

higher order filters,

8.2 Functional Block Diagram

8.3 Feature Description

The LMF100 is an all CMOS switched capacitor filter device that consists of two filters capable of wide supply

range from 4 V to 15 V. It features much higher performance than the pin-compatible MF10 device with operation

frequency to 100 kHz, which is 3X broader, and fo x Q range to 1.8 MHz which is 9X higher. Furthermore, it has

pins that also function to configure filter modes of operation, level shifting, clock to filter center frequency setting,

and power rail selections enabling flexibility and ease of programming.

8.4 Device Functional Modes

8.4.1 Modes of Operation

The LMF100 is a switched capacitor (sampled data) filter. To fully describe its transfer functions, a time domain

analysis is appropriate. Because this is cumbersome, and because the LMF100 closely approximates continuous

filters, the following discussion is based on the well-known frequency domain. Each LMF100 can produce two full

second-order functions. See Table 1 for a summary of the characteristics of the various modes.

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