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LTC1264-7

Linear Phase, Group Delay

Equalized, 8th Order

Lowpass Filter

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FEATURE

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Steeper Roll-Off Than Bessel Filters

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Phase Equalized Filter in a 14-Pin Package

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Phase and Group Delay Response Fully Tested

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Transient Response Exhibits 5% Overshoot and

No Ringing

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65dB THD or Better Throughout a 100kHz Passband

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No External Components Needed

DESCRIPTIO

The LTC1264-7 is a clock-tunable monolithic 8th order

lowpass filter with linear passband phase and flat group

delay. The amplitude response approximates a maximally

flat passband and exhibits steeper roll-off than an equiva-

lent 8th order Bessel filter. For instance, at twice the cutoff

frequency the filter attains 28dB attenuation (vs 12dB for

Bessel), while at three times the cutoff frequency the filter

attains 55dB attenuation (vs 30dB for Bessel). The cutoff

frequency of the LTC1264-7 is tuned via an external TTL or

CMOS clock.

The clock-to-cutoff frequency ratio of the LTC1264-7 can

When the filter operates at clock-to-cutoff frequency ratio

of 25:1, the input is double-sampled to lower the risk of

aliasing.

The LTC1264-7 is optimized for speed. Depending on the

operating conditions, cutoff frequencies between 200kHz

and 250kHz can be obtained. (Please refer to the Passband

vs Clock Frequency graphs.)

The LTC1264-7 is pin-compatible with the LTC1064-X

series.

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APPLICATI

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Data Communication Filters

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Time Delay Networks

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Phase Matched Filters

APPLICATI

TYPICAL

200kHz Linear Phase Lowpass Filter

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14

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LTC1264-7

8V

–8V

8V

NOTE: THE POWER SUPPLIES SHOULD BE BYPASSED BY A

0.1

µF CAPACITOR CLOSE TO THE PACKAGE AND ANY PRINTED

CIRCUIT BOARD ASSEMBLY SHOULD MAINTAIN A DISTANCE

OF AT LEAST 0.2 INCHES BETWEEN ANY OUTPUT OR INPUT

1264-7 TA01

4-Level PAM Eye Diagram

1264-7 TA02

500ns/DIV