LTC1264-7M Ver la hoja de datos (PDF) - Linear Technology

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LTC1264-7M

Linear Phase, Group Delay Equalized, 8th Order Lowpass Filter

Linear Technology 

LTC1264-7

ELECTRICAL CHARACTERISTICS

Note 1: Absolute Maximum Ratings are those values beyond which the life

of a device may be impaired.

Note 2: Input frequencies, f, are linearly phase shifted through the filter as

long as f ≤ fC; fC = cutoff frequency.

Figure 1 curve (A) shows the typical phase response of an LTC1264-7

operating at fCLK = 2.5MHz, fC = 100kHz. An endpoint straight line, curve

(B), depicts the ideal linear phase response of the filter. It is described by:

phase shift = 180° – F (f/fC); f ≤ fC.

F is arbitrarily called the “phase factor” expressed in degrees. The phase

factor together with the specified deviation from the ideal straight line

allows the calculation of the phase at a given frequency. Note, the

maximum phase nonlinearity, Figure 1, occurs at the vicinity of f = 0.25 fC

and = 0.75 fC. Example: The phase shift at 70kHz of the LTC1264-7 shown

in Figure 1 is: phase shift = 180° – 407° (70kHz/100kHz) ± nonlinearity =

–104.9° ± 1% or –104.9° ± 1.05°.

Note 3: Group delay and group delay deviation are calculated from the

measured phase factor and phase deviation specifications.

Note 4: The filter cutoff frequency is abbreviated as fCUTOFF or fC.

Note 5: The AC swing is typically 9VP-P, 5.6VP-P, 1.8VP-P with ± 7.5V, ± 5V,

± 2.5V supply respectively. For more information refer to the THD + Noise

vs Input graphs.

180

fCLK = 2.5MHz

90

(fCLK/fC) = 25:1

0

– 90

–180

B

A

–270

–360

0

10 20

30 40 50 60 70 80 90 100

FREQUENCY (kHz)

LTC1264-7 F01

Figure 1. Phase Response in the Passband (Note 2)

12647fa

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