8th-Order, Lowpass, Elliptic,

Switched-Capacitor Filters

_______________________________________________________________________________________

5

Note 1: The maximum fC is defined as the clock frequency, fCLK = 100 · fC, at which the peak SINAD drops to 68dB with a

sinusoidal input at 0.2fC.

Note 2: DC insertion gain is defined as

∆VOUT / ∆VIN.

Note 3: OS voltages above VDD - 1V saturate the input and result in a 75µA typical input leakage current.

Note 4: For MAX7400/MAX7403, fOSC (kHz) ≅ 38 · 103 / COSC (pF). For MAX7404/MAX7407, fOSC (kHz) ≅ 34 · 103 / COSC (pF).

Note 5: The input frequencies, fIN, are selected at the peaks and troughs of the frequency responses.

ELLIPTIC (r = 1.2) FILTER CHARACTERISTICS—MAX7403/MAX7407

(VDD = +5V for MAX7403, VDD = +3V for MAX7407; filter output measured at OUT; 10kΩ || 50pF load to GND at OUT; SHDN = VDD;

VCOM = VOS = VDD / 2; fCLK = 100kHz; TA = TMIN to TMAX; unless otherwise noted. Typical values are at TA = +25°C.)

Typical Operating Characteristics

(VDD = +5V for MAX7400/MAX7403, VDD = +3V for MAX7404/MAX7407; VCOM = VOS = VDD / 2; SHDN = VDD; fCLK = 100kHz;

TA = +25°C; unless otherwise noted.)

-120

-80

-100

-40

-60

0

-20

20

012345

MAX7400/MAX7404 (r = 1.5)

FREQUENCY RESPONSE

INPUT FREQUENCY (kHz)

fC = 1kHz

-0.08

0

-0.04

0.12

0.08

0.04

0.20

0.16

0.24

0

202

404

606

808

1010

MAX7400/MAX7404 (r = 1.5)

PASSBAND FREQUENCY RESPONSE

INPUT FREQUENCY (Hz)

fC = 1kHz

-640

-480

-560

-240

-320

-400

-80

-160

0

0

300

600

900

1200

1500

MAX7400/MAX7404 (r = 1.5)

PHASE RESPONSE

INPUT FREQUENCY (Hz)

fC = 1kHz

PARAMETER

MIN

TYP

MAX

UNITS

-58

-50

-60

-54

Insertion Gain Relative to DC Gain

(Note 5)

-60

-54

fIN = 1.533fC

dB

fIN = 2.875fC

-59

-54

fIN = 1.200fC

fIN = 1.261fC

-0.20

0.10

0.20

-0.20

0.14

0.30

CONDITIONS

-0.20

0.09

0.30

fIN = 0.992fC

fIN = 1.000fC

-0.20

0.02

0.20

fIN = 0.902fC

fIN = 0.956fC

-0.20

0.02

0.20

-0.20

-0.06

0.20

fIN = 0.640fC

fIN = 0.784fC

-0.20

-0.11

0.20

fIN = 0.408fC