LT1568
6
1568f
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Filter Gain Mismatch f
C
= 1MHz, f
IN
= f
C
● –0.3 ±0.10 0.3 dB
(V
OUTA
– V
OUTA
) – (V
OUTB
– V
OUTB
) f
C
= 10MHz, f
IN
= f
C
● –0.4 ±0.15 0.4 dB
Wideband Output Noise f
C
= 1MHz, R
FIL
= 1.28k, BW = 2MHz 36 µV
RMS
f
C
= 10MHz, R
FIL
= 128Ω, BW = 20MHz 88 µV
RMS
THD Total Harmonic Distortion f
C
= 1MHz, R
FIL
= 1.28k, –84 dB
f
IN
= 200kHz, V
IN
= 1V
P-P
f
C
= 10MHz, R
FIL
= 128Ω,–69dB
f
IN
= 2MHz, V
IN
= 1V
P-P
Note 1: Absolute Maximum Ratings are those values beyond which the life
of the device may be impaired.
Note 2: The inputs of each op amp are protected by back-to-back diodes.
If either differential input voltage exceeds 1.4V, the input current should be
limited to less than 10mA.
Note 3: A heat sink may be required to keep the junction temperature
below the absolute maximum rating when the output is shorted
indefinitely.
Note 4: The inverter bandwidth is measured with the SA or SB output
floating, and is defined as the frequency at which the phase shift from
OUTA (OUTB) to OUTA (OUTB) drops from 180° to 135°.
Note 5: Measured with the SA or SB output connected in the filter
application circuit as shown in the Block Diagram.
Note 6: The common mode input voltage range is measured by shorting
the filter input to the common mode reference (GNDA or GNDB) and
applying a DC input voltage to search for the common mode voltage range
that creates a ±2mV (V
S
= 3V) or ±5mV (V
S
= ±5V) change in the (OUTA
or OUTB) voltage (measured with respect to GNDA or GNDB).
Note 7: The minimum cutoff frequency of the LT1568 is arbitrarily listed
as 200kHz. The limit is arrived at by setting the maximum resistor value
limit at 6.4k. Due to input bias current, the output DC offset through a
single section can be as high as 25mV with resistors this large. The
LT1568 can be used with even larger resistors if the large offset voltages
can be tolerated. For cutoff frequencies below 200kHz, refer to the
LTC1563-2, LTC1563-3.
Note 8: With equal-sized resistors, the differential DC gain through either a
single section or cascaded sections is 6dB.
Note 9: The LT1568C is guaranteed to meet specified performance from
0°C to 70°C. The LT1568C is designed, characterized and expected to
meet specified performance from –40°C to 85°C but is not tested or QA
sampled at these temperatures. The LT1568I is guaranteed to meet
specified performance from –40°C to 85°C.
Specifications are for the
differential output (OUTA – OUTA or OUTB
– OUTB) of a single 2nd order section
(A or B), gain = –2,
R
FIL
= R11 = R21 = R31 = R12 = R22 = R32. All voltages are with respect to V
GND
= V
GNDA
= V
GNDB
. The ● denotes the specifications
which apply over the full operating temperature range, otherwise specifications and typical values are at T
A
= 25°C.
V
S
= single 5V, EN pin to logic “low,” R
LDIFF
= 800Ω connected to midsupply, unless otherwise noted.
FILTER ELECTRICAL CHARACTERISTICS
