LTC1066-1_09 Datasheet, PDF (1/20 Pages) Linear Technology – 14-Bit DC Accurate Clock-Tunable, 8th Order Elliptic or Linear Phase Lowpass Filter

LTC1066-1
14-Bit DC Accurate
Clock-Tunable, 8th Order Elliptic
or Linear Phase Lowpass Filter
FEATURES
■ _{DC Gain Linearity: 14 Bits}
■ _{Maximum DC Offset: ±1.5mV}
■ _{DC Offset TempCo: 7µV/°C}
■ _{Device Fully Tested at fCUTOFF = 80kHz}
■ _{Maximum Cutoff Frequency: 120kHz (VS = ±8V)}
■ _{Drives 1kΩ Load with 0.02% THD or Better}
■ _{Signal-to-Noise Ratio: 90dB}
■ _{Input Impedance: 500MΩ}
■ _{Selectable Elliptic or Linear Phase Response}
■ _{Operates from Single 5V up to ±8V Power Supplies}
■ _{Available in an 18-Pin SO Wide Package}
U
APPLICATIO S
■ _{Instrumentation}
■ _{Data Acquisition Systems}
■ _{Anti-Aliasing Filters}
■ _{Smoothing Filters}
■ _{Audio Signal Processing}
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
DESCRIPTIO
The LTC^®1066-1 is an 8th order elliptic lowpass filter
which simultaneously provides clock-tunability and DC
accuracy. The unique and proprietary architecture of the
filter allows 14 bits of DC gain linearity and a maximum of
1.5mV DC offset. An external RC is required for DC
accurate operation. With ±7.5V supplies, a 20k resistor
and a 1µF capacitor, the cutoff frequency can be tuned
from 800Hz to 100kHz. A clock-tunable 10Hz to 100kHz
operation can also be achieved (see Typical Application
section).
The filter does not require any external active components
such as input/output buffers. The input/output impedance
is 500MΩ/0.1Ω and the output of the filter can source or
sink 40mA. When pin 8 is connected to V ⁺, the clock-to-
cutoff frequency ratio is 50:1 and the input signal is
sampled twice per clock cycle to lower the risk of aliasing.
For frequencies up to 0.75f_CUTOFF, the passband ripple is
±0.15dB. The gain at f_CUTOFF is –1dB and the filter’s
stopband attenuation is 80dB at 2.3f_CUTOFF. Linear phase
operation is also available with a clock-to-cutoff frequency
ratio of 100:1 when pin 8 is connected to ground.
The LTC1066-1 is available in an 18-pin SO Wide package.
TYPICAL APPLICATIO
Clock-Tunable, DC Accurate, 800Hz to 80kHz Elliptic Lowpass Filter
20k
SHORT CONNECTION UNDER
IC AND SHIELDED BY A
GROUND PLANE
BYPASS THE POWER SUPPLIES
WITH 0.1µF DISC CERAMIC
40kHz ≤ f_CLK ≤ 4MHz
1µF
V_IN
–7.5V
7.5V
1 _{OUT A}
V^{+ 18}
2 _{–IN A}
OUT B ¹⁷
3 _{+IN A}
+IN B ¹⁶
4 _V–
LTC1066-1 ^{GND 15}
5 _V+
FILTER_IN ¹⁴
6 _{CONNECT 1}
COMP 2 ¹³
7 _FILTEROUT
8 _50/100
CONNECT 2 ¹²
COMP 1 ¹¹
9 _CLK
V^{– 10}
7.5V
V_OUT;
V_OS(OUT) =
2.5mV_MAX
30k
15pF
–7.5V
1066-1 TA01
10
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
100
Amplitude Response
f_C = 80kHz
f_C = 800Hz
1k
10k
100k
1M
FREQUENCY (Hz)
1066-1 TA02
10661fa
1