LTC1564 Datasheet, PDF (1/12 Pages) Linear Technology – 10kHz to 150kHz Digitally Controlled Antialiasing Filter and 4-Bit P.G.A

LTC1564
10kHz to 150kHz
Digitally Controlled
Antialiasing Filter and 4-Bit P.G.A
FEATURES
s _{4-Bit Digitally Controlled 8th-Order Lowpass Filter}
– f_CUTOFF Adjustable from 10kHz to 150kHz in 10kHz
Steps
– 100dB Attenuation at 2.5 × f_CUTOFF
s _{4-Bit Digitally Controlled Programmable Gain}
Amplifier
– G = 1 to 16 in 1V/V Steps
s _{Miniature 16-Pin SSOP Package}
s _{No External Components}
s _{122dB Total System Dynamic Range}
s _{Rail-to-Rail Input and Output Range}
s _{2.7V to 10V Operation}
s _{Low Noise Mute Mode}
s _{Low Power Shutdown Mode}
U
APPLICATIO S
s _{Antialias or Reconstruction Filtering}
s _{DSP Systems}
s _{Communications Systems}
s _{Scientific Instruments}
s _{High Resolutions (16 Bits to 20 Bits)}
s _{Processing Signals Buried in Noise}
s _{Audio Signal Processing}
s _{Programmable Data Rates}
s _{Automatic Gain Control (AGC)}
s _{Single Part Replacing Multiple Filters}
DESCRIPTIO
The LTC^®1564 is a new type of continuous time filter for
antialiasing, reconstruction and other band-limiting appli-
cations. No other analog components or filter expertise are
needed to use it. There is one analog input pin and one
analog output pin. The cutoff frequency (f_C) and gain are
programmable while the shape of the lowpass response is
fixed. A latching digital interface stores f_C and gain settings
or it can be bypassed for control directly from the pins. The
LTC1564 operates from 2.7V to 10V total (single or split
supplies) and comes in a 16-pin surface mount SSOP.
The LTC1564 is a rail-to-rail high resolution 8th-order
lowpass filter with two stopband notches, giving approxi-
mately 100dB attenuation at 2.5 times the passband cutoff
frequency f_C (a de-facto standard for DSP front ends).
Signals with low or variable levels can be normalized with
the built-in variable gain that reduces input-referred noise
with increasing gain for a typical dynamic range (maxi-
mum signal level to minimum noise) of 122dB (20 equiva-
lent bits) with 20kHz f_C and 118dB at 100kHz f_C on a ±5V
supply.
Other frequency-response shapes can be provided upon
request. Please contact LTC Marketing.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
Low Noise Programmable Filter with Variable Gain
ANALOG
IN
V⁺
0.1µF
GAIN CODE
16 15 14 13 12 11 10 9
IN AGND V⁺ RST G3 G2 G1 G0
LTC1564
CS/
OUT V^– EN HOLD F3 F2 F1 F0
1 2 34 5 6 7 8
V⁺ AND V^– SUPPLIES CAN BE FROM
1.35V TO 5.25V EACH
TIE F AND G PINS TO V⁺ OR V^– TO
SET FREQUENCY AND GAIN
DYNAMIC RANGE 118dB TO 122dB
AT ± 5V DEPENDING ON FREQUENCY CODE
ANALOG
OUT
0.1µF
FREQUENCY CODE
V^–
1564 TA01
LTC1564 Programmable Range
30
20
10
0
–10
–20
–30
–40
–50
–60
–70 fC = 10kHz
–80 ^{GAIN = 1V/V}
–90
–100
–110
–120
5 10
f_C = 150kHz
GAIN = 16V/V
100
FREQUENCY (kHz)
500
1564 TA02
1