LTC1560-1 Datasheet, PDF (1/8 Pages) Linear Technology – 1MHz/500kHz Continuous Time, Low Noise, Lowpass Elliptic Filter

LTC1560-1
1MHz/500kHz
Continuous Time,
Low Noise, Lowpass Elliptic Filter
FEATURES
s _{5th Order, 1MHz Elliptic Filter in SO-8 Package}
s _{Pin Selectable 1MHz/500kHz Cutoff Frequency}
s _{Signal-to-Noise Ratio (SNR): 75dB}
s _{Signal-to-Noise Ratio with – 63dB THD: 69dB}
s _{Passband Ripple (fCUTOFF = 1MHz): ±0.3dB}
s _{Stopband Attenuation Better Than 60dB}
s _{No External Components Required}
U
APPLICATIONS
s _{Antialiasing Filters}
s _{Smoothing or Reconstruction Filters}
s _{Communication Filters}
DESCRIPTION
The LTC^®1560-1 is a 5th order, continuous-time, lowpass
filter. The elliptic transfer function of the LTC1560-1 was
carefully chosen to reach a compromise between selectiv-
ity, for antialiasing applications, and transient response.
The filter cutoff frequency, f_CUTOFF, is pin selectable to
either 500kHz (Pin 5 to V ⁺) or 1MHz (Pin 5 to V ^–). When
programmed for 1MHz, the passband ripple is typically
±0.2dB up to 0.55f_CUTOFF and ±0.3dB to 0.9f_CUTOFF. The
transition band gain is – 24dB at 1.4f_CUTOFF and – 51dB at
2f_CUTOFF. Stopband attenuation is 63dB at 2.43f_CUTOFF and
above, remaining at least 60dB to 10MHz with proper
board layout. When the LTC1560-1 is programmed for
f_CUTOFF = 500kHz, the filter response closely follows the
1MHz case with the exception of passband flatness near
the cutoff frequency; the gain at f_CUTOFF is – 1.3dB.
The LTC1560-1, unlike other high frequency filters, is
designed for low noise and low distortion. With a 1V_RMS
input signal, the signal-to-noise ratio is 69dB and the THD
is – 63dB. The maximum SNR of 75dB is obtained with a
2.1V_RMS input signal. This results in – 46dB THD.
The LTC1560-1 operates with ±5V supplies, has a power
saving mode and is available in an SO-8 surface mount
package.
Other cutoff frequencies from 450kHz to 1.5MHz can be
obtained. Demo board DC135A is available for the
LTC1560-1. For more information please contact LTC
Marketing.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATION
– 5V
0.1µF
1MHz/500kHz Elliptic Lowpass Filter
V_IN
0.01µF
1
GND
8
V_OUT
2
V_IN
7
SHDN
3
LTC1560-1
GND
V⁺
6
4 _V–
5
0.5f_C / f_C
V_OUT
(OR – 5V)
0.1µF
5V
0.01µF
– 5V
1MHz
5V
500kHz
1560-1 TA01
Frequency Response
10
0
–10
– 20
– 30
– 40
– 50
– 60
– 70
– 80
f_CUTOFF = 1MHz/500kHz
– 90
0.1
1
FREQUENCY (MHz)
10
1560-1 TA02
1