The LTC1560-1 is a 5th order, continuous-time, lowpass filter. The elliptic transfer function of the LTC1560-1 was carefully chosen to reach a compromise between selectivity, for antialiasing applications, and transient response. The filter cutoff frequency, fCUTOFF, 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 0.55fCUTOFF and ±0.3dB to 0.9fCUTOFF. The transition band gain is –24dB at 1.4fCUTOFF and –51dB at 2fCUTOFF. Stopband attenuation is 63dB at 2.43fCUTOFF and above, remaining at least 60dB to 10MHz with proper board layout. When the LTC1560-1 is programmed for fCUTOFF = 500kHz, the filter response closely follows the 1MHz case with the exception of passband flatness near the cutoff frequency; the gain at fCUTOFF is –1.3dB.
The LTC1560-1, unlike other high frequency filters, is designed for low noise and low distortion. With a 1VRMS input signal, the signal-to-noise ratio is 69dB and the THD is –63dB. The maximum SNR of 75dB is obtained with a 2.1VRMS 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.
Applications
- Antialiasing Filters
- Smoothing or Reconstruction Filters
- Communication Filters
