Very Low Noise, Differential Amplifi er and 2.5MHz Lowpass Filter

The LT6600-2.5 combines a fully differential amplifier with a 4th order 2.5MHz lowpass filter approximating a Chebyshev frequency response. Most differential amplifiers require many precision external components to tail or gain and bandwidth. In contrast, with the LT6600-2.5, two external resistors program differential gain, and the filter’s 2.5MHz cutoff frequency and passband ripple are internally set. The LT6600-2.5 also provides the necessary level shifting to set its output common mode voltage to accommodate the reference voltage requirements of A/Ds.

Using a proprietary internal architecture, the LT6600-2.5 integrates an antialiasing filter and a differential amplifier/driver without compromising distortion or low noise performance. At unity gain the measured in band signal-to- noise ratio is an impressive 86dB. At higher gains the input referred noise decreases so the part can process smaller input differential signals without significantly degrading the output signal-to-noise ratio.

The LT6600-2.5 also features low voltage operation. The differential design provides outstanding performance for a 4VP-P signal level while the part operates with a single 3V supply. The LT6600-2.5 is available in SO-8 and DFN-12 packages.

For similar devices with higher cutoff frequency, refer to the LT6600-5, LT6600-10, LT6600-15 and LT6600-20 data sheets.

Applications

* High Speed ADC Antialiasing and DAC Smoothing in Networking or Cellular Basestation Applications

* High Speed Test and Measurement Equipment

* Medical Imaging

* Drop-in Replacement for Differential Amplifiers

* ±0.6dB (Max) Ripple 4th Order Lowpass Filter with

2.5MHz Cutoff

* Programmable Differential Gain via Two External Resistors

* Adjustable Output Common Mode Voltage

* Operates and Specified with 3V, 5V, ±5V Supplies

* 86dB S/N with 3V Supply and 1VRMS Output

* Low Distortion, 1VRMS, 800Ω

Load 1MHz: 95dBc 2nd, 88dBc 3rd

* Fully Differential Inputs and Outputs

* Compatible with Popular Differential Amplifier Pinouts

* SO-8 and DFN-12 Packages