ADA4417-3

Rev. 0 | Page 12 of 16

THEORY OF OPERATION

The ADA4417-3 is a low cost, integrated video filtering and

driving solution that offers a 38 MHz, 1 dB bandwidth to meet

the requirements of high definition video. Each of the three

filters has a sixth-order Butterworth response that includes

group delay equalization. Group delay variation from 1 MHz to

36 MHz is only 5 ns, resulting in greater stop-band attenuation

and minimal phase distortion.

The ADA4417-3 is designed to operate in many video

environments. With a supply range of 3.3 V to 5 V, it requires

a relatively low nominal quiescent current of 10 mA per

channel. This makes the ADA4417-3 well suited for portable

high definition video applications. Additionally, for other low

power applications, the part can be powered down to draw

typically 10 μA by pulling the DISABLE pin to ground. The

ADA4417-3 is also well suited for high encoding frequency

applications because it maintains a stop-band attenuation of over

40 dB out to 500 MHz. Typical power supply rejection ratio

(PSRR) is greater than 70 dB, providing excellent rejection in

systems with supplies that are noisy or underregulated.

The ADA4417-3 is intended to accept dc-coupled inputs

from an encoder or other ground-referenced video signals.

The ADA4417-3 inputs are high impedance. No minimum or

maximum input termination is required; however, terminations

above 1 kΩ may degrade crosstalk performance at high

frequencies.

Each filter input includes level-shifting circuitry. The level-

shifting circuitry adds a dc component of 100 mV to ground-

referenced input signals so that they reproduce accurately,

without the output buffers hitting the ground rail. For lowest

off state power consumption when using the dc offset function,

it is recommended that the DCO and DISABLE pins be tied

together.

The output drivers on the ADA4417-3 have rail-to-rail output

capabilities with 6 dB gain. Each output is capable of driving

two ac- or dc-coupled, 75 Ω source-terminated loads. If a large

dc output level is required while driving two loads, ac coupling

should be used to limit the power dissipation.