EL4390CN INTERSIL [Intersil Corporation], EL4390CN Datasheet - Page 11

• Manufacturer Part Number: EL4390CN
• Description: Triple 80MHz Video Amplifier with DC Restore
• Manufacturer: INTERSIL [Intersil Corporation]

In Figure 3, one of the three channels is used, together with
a low-offset op-amp, to automatically trim the bias current of
the other two channels. The two remaining channels are
shown in the non-inverting configuration, but could equally
well be set to provide inverting gains. Two DC-restored
channels are typically needed in fader applications. See the
EL4094 and EL4095 for suitable, monolithic video faders.
Layout and Dissipation Considerations
As with all high frequency circuits, the supplies should be
bypassed with a 0.1µF ceramic capacitor very close to the
supply pins, and a 4.7µF tantalum capacitor fairly close, to
handle the high current surges. While a ground plane is
recommended, the amplifier will work well with a “star”
grounding scheme. The pin 3 ground is only used for the
11
EL4390
FIGURE 3.
internal bias generator and the reference for the TTL
compatible “HOLD” input.
As with all current feedback capacitors, all stray capacitance
to the inverting inputs should be kept as low as possible, to
avoid unwanted peaking at the output. This is especially true
if the value of R
bandwidth of the part, while tolerating some peaking. In this
situation, additional capacitance on the inverting input can
lead to an unstable amplifier.
Since there are three amplifiers all in one package, and each
amplifier can sink or source typically more than 70mA, some
care is needed to avoid excessive die temperatures.
Sustained, DC currents, of over 30mA, are not
recommended, due to the limited current handling capability
of the metal traces inside the IC. Also, the short circuit
F
has already been reduced to raise the