EL2030
In addition, the EL2030 will be destroyed or damaged in the
Burn-In Circuit
same way for momentary power supply voltage reversals.
This could happen, for example, during a power turn on
transient, or if the power supply voltages were oscillating and
the positive rail were instantaneously negative with respect
to the negative rail or vice versa.
Differential Gain and Differential Phase
Composite video signals contain intensity, color, hue, timing
and audio information in AM, FM, and Phase Modulation.
These video signals pass through many stages during their
production, processing, archiving and transmission. It is
important that each stage not corrupt these signals to
provide a “high fidelity” image to the end viewer.
ALL PACKAGES USE THE SAME
SCHEMATIC
An industry standard way of measuring the distortion of a
video component (or system) is to measure the amount of
differential gain and phase error it introduces. A 100mV peak
to peak sine wave at 3.58MHz for NTSC (4.3MHz for PAL),
with 0V DC component serves as the reference. The
reference signal is added to a DC offset, shifting the sine
wave from 0V to 0.7V which is then applied to the device
under test (DUT). The output signal from the DUT is
compared to the reference signal. The Differential Gain is a
measure of the change in amplitude of the sine wave and is
measured in percent. The Differential Phase is a measure of
the change in the phase of the sine wave and is measured in
degrees. Typically, the maximum positive and negative
deviations are summed to give peak differential gain and
differential phase errors. The test setup in Figure 1 was used
to characterize the EL2030. For higher than NTSC and PAL
frequencies, an alternate Differential Gain and Phase
measurement can be made using an HP3577A Network
Analyzer and the setup shown in Figure 2. The frequency
response is normalized to gain or phase with 0V DC at the
input. From the normalized value a DC offset voltage is
introduced and the Differential Gain or Phase is the deviation
from the normalized value.
Test Circuit
Application Information
Product Description
The EL2030 is a current mode feedback amplifier similar to
the industry standard EL2020, but with greatly improved AC
characteristics. Most significant among these are the
extremely wide bandwidth and very low differential gain and
phase. In addition, the EL2030 is fully characterized and
tested at ±5V and ±15V supplies.
Power Supply Bypassing/Pin Dressing
Video Applications
It is important to bypass the power supplies of the EL2030
with 0.1µF ceramic disc capacitors. Although the pin length
is not critical, it should not be more the 1/2 inch from the IC
pins. Failure to do this will result in oscillation, and possible
destruction of the part. Another important detail is the pin
length of the inputs. The inputs should be designed with
minimum stray capacitance and short pin lengths to avoid
ringing and distortion.
The video signals that must be transmitted for modest
distances are usually amplified by a device such as the
EL2030 and carried via coax cable. There are at least two
ways to drive cables, single terminated and double
terminated.
When driving a cable, it is important to terminate it properly
to avoid unwanted signal reflections. Single termination (75Ω
to ground at receive end) may be sufficient for less
demanding applications. In general, a double terminated
cable (75Ω in series at drive end and 75Ω to ground at
receive end) is preferred since the impedance match at both
ends of the line will absorb signal reflections. However, when
double termination is used (a total impedance of 150Ω), the
received signal is reduced by half; therefore, the amplifier is
usually set at a gain of 2 or higher to compensate for
attenuation.
Latch Mode
The EL2030 can be damaged in certain circumstances
resulting in catastrophic failure in which destructive supply
currents flow in the device. Specifically, an input signal
greater than ±5 volts at currents greater than 5mA is applied
to the device when the power supply voltages are zero will
result in failure of the device.
9
INTERSIL [ Intersil ]
