EL2045

FN7030 Rev 1.00

Page 7 of 10

February 11, 2005

Simplified Schematic

Burn-In Circuit

Applications Information

Product Description

The EL2045 is a low-power wideband, gain-of-2 stable

monolithic operational amplifier built on Elantec's proprietary

high-speed complementary bipolar process. The EL2045

uses a classical voltage-feedback topology which allows it to

be used in a variety of applications where current-feedback

amplifiers are not appropriate because of restrictions placed

upon the feedback element used with the amplifier. The

conventional topology of the EL2045 allows, for example, a

capacitor to be placed in the feedback path, making it an

excellent choice for applications such as active filters,

sample-and-holds, or integrators. Similarly, because of the

ability to use diodes in the feedback network, the EL2045 is

an excellent choice for applications such as fast log

amplifiers.

Single-Supply Operation

The EL2045 has been designed to have a wide input and

output voltage range. This design also makes the EL2045 an

excellent choice for single-supply operation. Using a single

positive supply, the lower input voltage range is within

range is within 300mV of ground. Upper input voltage range

reaches 4.2V, and output voltage range reaches 3.8V with a

swing on a single 5V supply. This wide output voltage range

also allows single-supply operation with a supply voltage as

high as 36V or as low as 2.5V. On a single 2.5V supply, the

EL2045 still has 1V of output swing.

Gain-Bandwidth Product and the -3dB Bandwidth

The EL2045 has a gain-bandwidth product of 100MHz while

using only 5.2mA of supply current. For gains greater than 4,

its closed-loop -3dB bandwidth is approximately equal to the

gain-bandwidth product divided by the noise gain of the

circuit. For gains less than 4, higher-order poles in the

amplifier's transfer function contribute to even higher closed

loop bandwidths. For example, the EL2045 has a -3dB

bandwidth of 100MHz at a gain of +2, dropping to 20MHz at

a gain of +5. It is important to note that the EL2045 has been

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