7

Applications Information

The EL2120 represents the third generation of current-

feedback amplifier design. It is designed to provide good

high-frequency performance over wide supply voltage, load

impedance, gain, temperature, and manufacturing lot

variations. It is a well-behaved amplifier in spite of its

100MHz bandwidth, but a few precautions should be taken

to obtain maximum performance.

The power supply pins must be well bypassed. 0.01µF

ceramic capacitors are adequate, but lead length should be

kept below 1/4” and a ground plane is recommended.

Bypassing with 4.7µF tantalum capacitors can improve

settling characteristics, and smaller capacitors in parallel will

not be needed. The lead length of sockets generally

deteriorates the amplifier's frequency response by

exaggerating peaking and increasing ringing in response to

transients. Short sockets cause little degradation.

Load capacitance also increases ringing and peaking.

Capacitance greater than 35pF should be isolated with a

similar effect, and should be kept below 5pF. Often, the

inductance of the leads of a load capacitance will be self-

resonant at frequencies from 40MHz to 200MHz and can

cause oscillations. A resonant load can be de-Q'ed with a

small series or parallel resistor. A “snubber” can sometimes

Enable Response for

a Family of Inputs

Disable Response for

a Family of Inputs

Supply Current vs

Supply Voltage

8-Pin Plastic DIP

Maximum Power Dissipation

vs Ambient Temperature

8-Pin SO

Maximum Power Dissipation

vs Ambient Temperature

EL2120