FEATURES

MINIMAL BANDWIDTH CHANGE VERSUS GAIN

170MHz BANDWIDTH AT G = +2

> 120MHz BANDWIDTH TO GAIN > +10

LOW DISTORTION: < –82dBc at 5MHz

HIGH OUTPUT CURRENT: 120mA

SINGLE +5V TO +12V SUPPLY OPERATION

DUAL ±2.5 TO ±6.0V SUPPLY OPERATION

LOW SUPPLY CURRENT: 3.4mA Total

APPLICATIONS

SHORT-LOOP ADSL CO DRIVER

LOW-POWER BROADCAST VIDEO DRIVERS

DIFFERENTIAL EQUALIZING FILTERS

DIFFERENTIAL SAW FILTER POST AMPLIFIER

MULTICHANNEL SUMMING AMPLIFIERS

PROFESSIONAL CAMERAS

ADC INPUT DRIVERS

DESCRIPTION

The OPA2684 provides a new level of performance in lowpower,

wideband, current-feedback (CFB) amplifiers. This

CFBPLUS amplifier is among the first to use an internally

closed-loop input buffer stage that enhances performance

significantly over earlier low-power CFB amplifiers. While

retaining the benefits of very low power operation, this new

architecture provides many of the benefits of a more ideal

CFB amplifier. The closed-loop input stage buffer gives a

very low and linearized impedance path at the inverting input

to sense the feedback error current. This improved inverting

input impedance retains exceptional bandwidth to much

higher gains and improves harmonic distortion over earlier

solutions limited by inverting input linearity. Beyond simple

high-gain applications, the OPA2684 CFBPLUS amplifier permits

the gain setting element to be set with considerable

freedom from amplifier bandwidth interaction. This allows

frequency response peaking elements to be added, multiple

input inverting summing circuits to have greater bandwidth,

and low-power line drivers to meet the demanding requirements

of studio cameras and broadcast video.

The output capability of the OPA2684 also sets a new mark

in performance for low-power, current-feedback amplifiers.

Delivering a full ±4Vp-p swing on ±5V supplies, the OPA2684

also has the output current to support > ±3Vp-p into 50Ω

loads. This minimal output headroom requirement is complemented

by a similar 1.2V input stage headroom giving

exceptional capability for single +5V operation.

The OPA2684’s low 3.4mA supply current is precisely trimmed

at +25°C. This trim, along with low shift over temperature and

supply voltage, gives a very robust design over a wide range

of operating conditions.