OPA692 datasheet(23/31 Pages) BURR-BROWN

23 / 31 page

www.ti.com

GAIN ACCURACY AND LINEARITY

0.0200

0.0175

0.0150

0.0125

0.0100

0.0075

0.0050

0.0025

V (peak-to-peak)

Figure42TestCircuit

R =100W

R =500W

NOISE PERFORMANCE

700

600

500

400

300

200

100

Gain(V/V)

Mean=1.9883

=0.0967

4kT

1/3

OPA3693

4kT=1.6E

20J

at290K

4kTR

OPA3693

SBOS353 – DECEMBER 2006

much

voltage-swing-dependent

output

distortion than strictly power-dependent. To use the

500

Ω intercept curve, use the single-tone voltage

swing as if it were driving a 50

Ω load to compute the

PO used in the intercept equation.

The OPA3693 provides improved absolute gain

accuracy and dc linearity over earlier fixed gain of

two line drivers. Operating at a gain of +2V/V by

tying the –IN pin to ground, the OPA3693 shows a

maximum gain error of

±1% at +25°C. The dc gain

therefore lies between 1.98V/V and 2.02V/V at room

temperature. Over the specified temperature ranges,

this gain tolerance expands only slightly due to the

Figure 56. DC Linearity vs Output Swing and

matched temperature drift for RF and RG. Achieving

Loads

this gain accuracy requires a very low impedance

ground at –IN. Typical production lots show a much

tighter distribution in gain than this

±1% specification.

Figure 55 shows a typical distribution in measured

gain at the gain of +2V/V configuration, in this case

The OPA3693 offers an excellent balance between

showing a slight drop in the mean (0.25%) from the

voltage and current noise terms to achieve a low

nominal but with a very tight distribution.

output noise under a variety of operating conditions.

The inverting node noise current (internal) appears at

the output multiplied by the relatively low 300

Ω

feedback

resistor.

The

input

noise

voltage

(1.8nV/

√Hz) is extremely low for a unity-gain stable

amplifier. This low input voltage noise was achieved

at the price of higher noninverting input current noise

(17.8pA/

√Hz). As long as the ac source impedance

looking out of the noninverting input is less than

100

Ω, this current noise does not contribute

significantly to the total output noise. The op amp

input voltage noise and the two input current noise

terms combine to give low output noise for the each

of the three gain settings available using the

OPA3693. Figure 57 shows the op amp noise

analysis model with all of the noise terms included.

In this model, all noise terms are taken to be noise

voltage or current density terms in either nV/

√Hz or

pA/

√Hz.

Figure 55. Typical +2V/V Gain Distribution

The exceptionally linear output stage (as illustrated

by the high 3rd-order intermodulation intercept) and

low thermal gradient induced errors for the OPA3693

give an extremely linear output over large voltage

swings and heavy loads. Figure 56 shows the tested

deviation (in % of peak-to-peak) from linearity for a

range of symmetrical output swings and loads. Below

4VPP, for either a 100Ω or a 500Ω load, the

OPA3693 delivers greater than 14-bit linear output

response.

Figure 57. Op Amp Noise Model

Submit Documentation Feedback

OPA692 Datasheet(PDF) 23 Page - Burr-Brown (TI)

OPA692 Datasheet(HTML) 23 Page - Burr-Brown (TI)

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Datasheet Download

Link URL