OP162GSZ datasheet(15/20 Pages) AD

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OP162/OP262/OP462

Rev. F | Page 15 of 20

100

50mV

µs

VS = 5V

AV = 1

CL = 300pF

RL = 10kΩ

WITH SNUBBER:

RX = 140Ω

CX = 10nF

Figure 45 shows the worst case crosstalk between two amplifiers

in the OP462. A 1 V rms signal is applied to one amplifier while

measuring the output of an adjacent amplifier. Both amplifiers

are configured for unity gain and supplied with ±2.5 V.

FREQUENCY (Hz)

0.010

0.001

0.0001

100

10k

20k

VS = ±2.5V

AV = 1

VIN = 1.0V rms

RL = 10kΩ

BANDWIDTH:

<10Hz TO 22kHz

Figure 42. A Photo of a Nice Square Wave at the Output

The network operates in parallel with the load capacitor, CL,

and provides compensation for the added phase lag. The actual

values of the network resistor and capacitor are empirically

determined to minimize overshoot and maximize unity-gain

bandwidth. Table 6 shows a few sample snubber networks for

large load capacitors.

Figure 44. THD + N vs. Frequency

FREQUENCY (Hz)

–40

–90

–80

–70

–60

–50

–140

–130

–120

–110

–100

100

10k

20k

AV = 1

VIN = 1.0V rms

(0dBV)

RL = 10kΩ

VS = ±2.5V

Table 6. Snubber Networks for Large Capacitive Loads

CLOAD

< 300 pF

140 Ω

10 nF

500 pF

100 Ω

10 nF

1 nF

80 Ω

10 nF

10 Ω

47 nF

Higher load capacitance will reduce the unity-gain bandwidth

of the device. Figure 43 shows unity-gain bandwidth vs.

capacitive load. The snubber network does not provide any

increase in bandwidth, but it substantially reduces ringing and

overshoot, as shown between Figure 41 and Figure 42.

CLOAD

10pF

100pF

1nF

10nF

Figure 45. Crosstalk vs. Frequency

PCB LAYOUT CONSIDERATIONS

Because the OP162/OP262/OP462 can provide gains at high

frequency, careful attention to board layout and component

selection is recommended. As with any high speed application,

a good ground plane is essential to achieve the optimum

performance. This can significantly reduce the undesirable

effects of ground loops and I × R losses by providing a low

impedance reference point. Best results are obtained with a

multilayer board design with one layer assigned to ground

plane.

Use chip capacitors for supply bypassing, with one end of the

capacitor connected to the ground plane and the other end

connected within 1/8 inch of each power pin. An additional

large tantalum electrolytic capacitor (4.7 µF to 10 µF) should be

connected in parallel. This capacitor provides current for fast,

large-signal changes at the device’s output; therefore, it does not

need to be placed as close to the supply pins.

Figure 43. Unity-Gain Bandwidth vs. CLOAD

TOTAL HARMONIC DISTORTION AND CROSSTALK

The OPx62 device family offers low total harmonic distortion

making it an excellent choice for audio applications. Figure 44

shows a graph of THD plus noise figures at 0.001% for the

OP462.

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