SN10501DBVR datasheet(14/23 Pages) TI

14 / 23 page

SN10501

SN10502

SN10503

SLOS408A − MARCH 2003 − REVISED DECEMBER 2003

www.ti.com

APPLICATION CIRCUITS

Active Filtering With the SN1050x

High-frequency active filtering with the SN1050x is

achievable due to the amplifier’s high slew rate, wide

bandwidth, and voltage feedback architecture. Several

options are available for high-pass, low-pass, bandpass,

and bandstop filters of varying orders. A simple two-pole

low pass filter is presented here as an example, with two

poles at 25 MHz.

49.9

Ω

Ω Source

1.3 k

Ω

4.7 pF

5 V

−5 V

33 pF

1.3 k

Ω

52.3

Ω

Figure 45. A Two-Pole Active Filter With Two

Poles Between 90 MHz and 100 MHz

Driving Capacitive Loads

One of the most demanding, and yet very common, load

conditions for an op amp is capacitive loading. Often, the

capacitive load is the input of an A/D converter, including

additional

external

capacitance,

which

may

recommended to improve A/D linearity. A high-speed, high

open-loop gain amplifier like the SN1050x can be very

susceptible to decreased stability and closed-loop

response peaking when a capacitive load is placed directly

on the output pin. When the amplifier’s open-loop output

resistance is considered, this capacitive load introduces

an additional pole in the signal path that can decrease the

phase margin. When the primary considerations are

frequency response flatness, pulse response fidelity, or

distortion, the simplest and most effective solution is to

isolate the capacitive load from the feedback loop by

inserting a series isolation resistor between the amplifier

output and the capacitive load. This does not eliminate the

pole from the loop response, but rather shifts it and adds

a zero at a higher frequency. The additional zero acts to

cancel the phase lag from the capacitive load pole, thus

increasing the phase margin and improving stability.

Power Supply Decoupling Techniques and

Recommendations

Power supply decoupling is a critical aspect of any

high-performance amplifier design process. Careful

decoupling provides higher quality ac performance (most

notably improved distortion performance). The following

guidelines ensure the highest level of performance.

Place decoupling capacitors as close to the power

supply inputs as possible, with the goal of minimizing

the inductance of the path from ground to the power

supply.

Placement priority should put the smallest valued

capacitors closest to the device.

Use

solid

power

and

ground

planes

recommended to reduce the inductance along power

supply return current paths, with the exception of the

areas underneath the input and output pins.

Recommended values for power supply decoupling

include a bulk decoupling capacitor (6.8 to 22

µF), a

mid-range decoupling capacitor (0.1

µF) and a high

frequency decoupling capacitor (1000 pF) for each

supply. A 100 pF capacitor can be used across the

supplies as well for extremely high frequency return

currents, but often is not required.

SN10501DBVR Datasheet(PDF) 14 Page - Texas Instruments

SN10501DBVR Datasheet(HTML) 14 Page - Texas Instruments

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

Datasheet Download

Link URL