300

+3V

150

R

1

(1)

2V – DV

2V + DV

NOTE: (1) R

only for low voltage operation — see text.

3V

R

G

INA118

V

O

Ref

INA118

www.ti.com

SBOS027A – SEPTEMBER 2000 – REVISED JANUARY 2016

Single Supply Operation (continued)

Figure 35. Single-Supply Bridge Amplifier

10 Layout

10.1 Layout Guidelines

TI always recommends paying attention to good layout practices. For best operational performance of the device,

use good printed-circuit-board (PCB) layout practices, including:

•

Take care to ensure that both input paths are well-matched for source impedance and capacitance to avoid

converting common-mode signals into differential signals. In addition, parasitic capacitance at the gain-setting

pins can also affect CMRR over frequency. For example, in applications that implement gain switching using

switches or PhotoMOS® relays to change the value of RG, select the component so that the switch

capacitance is as small as possible.

•

Noise can propagate into analog circuitry through the power pins of the circuit as a whole, and of the device

itself. Bypass capacitors are used to reduce the coupled noise by providing low-impedance power sources

local to the analog circuitry. Connect low-ESR, 0.1-

μF ceramic bypass capacitors between each supply pin

applicable for single-supply applications.

•

Separate grounding for analog and digital portions of the circuitry is one of the simplest and most effective

methods of noise suppression. One or more layers on multilayer PCBs are usually devoted to ground planes.

A ground plane helps distribute heat and reduces EMI noise pickup. Make sure to physically separate digital

and analog grounds, paying attention to the flow of the ground current. For more detailed information, see

Circuit Board Layout Techniques (SLOA089).

•

To reduce parasitic coupling, run the input traces as far away from the supply or output traces as possible. If

these traces cannot be kept separate, crossing the sensitive trace perpendicular is much better than in

parallel with the noisy trace.

•

Keep the traces as short as possible.

Copyright © 2000–2016, Texas Instruments Incorporated

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