Power supply considerations

TSH350

12/22

4

Power supply considerations

Correct power supply bypassing is very important for optimizing performance in high-

frequency ranges. Bypass capacitors should be placed as close as possible to the IC pins to

improve high-frequency bypassing. A capacitor greater than 1

μF is necessary to minimize

the distortion. For better quality bypassing, a capacitor of 10nF can be added which should

also be placed as close as possible to the IC pins.

Bypass capacitors must be incorporated for both the negative and the positive supply.

Note:

On the SO8_SINGLE_HF board, these capacitors are C6, C7, C8, C9.

Figure 30.

Circuit for power supply bypassing

Single power supply

In the event that a single supply system is used, biasing is necessary to obtain a positive

DC component of the signal at this value. Several options are possible to provide this bias

supply, such as a virtual ground using an operational amplifier or a two-resistance divider

(which is the cheapest solution). A high resistance value is required to limit the current

consumption. On the other hand, the current must be high enough to bias the non-inverting

input of the amplifier. If we consider this bias current (35

μA maximum) as 1% of the current

through the resistance divider, to keep a stable mid-supply, two resistances of 750

Ω can be

used.

The input provides a high-pass filter with a break frequency below 10Hz which is necessary

Figure 31 illustrates a 5V single power supply configuration for the SO8_S_MULTI

evaluation board (see Evaluation boards on page 11).

+

10µF

+

10nF

10µF

+

10nF

-

+

10µF

+

10nF

10µF

+

10nF

-