OPA2375IPWR datasheet(33/51 Pages) TI1

33 / 51 page

(Standard Value)

(

)

100

: u

3.18

3.3

(Standard Value)

kHz

: u

10.11

78.7

200

: u

78.7

(closest standard value)

126

OPA

: o

126

7.93

OUT

RMS

OPA

RMS

OUT

u ¨

OPA375, OPA2375

www.ti.com

SBOS886B – NOVEMBER 2017 – REVISED JANUARY 2020

Product Folder Links: OPA375 OPA2375

Submit Documentation Feedback

Single-Supply Electret Microphone Preamplifier With Speech Filter (continued)

9.2.2 Detailed Design Procedure

The transfer function defining the relationship between VOUT and the AC input signal is shown in Equation 1.

(1)

The required gain can be calculated based on the expected input signal level and desired output level as shown

in Equation 2.

(2)

Select a standard 10-kΩ feedback resistor and calculate RG from Equation 3.

(3)

To minimize the attenuation in the desired passband from 300 Hz to 3 kHz, set the upper (fH) and lower (fL) cutoff

frequencies outside of the desired bandwidth as:

fL = 200 Hz

(4)

and

fH = 5 kHz

(5)

Select CG to set the fL cutoff frequency using Equation 6.

(6)

Select CF to set the fH cutoff frequency using Equation 7.

(7)

The input signal cutoff frequency must be set low enough such that low-frequency sound waves still pass

through. Therefore select CIN to achieve a 30-Hz cutoff frequency (fIN) using Equation 8.

(8)

The measured transfer function for the microphone preamplifier circuit is shown in Figure 86 and the measured

THD + N performance of the microphone preamplifier circuit is shown in Figure 87.

OPA2375IPWR Datasheet(PDF) 33 Page - Texas Instruments

OPA2375IPWR Datasheet(HTML) 33 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 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51

Datasheet Download

Link URL