TEA1110A

LINEAR INTEGRATED CIRCUIT

UNISONICTECHNOLOGIESCO.,LTD

9 of 9

www.unisonic.com.tw

QW-R108-014.C

FUNCTIONAL DESCRIPTION(Cont.)

SIDETONE SUPPRESSION

Fig.6) suppresses the transmitted signal in the earpiece. Maximum compensation is obtained under the following

conditions:

)

R

×

1

Rast

(

))

R

+

3

Rast

(

×

2

Rast

(

=

K

SLPE

SLPE

Zbal= k×ZIine

The scale factor k is mainly for the compatibility with a standard capacitor from the E6 or E12 range for Zbal.

Zline varies considerably with the line type and the line length in practice. Therefore, the Zbal value should be

set to be an average line length which gives appropriate side tone suppression with short and long lines. The

suppression also depends on the accuracy of the match between Zbaland the impedance of the average line.

The receiving signal is to be attenuated 32dB by the anti-side tone network from the line before it enters the

receiving amplifier, and the attenuation is almost constant over the whole audio frequency range.

Im

Zbal

SLPE

IR

Zline

LN

Zir

Fig.6 Equivalent circuit of UTC TEA1110A anti-sidetone bridge

UTC assumes no responsibility for equipment failures that result from using products at values that

exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or

other parameters) listed in products specifications of any and all UTC products described or contained

herein. UTC products are not designed for use in life support appliances, devices or systems where

malfunction of these products can be reasonably expected to result in personal injury. Reproduction in

whole or in part is prohibited without the prior written consent of the copyright owner. The information

presented in this document does not form part of any quotation or contract, is believed to be accurate

and reliable and may be changed without notice.