uaa3515a NXP Semiconductors, uaa3515a Datasheet - Page 14

• Manufacturer Part Number: uaa3515a
• Description: 900 Mhz Analog Cordless Telephone Ic
• Manufacturer: NXP Semiconductors

Philips Semiconductors
7.5
This section covers the RX audio path from pins RXAI to
EARO (see Fig.6). The RXAI input signal is AC-coupled.
The microcontroller sets the value of the RX gain in
32 linear steps of 0.5 dB. The RX baseband has a mute
function and an expander with characteristics as shown in
Fig.7.
For audio level adjustment and, potentially for software
volume control, setting the RX gain provides a dynamic
range of 31 dB. This is achieved by the expander slope
that multiplies the RX gain by a factor of two for each gain
step thus giving 1 dB steps measured at the earpiece
amplifier output.
2002 Sep 09
handbook, full pagewidth
900 MHz analog cordless telephone IC
Receiver baseband
UAA3515A
EXPANDER RX MUTE
Fig.6 RX baseband block diagram.
VB
R int
14
EARPIECE
AMPLIFIER
RX GAIN
The earpiece amplifier is a rail-to-rail inverting operational
amplifier. The non-inverting input is connected to the
internal reference voltage at pin VB. Software volume
control on the earpiece amplifier is achieved by using an
integrated switched feedback resistor R
control tuning range is 14 dB. Hardware volume control is
achieved by switching externally the earpiece feedback
resistor R
FCA298
46 RXAI
45 ECAP
44 V CC(ARX)
43 EARI
42 EARO
ext
C ext
.
R ext
Product specification
UAA3515A
int
. The volume