uaa3515a NXP Semiconductors, uaa3515a Datasheet - Page 15

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

Philips Semiconductors
7.6
This section covers the TX audio path from pins MICI to
TXO (see Fig.8). The input signal at pin MICI is
AC-coupled. There is another AC-coupling at the
microphone amplifier output.
The microphone amplifier is an inverting operational
amplifier whose gain can be set by external resistors. The
non-inverting input is connected to the internal reference
voltage VB. External resistors are used to set the gain and
frequency response.
2002 Sep 09
900 MHz analog cordless telephone IC
RX gain adjusted to 0 dB.
No external resistor.
VCTL = 00.
EXP
out
TX baseband
= 7 dB at THD < 4%.
handbook, halfpage
V o(EARO)
(dBV)
20
20
40
60
0
Fig.7 Expander characteristic.
40
30
15
The TX baseband has a compressor with the
characteristic shown in Fig.9. The ALC provides a ‘soft’
limit to the output signal swing as the input voltage
increases slowly (i.e. a sine wave is maintained at the
output). A hard limiter clamps the compressor output
voltage at 1.26 V (peak-to-peak). The ALC and the hard
limiter can be disabled via the microcontroller interface.
The hard limiter is followed by a mute circuit. The TX gain
is digitally programmable in 32 steps of 0.5 dB.
y = 2
20
20
10
V i(RXAI) (dBV)
FCA168
0
Product specification
UAA3515A