Datasheet

TEF6901A_3 © NXP B.V. 2008. All rights reserved.
Product data sheet Rev. 03 — 20 March 2008 7 of 107
NXP Semiconductors
TEF6901A
Integrated car radio
7. Functional description
7.1 FM mixer 1
The FM quadrature mixer 1 converts FM RF (65 MHz to 108 MHz) to an IF frequency of
10.7 MHz. The FM mixer provides image rejection and a large dynamic range. Low and
high injection Local Oscillator (LO) can be selected via the I
2
C-bus.
7.2 FM RF AGC
AGC detection at the FM front-end mixer input with programmable threshold. When the
threshold is exceeded, the PIN diode drive circuit sources a current to an external PIN
diode circuit, keeping the RF signal level constant. Keyed AGC function is selectable via
the I
2
C-bus and uses the in-band level information derived from the limiter. The AGC PIN
diode drive circuit can optionally deliver a fixed current; this local mode can be used for
search tuning on absolute RF levels. In AM mode, the FM AGC PIN diode drive circuit can
be set to source a fixed current into the external FM PIN diode circuitry.
7.3 FM mixer 2
The FM quadrature mixer 2 converts 10.7 MHz IF1 to 450 kHz IF2 and includes image
rejection with the integrated channel filter. Two gain settings can be selected to
compensate for high ceramic filter insertion loss.
7.4 FM IF2 channel filter
The order and dynamic range of the FM IF2 channel filter is designed for operation with
only one external ceramic filter. The filter characteristic is optimized to combine high
selectivity with low distortion. The bandwidth of the filter can be set to a range of fixed
settings or automatically via the bandwidth control algorithm. When the automatic mode is
selected the bandwidth depends on the signal conditions.
IND 52 audio input D, signal input
INC 53 audio input C, common mode or signal input
INBR 54 audio input B, right channel
INBL 55 audio input B, left channel
INAC 56 audio input A, left channel inverted (or other options)
INAR 57 audio input A, right channel
INAL 58 audio input A, left channel
MPXAMIN 59 MPX and AM audio input to radio processing
MPXAMOUT 60 MPX and AM audio output from tuner part
VCCVCO 61 Voltage-Controlled Oscillator (VCO) supply voltage
VCOFDB 62 VCO feedback
VCOTNK 63 VCO tank circuit
VCOGND 64 VCO ground
Table 3. Pin description
…continued
Symbol Pin Description