U2514B-AFNG3 TEMIC [TEMIC Semiconductors], U2514B-AFNG3 Datasheet - Page 3

• Manufacturer Part Number: U2514B-AFNG3
• Description: AM/FM Receiver for Digital Tuning with FM-Stereo Decoder
• Manufacturer: TEMIC [TEMIC Semiconductors]

TELEFUNKEN Semiconductors
Rev. A2, 04-Nov-96
Pin Description
FMIN, FMAGC, FMRF
The FM pre-amplifier input FMIN (Pin 28) consists of a
transistor grounded base circuit (T
excellent noise performance and large signal behavior. It
is recommended to connect a source impedance of 100
in order to achieve optimal performance. The dc current
through the amplifying transitor is reduced by the internal
AGC. This means in the case of large input signals, the
input ac current is bypassed via the wideband AGC
transistor T
(Pin 2) and GNDRF (Pin 4). It shortens the transistor base
to GNDRF and it also serves for smoothing of the AGC
voltage. A tuned RF circuit is connected between FMRF
(Pin 3) and VS (Pin 27). The amplified RF signal is fed
internally to the mixer input.
VREF
FMIN
28
1
. A capacitor is connected between FMAGC
T
1
3
Figure 3.
T
GNDRF
2
FMRF
1.5 k
Preliminary Information
2
) which provides
I
AGC
MIXER
FMAGC
FM
2
12414
ON
W
FMOSCE, FMOSCB
The FM local oscillator consists of a transistor in
grounded
resistance at the base of the transistor is generated by an
external capacitor connected between emitter FMOSCE
(Pin 5) and GNDRF (Pin 4) An other external capacitor
is connected between base FMOSCB (Pin 6) and emitter
FMOSCE (Pin 5) which increases the resistance at the
emitter and leads to a higher oscillator swing. The
negative resistance at FMOSCB is approximately 250
Therefore, the resonant LO tank resistance of
approximately 5 k
transformed to this magnitude via a capacitor.
OSCOUT
A resistor is connected between OSCOUT (Pin 8) and
VREF (Pin 14). It determines the amplitude of oscillator
voltage which is fed to the PLL circuit. The TEMIC PLL
familiy U428xBM is recommended because it offers high
signal to noise ratio and low current consumption.
FMOSCB
FMOSCE
6
5
collector
FM
W
(depends on Q-factor of the coil) is
Figure 4.
Figure 5.
configuration.
8
GNDRF
OSCOUT
1.2 k
U2514B
12416
AM
The
FM
negative
12415
3 (15)
ON
W
.