U2759B Datasheet, PDF (5/9 Pages) TEMIC Semiconductors – IF Signal Processing for DAB

U2759B
VREF
Functional Description
A stabilized voltage is available at Pin 12 on to which an
external voltage divider for supplying Pin 10 and Pin 11
can be connected.
At Pin 13, the internally generated temperature stable
reference voltage is blocked against ground. This voltage
must not be loaded by external circuitry.
More information concerning the parameters:
Noise ratio of all ICs:
Typically 11.2 dB (SSB)
Intercept point 3rd order:
Typically 58 dB (2 V_ss at Pin 6)
13
12
The U2759B consists of a controllable wideband ampli-
fier, a mixer and AGC-block.
The input voltage V_if1 is applied at Pin 1 and 16 and it is
fed via a 3-stage controlled wideband amplifier to the
mixer. The oscillator voltage can be applied symmetri-
cally as well as unsymmetrically.
The mixed signal is used in order to generate the AGC-
voltage. The mixed signal therefore is fed to a comparator
which charges or discharges an external capacitor depen-
dent on the signal level. The threshold of the comparator
can be adjusted externally. The generated voltage con-
trols the wideband amplifier.
The generated control voltage can be used also for an
additional external preamplifier. This AGC protects the
IF1 input against overload.
The amplitude as well as the superimposed DC-level of
the output voltage V_IF2 can be adjusted by an external
voltage. V_REF is therefore available at Pin 12 (max.
500 mA).
Upper limiting threshold
4.5 V
9246
Figure 12.
DC-level
(Pin 11)
V_P (Pin 6)
IF AGC threshold
(Pin 10)
1.7 V
Lower limiting threshold
12586
Figure 13. Adjustment of output level
TELEFUNKEN Semiconductors
5 (9)
Rev. A1, 06-Sep-96
Preliminary Information