U2759B Datasheet, PDF (3/9 Pages) TEMIC Semiconductors – IF Signal Processing for DAB

U2759B
Pin Description for DIP16
IF1IN
The input voltage is fed via Pins 1 and 16 to the first stage
of the 3 stage gain-controlled wide-band amplifier. The
W ^{first stage has an internal dc voltage supply with an}
internal resistance of 2 k to connect the SAW filters
directly.
AGCPRE
Pin 3 is an open-collector output. Depending on the input
level, a control voltage can be generated for the external
pre-stage by using an external voltage divider. This
prevents an overdrive of input IF1. The threshold for
activation of the open-collector output is adjusted with
Pin 2.
9229
1 _{1.2 kW}
1.2 kW
16
3
3 kW
3 kW
9227
Figure 4.
THRPRE
The control of a pre-stage can be adjusted at Pin 2 by using
an external potentiometer switched against ground. With
increasing voltage at Pin 2, control of the (external) pre-
stage does not become active until there is a high input
level at IF1. If Pin 2 is not connected, the control only
becomes active if the input is overdriven.
Figure 6.
IF2OUT
The product of input signal IF1 and the oscillator
frequency (Pins 8 and 9) can be found at Pin 6. Here it
concerns the emitter follower output with integrated
current sink. The output voltage IF2 is twice as high as the
difference between the voltage at Pin 10 and Pin 11.
6
3 kW
2
2 kW
9228
Figure 5.
9242
Figure 7.
TELEFUNKEN Semiconductors
3 (9)
Rev. A1, 06-Sep-96
Preliminary Information