Philips Semiconductors
FM/IF amplifier/demodulator circuit
Product specification
TDA1576
handbook, full pagewidth
33 pF
3
4
TDA1576
560
pF
6
7
9
8
33 pF
(1)
39 pF
(1)
L1
1 kΩ
560
pF
L2
390 Ω
39 pF
MGE457
C8-9
VoAF
Adjustment of the demodulator circuit is obtained with an IF signal which is higher than the 3 dB limiting level; L2 should be short-circuited or detuned;
L1 should be adjusted to minimum d2 distortion, and then L2 to minimum d2 distortion.
(1) Coil data: L1 = L2 = 0.38 µH; Qo = 70; coil former KAN (C).
Fig.11 An example of the TDA1576 when using a demodulator with two tuned circuits.
handbook, full pagewidth
0.3
THD
(%)
0.2
MGE467
0.1
−75
−50
−25
0
+25
+50
+75
(fo = 10.7 MHz)
∆f (kHz)
Fig.12 Total harmonic distortion as a function of detuning; fm = 400 Hz; C8−9 = 6.8 nF; ∆f = ±75 kHz; Vo = 330 mV
for a frequency deviation ∆f = ±75 kHz.
1998 Nov 18
11