Philips Semiconductors
Versatile telephone transmission circuit
with dialler interface
Product specification
TEA1068
handbook, full pagewidth
QR+
QR−
VEE
QR+
QR−
(1)
QR+
QR−
a. Dynamic earpiece
with less than 450 Ω
impedance.
b. Dynamic earpiece with
more than 450 Ω
impedance.
c. Magnetic earpiece
with more than 450 Ω
impedance.
(2)
QR+
QR−
MBH136
d. Piezoelectric
earpiece.
(1) May be connected to prevent distortion (inductive load).
(2) Required to increase the phase margin (capacitive load).
Fig.12 Alternative receiver arrangements.
dbook, full pagewidth
0
∆Gv
(dB)
−2
R6 = ∞
MBH137
−4
48.7 kΩ 78.7 kΩ 110 kΩ 140 kΩ
−6
0
20
40
60
80
100
120
140
Iline(mA)
R9 = 20 Ω.
1996 Apr 23
Fig.13 Variation of gain with line current, with R6 as a parameter.
14