SAN2202

6/9

sames

sames

sames

sames

8.1 Frequency response

Fig.

2

shows

the

frequency

response curve of the loudspeaker

amplifier. The curve shows the

output level on an 8

Ω resistor

(solid line) and an 8

Ω loudspeaker

(dotted

line;

PHILIPS

AD3371

series

80mm

∅

8

Ω

speaker)

measured with maximum volume

and

-10dBm Rx level on line. The peak

at 200Hz is a resonant frequency

of the specific loudspeaker type.

Gain of the amplifier is set by the

resistors R6 and the attenuation of

VR1. The bandwidth is adjusted by

CC4.

8.2 maximum sending level

Fig.3

shows

the

maximum

Transmit sending level, measured

at LI vs. line current, assuming a

total harmonic distortion (THD) of

less than 1%.

AN2201a (dotted line): At line

currents >40mA, VPP will rise up to

2.5V (@ 90mA) and sending level

will be slightly distorted before it

reaches the soft clip level (

± 2V

peak

) .

AN2202b (solid line):There is no

influence

in

maximum

sending

level, the transmit signal can be up

to the soft clip level at line currents

of >12mA.

Fig. 3: maximum sending level vs. line current (@ THD <1%)

8.3 maximum output power

Fig.4 and Fig.5 show the maximum output power on an 8

Ω loudspeaker at f=1kHz: the curves indicate the

maximum output power with <2% and <3% total harmonic distortion.

SAN2202a: The lower output drive capability at higher line currents results from nonlinearities at higher collector

currents and mismatch in the complementary transistor types.

SAN2202b: Maximum output power is not decreased with higher line currents.

8 Measurement results & curves

Frequency response of LS-Amplifier

-18

-17

-16

-15

-14

-13

-12

100

1000

10000

f [Hz]

8 Ohm Resistor

8 Ohm Loudspeaker

max. sending level @ THD <1%

2,6

2,8

3

3,2

3,4

3,6

3,8

4

4,2

4,4

15

20

25

30

35

40

45

50

55

60

Line current [mA]

SAN2202a

SAN2202b