SA572

http://onsemi.com

6

Buffer Amplifier

In audio systems, it is desirable to have fast attack time

and slow recovery time for a tone burst input. The fast

attack time reduces transient channel overload but also

causes low-frequency ripple distortion. The low-frequency

ripple distortion can be improved with the slow recovery

time. If different attack times are implemented in

corresponding frequency spectrums in a split band audio

system, high quality performance can be achieved. The

buffer amplifier is designed to make this feature available

with minimum external components. Referring to

Figure 5, the rectifier output current is mirrored into the

positive-going input signal, the buffer amplifier acts like a

insignificant. Neglecting diode impedance, the gain Ga(t)

for

DG can be expressed as follows:

*t

tA

where

*t

tR

*t

tR

where

internal resistor. The gain control current is mirrored to the

X2

X2

A3

TRACKING

TRIM

V+

IR +

VIN

R

−

+

Figure 5. Buffer Amplifier Schematic

10kW

10kW