UTCTDA2030 LINEAR INTEGRATED CIRCUIT

11

QW-R107-004,B

m2

m1

SR(V/

µs)

Input

Signal

Filtered

Output

Siganal

Fig.23 20kHz sawtooth waveform

Fig.24 Inverting sawtooth waveform

The result is an AC signal at the output whole peak-to-peak value is the TIM voltage, which can be measured

easily with an oscilloscope. If the peak-topeak value of the signal and the peak-to-peak of the inverting sawtooth are

measured, the TIM can be found very simply from:

TIM

VOUT

Vsawtooth

* 100

=

10

-1

10

0

10

1

10

2

10

-2

10

-1

10

0

10

1

UTC2030A

BD908/907

Gv=26dB

Vs=36V

RL=4

Ω

RC Filter fc=30kHz

Fig. 25 TIM distortion Vs.

Output Power

Po(W)

TIM(%)

10

-1

10

0

10

1

10

2

Vo(Vp-p)

10

-1

10

0

10

1

10

2

RC Filter fc=30kHz

Fig. 26 TIM design

diagram(fc=30kHz)

SR(V/ s)

米

In Fig.25 The experimental results are shown for the 30W amplifier using the UTC2030A as a driver and a

low-cost complementary pair. A simple RC filter on the input of the amplifier to limit the maximum signal slope(SS) is

an effective way to reduce TIM.

The Diagram of Fig.26 originated by SGS can be used to find the Slew-Rate(SR) required for a given output power

or voltage and a TIM design target.

For example if an anti-TIM filter with a cutoff at 30kHz is used and the max. Peak to peak output voltage is 20V then,

referring to the diagram, a Slew-Rate of 6V/

µs is necessary for 0.1% TIM.

As shown Slew-Rates of above 10V/

µs do not contribute to a further reduction in TIM.

Slew-Rates of 100V/

µs are not only useless but also a disadvantage in hi-fi audio amplifiers because they tend to

turn the amplifier into a radio receiver.

POWER SUPPLY

Using monolithic audio amplifier with non regulated supply correctly. In any working case it must provide a supply

voltage less than the maximum value fixed by the IC breakdown voltage.