Philips Semiconductor

Product data

NE5517/NE5517A/

AU5517

Dual operational transconductance amplifier

2002 Dec 06

10

V+

11

D4

Q6

Q7

2,15

D2

Q4

Q5

D3

–INPUT

4,13

+INPUT

3,14

AMP BIAS

INPUT

1,16

Q2

Q1

D1

V–

6

Q10

D6

Q11

VOUTPUT

5,12

Q9

Q8

D5

Q14

Q15

Q16

R1

D7

D8

Q3

7,10

Q12

Q13

8,9

SL00313

Figure 8. Circuit Diagram of NE5517

+VS

ID

IB

I5

Q4

1/2ID

IS

IS

1/2ID

–VS

I4

I5

D3

D2

I

D

2

* I

S

I

D

2

) I

S

I

0 +

I

5 *

I

4

I

0 +

2I

S

I

B

I

D

SL00314

Figure 9. Linearizing Diode

Stereo Amplifier With Gain Control

Figure 11 shows a stereo amplifier with variable gain via a control

input. Excellent tracking of typical 0.3 dB is easy to achieve. With

amplifiers, the potentiometer may be replaced with two 510

Ω

resistors.

Modulators

Because the transconductance of an OTA (Operational

amplification of a signal can be controlled easily. The output current

is the product from transconductance

×input voltage. The circuit is

effective up to approximately 200 kHz. Modulation of 99% is easy to

achieve.

Voltage-Controlled Resistor (VCR)

Because an OTA is capable of producing an output current

proportional to the input voltage, a voltage variable resistor can be

made. Figure 13 shows how this is done. A voltage presented at the

R

) R

A

gM

) R

A

Figure 14 shows a Voltage Controlled Resistor using linearizing

diodes. This improves the noise performance of the resistor.

Voltage-Controlled Filters

Figure 15 shows a Voltage Controlled Low-Pass Filter. The circuit is

response rolls off at a 6dB per octave with the –3 dB point being

defined by the given equations. Operating in the same manner, a

Voltage Controlled High-Pass Filter is shown in Figure 16. Higher

order filters can be made using additional amplifiers as shown in

Figures 17 and 18.

Voltage-Controlled Oscillators

Figure 19 shows a voltage-controlled triangle-square wave

generator. With the indicated values a range from 2 Hz to 200 kHz is

Please notice the differential input voltage is not allowed to be above

5 V.

With a slight modification of this circuit you can get the sawtooth

pulse generator, as shown in Figure 20.