4423

SBFS020A − JANUARY 1978 − REVISED JUNE 2004

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5

EXTERNAL CONNECTIONS

20kHz Quadrature Oscillator

The 4423 does not require any external component to

obtain a 20kHz quadrature oscillator. The connection

diagram is shown in Figure 4.

+15V

E

E

−15V

10

2

8

1

7

13

11

9

4423

Figure 4.

Resistor-Programmable Quadrature Oscillator

For resistor-programmable frequencies in the 2kHz to

20kHz frequency range, the connection diagram is

provided in Figure 5. Note that only two resistors of

equal value are required. Resistor R can be expressed

by Equation (1).

R

+ 3.785f

42.05

* 2f

Where:

R is in k

Ω,

f is in kHz.

+15V

E

RR

E

−15V

10

2

8

1

7

13

11

3

12

9

4423

Figure 5.

Quadrature Oscillator Programmable to 0.002Hz

For oscillator frequencies below 2kHz, the use of two

capacitors of equal value is recommended, as shown in

Figure 6.The connections shown in Figure 6 can be

used to obtain oscillator frequency outputs in the

0.002Hz to 20kHz range.

+15V

E

E

−15V

10

12

3

1

7

14

1

1

2

13

9

4423

8

R

C

C

R

Figure 6.

Frequency f can be expressed by Equation (2).

f

+

42.05R

(C

) 0.001)(3.785 ) 2R)

Where:

f is in Hz.

C is in

µF.

R is in k

Ω.

For best results, the capacitor values shown in Table 1

should be selected with respect to their frequency

ranges.

Table 1. Recommended Capacitor Values

f

20kHz

to

2kHz

2kHz

to

200Hz

200Hz

to

20Hz

C

0

0.01

µF

0.1

µF

20Hz

to

2Hz

2Hz

to

0.2Hz

0.2Hz

to

0.02Hz

0.02Hz

to

0.002Hz

1

µF

10

µF

100

µF

1000

µF

(1)

(2)