LM13700MX National Semiconductor, LM13700MX Datasheet - Page 15

• Manufacturer Part Number: LM13700MX
• Description: IC,Operational Amplifier,DUAL,BIPOLAR,SOP,16PIN,PLASTIC
• Manufacturer: National Semiconductor

Specifications of LM13700MX

• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Voltage Controlled Filters
Voltage Controlled Oscillators
The classic Triangular/Square Wave VCO of Figure 15 is
one of a variety of Voltage Controlled Oscillators which may
be built utilizing the LM13700. With the component values
shown, this oscillator provides signals from 200 kHz to below
2 Hz as I
amplitudes are set by I
input voltage must be less than 5V to prevent zenering the
inputs.
A few modifications to this circuit produce the ramp/pulse
VCO of Figure 16. When V
C
is varied from 1 mA to 10 nA. The output
A
x R
A
O2
. Note that the peak differential
is high, I
FIGURE 14. Voltage Controlled State Variable Filter
F
is added to I
(Continued)
C
to
15
increase amplifier A1’s bias current and thus to increase the
charging rate of capacitor C. When V
zero and the capacitor discharge current is set by I
The VC Lo-Pass Filter of Figure 11 may be used to produce
a high-quality sinusoidal VCO. The circuit of Figure 16 em-
ploys two LM13700 packages, with three of the amplifiers
configured as lo-pass filters and the fourth as a limiter/
inverter. The circuit oscillates at the frequency at which the
loop phase-shift is 360˚ or 180˚ for the inverter and 60˚ per
filter stage. This VCO operates from 5 Hz to 50 kHz with less
than 1% THD.
O2
is low, I
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F
C
goes to
.