Then these digital quantities are sent to D/A in turn for conversion and output at a certain time interval, so as long as the numbers are sent circularly, the waveform can be obtained at the bipolar output of D/A. ..
Single chip microcomputer on-chip oscillator, power-on reset and external hardware watchdog circuit are used.
There is a lot of information about waveform coding on the Internet. The following is a description of the hardware circuit design (which was found on the Internet):
Output two sine waves with equal amplitude and 90-degree phase difference as reference waveforms for object deflection measurement; The other channel outputs an angle measurement waveform, the phase of which reflects the direction of angle deviation, and the amplitude reflects the amount of angle deviation relative to the reference waveform. The special waveform generator is a device for simulating angular displacement output waveform, which is used to detect the subsequent demodulation circuit and power amplifier circuit. It takes the single chip microcomputer as the core, and after D/A conversion and amplification circuit processing, it finally outputs the reference waveform and angle measurement waveform reflecting the projectile attitude.
Software programming:
# contains "reg52.h"
# Define uchar unsigned characters
# Define uint unsigned integer
Unsigned character code table [] =; /* * * Cathode 0~9 corresponds to 16 decimal number.
//= = = = = = = = = Sine wave data = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
Uchar code sin_tab[256]=
{
0x80，0x83，0x86，0x89，0x8c，0x8f，0x92，0x95，0x98，0x9c，0x9f，0xa2，0xa5，0xa8，0xab，0xae，
0xb0，0xb3，0xb6，0xb9，0xbc，0xbf，0xc 1，0xc4，0xc7，0xc9，0xcc，0xce，0xd 1，0xd3，0xd5，0xd8，
0xda、0xdc、0xde、0xe0、0xe2、0xe4、0xe6、0xe8、0xea、0xec、0xed、0xef、0xf0、0xf2、0xf3、0xf4、
0xf6，0xf7，0xf8，0xf9，0xfa，0xfb，0xfc，0xfc，0xfd，0xfe，0xfe，0xff，0xff，0xff，0xff，0xff，0x ff，
0xff，0xff，0xff，0xff，0xff，0xff，0x ff，0xfe，0xfe，0xfd，0xfc，0xfc，0xfb，0xfa，0xf9，0xf8，0xf7，
0xf6，0xf5，0xf3，0xf2，0xf0，0xef，0xed，0xec，0xea，0xe8，0xe6，0xe4，0xe3，0xe 1，0xde，0xdc，
0xda，0xd8，0xd6，0xd3，0xd 1，0xce，0xcc，0xc9，0xc7，0xc4，0xc 1，0xbf，0xbc，0xb9，0xb6，0xb4，
0xb 1，0xae，0xab，0xa8，0xa5，0xa2，0x9f，0x9c，0x99，0x96，0x92，0x8f，0x8c，0x89，0x86，0x83，
0x80，0x7d，0x79，0x76，0x73，0x70，0x6d，0x6a，0x67，0x64，0x6 1，0x5e，0x5b，0x58，0x55，0x52，
0x4f，0x4c，0x49，0x46，0x43，0x4 1，0x3e，0x3b，0x39，0x36，0x33，0x3 1，0x2e，0x2c，0x2a，0x27，
0x25，0x23，0x2 1，0x 1f，0x 1d，0x 1b，0x 19，0x 17，0x 15，0x 14，0x 12，0x 10，0xf，0xd，0xc，0xb，
0x9，0x8，0x7，0x6，0x5，0x4，0x3，0x3，0x2，0x 1，0x 1，0x0，0x0，0x0，0x0，0x0，0x 0，
0x0，0x0，0x0，0x0，0x0，0x0，0x 1，0x 1，0x2，0x3，0x3，0x4，0x5，0x6，0x7，0x8，
0x9，0xa，0xc，0xd，0xe，0x 10，0x 12，0x 13，0x 15，0x 17，0x 18，0x 1a，0x 1c，0x 1e，0x20，0x23，
0x25，0x27，0x29，0x2c，0x2e，0x30，0x33，0x35，0x38，0x3b，0x3d，0x40，0x43，0x46，0x48，0x4b，
0x4e，0x5 1，0x54，0x57，0x5a，0x5d，0x60，0x63，0x66，0x69，0x6c，0x6f，0x73，0x76，0x79，0x7c，
};
//triangular wave signal data table
Uchar code thr_tab[32]=
{
0x00，0x0f，0x 1f，0x2f，0x3f，0x4f，0x5f，0x6f，0x7f，0x8f，0x9f，0xaf，0xbf，0xcf，0xdf，0xef，
0xff，0xef，0xdf，0xcf，0xbf，0xaf，0x9f，0x8f，0x7f，0x6f，0x5f，0x4f，0x3f，0x2f，0x 1f，0x0f
};
// -
//sawtooth signal data table
Uchar code jc_tab[33]=
{
0x00，0x08，0x0f，0x 18，0x 1f，0x28，0x2f，0x38，0x3f，0x48，0x4f，0x58，0x5f，0x68，0x6f，0x78，
0x7f，0x88，0x8f，0x98，0x9f，0xa8，0xaf，0xb8，0xbf，0xc8，0xcf，0xd8，0xdf，0xe8，0xef，0xf8，0xff
};
//Definition of digital tube position selection control port
sbit led4=p2^7；
sbit led3=p2^6；
sbit led2=p2^5；
sbit led 1=p2^4；
//key statement
sbit s 1=p2^3；
sbit s2=p2^2；
sbit s3=p2^ 1；
Unsigned character tabarry [4]; //Save the display data
char flag = 1； //Keymark, when flag= 1, it means that it has not been pressed, and when flag=0, it means that a key has been pressed.
int key count = 0； //key count
The unsigned characters waveth, wavetl// are used to add a value to the timer.
Unsigned int frecount =100; //frequency count
Unsigned int mbjs// code table count, * * * take 32 points.
//millisecond delay program
Invalid delay (integer milliseconds)
{
Ucal I;
When (ms)
{
for(I = 250； I>0; I-);
}
}
//Keyboard scanning
Void key scan ()
{
if(flag== 1)
{
If(S3==0) // Switch waveforms with S3.
{
Delems (2); //Delayed debounce
If(S3==0) // key counting, which is convenient for switching waveforms.
{
flag = 0；
key count++；
if(key count & gt； = 4)key count = 0； //Four waveforms are counted 4 times.
}
}
If(S2==0) // frequency plus 1 processing.
{
Delems (2);
If (S2==0)
{
flag = 0；
Switch (key count)
{
Case 0: // sine wave frequency plus 1
frecount++；
if(frecount & gt； 1000)frecount = 0；
Break;
Case 1: // triangular wave frequency plus 1.
frecount++；
if(frecount & gt； 1000)frecount = 0；
Break;
Case 2: // sawtooth frequency plus 1
frecount++；
if(frecount & gt； 1000)frecount = 0；
Break;
Case 3: // square wave frequency plus 1
frecount++；
if(frecount & gt； 1000)frecount = 0；
Break;
}
wave th =(65536-57603/frecount)/256； //Recalculate the initial value
wave TL =(65536-57603/frecount)% 256；
}
}
If(S 1==0) // frequency minus 1 processing.
{
Delems (2);
if(S 1==0)
{
flag = 0；
Switch (key count)
{
Case 0: // sine wave frequency minus 1.
frecount-；
if(frecount & lt； 0)frecount = 999；
Break;
Case 1: // triangle wave frequency minus 1.
frecount-；
if(frecount & lt； 0)frecount = 999；
Break;
Case 2://sawtooth frequency minus 1.
frecount-；
if(frecount & lt； 0)frecount = 999；
Break;
Case 3://square wave frequency minus 1.
frecount-；
if(frecount & lt； 0)frecount = 999；
Break;
}
wave th =(65536-57603/frecount)/256； //Recalculate the initial value
wave TL =(65536-57603/frecount)% 256；
}
}
}
If (S 1! = 0 & amp& ampS2！ = 0 & amp& ampS3！ = 0)flag = 1； //Judge whether the key pops up.
}
//data division
Invalid variation (character waveform, unsigned integer frequency)
{
ta Barry[0]= wave type； //Displays letters indicating the waveform type.
TabArry[ 1]= frequency%1000/100; //Hundreds
TabArry[2]= frequency%100/10; //Ten people
TabArry[3]= frequency%10; //bit
}
//Display function
Empty display ()
{
Switch (key count)
{
Case 0: // Shows the frequency of A and sine wave.
change(0，frecount)；
Break;
Case 1: // shows the frequency of B and triangular wave.
change(0x0b，frecount)；
Break;
Example 2: // Shows the frequency of C and sawtooth wave.
change(0x0c，frecount)；
Break;
Example 3: // Shows the frequency of d and square wave.
change(0x0d，frecount)；
Break;
}
P0 = table[tab arry[0]]； //Send the most significant code
led 1 = 0； //Open the corresponding position selection control port.
Delems (2); //Display delay
led 1 = 1； //Close the corresponding bit selection control and display the next bit.
P0 = table[tabArry[ 1]]；
led 2 = 0；
Delems (2);
led 2 = 1；
P0 = table[tabArry[2]]；
led 3 = 0；
Delems (2);
led 3 = 1；
P0 = table[tabArry[3]]；
led 4 = 0；
Delems (2);
led 4 = 1；
}
void Timerinit()
{
TMOD = 0x 0 1； //Timer0 mode 1
//Timer initial value calculation formula: X=65536-(T/T0)=65536-(f0/f/32)
TH0 = wave th =(65536-57603/frecount)/256； //The initial value of the timer is 22. 1 184MHz.
TL0 = wavetl =(65536-57603/frecount)% 256；
EA = 1； //Open host interrupt
ET0 = 1； //Open Timer 0 interrupt
TR0 = 1； //Timer 0 starts counting.
}
//main function
void main()
{
timer init()； //Timer initialization
while( 1)
{
key scan()； //Scan button
Display (); //Display program
}
}
Invalid timer 0 () interrupt 1
{
TH0 = waveth// Redistribute the initial value.
TL0 = wavetl
If (keycount==0) // Output sine wave.
{
p 1 = sin _ tab[mbjs]；
mbjs+= 8； //256 points, output a data every 8 points.
if(mbjs & gt； =256)
{
mbjs = 0；
}
}
Else if(keycount== 1) // output triangular wave.
{
p 1 = thr _ tab[mbjs]；
mbjs++；
if(mbjs & gt； =32)
{
mbjs = 0；
}
}
Else if(keycount==2) // Output sawtooth wave.
{
p 1 = JC _ tab[mbjs]；
mbjs++；
if(mbjs & gt； =32)
{
mbjs = 0；
}
}
Else if(keycount==3) // outputs a square wave.
{
mbjs++；
if(mbjs & gt； =32)
{
mbjs = 0；
}
else if(mbjs & lt； 16)p 1 = 0x ff；
else p 1 = 0x 00；
}
}
abstract
Function signal generator is a circuit that can generate various waveforms, such as triangle wave, sawtooth wave, rectangular wave (including square wave), sine wave and so on. Function signal generators are widely used in circuit experiments and equipment testing. By analyzing the principle and composition of the function waveform generator, we can design a function waveform generator which can generate triangle wave, sine wave and square wave.
In this paper, the design method of square wave-triangle wave-sine wave function generator composed of integrated operational amplifier and transistor differential amplifier is adopted. First, the comparator generates a square wave, then the integrator generates a triangular wave, and finally the differential amplifier forms a sine wave. The principle of waveform transformation is to use the nonlinearity of the transmission characteristic curve of differential amplifier.
The waveforms of square wave, triangle wave, sine wave, square wave-triangle wave conversion and triangle wave-sine wave conversion are obtained by simulation.
Key words: function signal generator, integrated operational amplifier, transistor differential amplifier.
Design purpose and significance
1 design purpose
(1) Master the principle and design method of square wave-triangle wave-sine wave function generator.
(2) Master the calculation of characteristic parameters of hysteresis comparator.
(3) Understand the working principle and application of monolithic integrated function generator 8038.
(4) Be able to use circuit simulation software for circuit debugging.
2 Design significance
As a common signal source, function generator is one of the most widely used general instruments in modern testing field.
In the development, production, testing and maintenance of various electronic components, components and complete sets of equipment, it is necessary to have a signal source, which generates voltage and current signals with different frequencies and waveforms and adds them to the device or equipment under test, and observes and measures the output response of the instrument under test together with other instruments, and analyzes and determines its performance parameters. Signal generator is the most basic and widely used electronic instrument in the field of electronic measurement. It can generate sine wave, triangle wave, square wave and other waveform signals, so it is widely used in communication, radar, navigation, aerospace and other fields.
Design content
1 Contents and requirements of course design (including original data, technical parameters, conditions, design requirements, etc.). );
1. 1 course design content
(1) The generator can automatically generate sine wave, triangle wave and square wave.
(2) A function generator is designed with integrated operational amplifier and transistor as the core.
(3) indicators:
Output waveform: sine wave, triangle wave and square wave.
Frequency range: 1Hz~ 10Hz, 10Hz~ 100Hz.
Output voltage: square wave VP-P≤24V, triangle wave VP-P=8V, sine wave VP-p >1v;
(4) The application circuit of monolithic integrated function generator 8038 is designed.
1.2 Curriculum design requirements
(1) put forward a specific plan.
(2) The schematic diagram of the design circuit is given.
(3) Circuit simulation and PCB design.
Principle of 2-function waveform generator
2. Schematic block diagram of1function waveform generator
Figure 2. Block diagram of1function generator
2.2 Overall scheme of function waveform generator
Function generator generally refers to a circuit or instrument that can automatically generate voltage waveforms such as sine wave, triangle wave, square wave, sawtooth wave and step wave. According to different uses, there are function generators that generate three or more waveforms. The devices used can be discrete devices (such as low-frequency signal function generators S 10 1 all adopt transistors) or integrated circuits (such as monolithic function generator module 8038). In order to further master the basic theory and experimental debugging technology of the circuit, this topic adopts the design method of square wave-triangular wave-sine wave function generator composed of integrated operational amplifier and transistor differential amplifier.
There are many schemes to generate sine wave, square wave and triangular wave, such as generating sine wave first, then transforming sine wave into square wave through shaping circuit, and then transforming square wave into triangular wave through integrating circuit; You can also generate a triangular wave-a square wave first, then turn the triangular wave into a sine wave, or turn the square wave into a sine wave, and so on. In this paper, the circuit design method of generating square wave-triangular wave first and then converting triangular wave into sine wave is adopted [3].
The square wave-triangle wave generating circuit consists of a comparator and an integrator. The square wave output by the comparator gets triangular wave through the integrator, and the conversion circuit from triangular wave to sine wave is mainly completed by a differential amplifier. Differential amplifier has the advantages of stable working point, high input impedance and strong anti-interference ability. Especially as a DC amplifier, it can effectively suppress zero drift, so it can convert triangular waves with very low frequency into sine waves. The principle of waveform transformation is to use the nonlinearity of transmission characteristic curve of differential amplifier.
2.3 the working principle of each component of the function waveform generator
2.3. Working principle of1square wave generating circuit
The circuit consists of a hysteresis comparator with inverting input and an RC circuit. RC loop is not only a delay link, but also a feedback network, and the output state can be automatically switched through RC charging and discharging. Let the output voltage Uo=+Uz at a certain moment, then the non-inverting input terminal potential Up=+Ut. U0 charges capacitor C forward through R3, as shown by the solid arrow in Figure 2.3. The potential n at the inverting input terminal gradually increases with the increase of time t, and when t tends to infinity, Un tends to+uz; But once Un=+Ut, slightly increased, Uo jumps from +Uz to -Uz, while Up jumps from +Ut to -Ut. Subsequently, u0 reversely charges the capacitor C through R3, as shown by the dashed arrow in the figure. Un decreases with time, and when t tends to infinity, Un tends to-uz; But once Un=-Ut, then decreases, Uo jumps from -Uz to +Uz, and Up jumps from -Ut to +Ut, and the capacitor starts to charge in the positive phase again. Repeat the above process, the circuit produces self-excited oscillation [4].
2.3.2 working principle of square wave-triangle wave conversion circuit
Figure 2.2 Square Wave-Triangle Wave Generation Circuit
The working principle is as follows:
If point A is disconnected, the whole circuit is in an open-loop state. Operational amplifiers A 1, R 1, R2 and R3, RP 1 form a voltage comparator, and C 1 is an accelerating capacitor, which can accelerate the flip of the comparator. The inverting terminal of the operational amplifier is connected to the reference voltage, that is, U-=0, and the noninverting input is connected to the input voltage Uia, R 1, which is called the balance resistance. The high level of the comparator output Uo 1 is equal to the positive supply voltage +Vcc, and the low level is equal to the negative supply voltage -Vee(|+Vcc|=|-Vee|). When U+=U-=0 of the comparator, the comparator flips, and the output Uo 1 jumps from high level to low level -Vee, or from low level Vee. Let Uo 1=+ Vcc, then
(2. 1)
After sorting out the above formula, the lower limit unit Uia_ for comparator flip is
(2.2)
If Uo 1=-Vee, the upper limit threshold potential Uia+ of comparator inversion is
(2.3)
Threshold width of comparator:
(2.4)
The voltage transfer characteristics of the comparator can be obtained from the above formula, as shown in Figure 2.3.
After point A is disconnected, operational amplifiers A2, R4, RP2, C2 and R5 form an anti-integrator, and its input signal is square wave Uo 1, so the output Uo2 of the integrator is:
(2.5)
When,
(2.6)
When,
(2.7)
It can be seen that when the input of the integrator is a square wave, the output is a triangular wave with equal rising speed and falling speed, and its waveform relationship is shown in Figure 2.4.
When point A is closed, that is, the comparator and integrator form a closed-loop circuit, the square wave-triangular wave is automatically generated. The amplitude of triangular wave is:
(2.8)
The frequency f of square wave-triangular wave is:
(2.9)
From the above two formulas (2.8) and (2.9), the following conclusions can be drawn:
(1) When adjusting the output frequency of square wave-triangle wave, potentiometer RP2 will not affect the amplitude of output waveform. If a wide range of output frequencies is needed, C2 can be used to change the frequency range, and PR2 can realize frequency fine tuning.
(2) The output amplitude of the square wave should be equal to the power supply voltage +Vcc. The output amplitude of triangular wave should not exceed the power supply voltage +Vcc.
The potentiometer RP 1 can realize fine adjustment of amplitude, but it will affect the frequency of square wave-triangular wave [3].
Figure 2.3 Voltage Transmission Characteristics of Comparator
Figure 2.4 Relationship between Square Wave and Triangular Wave Waveforms
2.3.3 Working principle of triangle wave-sine wave conversion circuit
As shown in Figure 2.5, the triangle wave-sine wave conversion circuit is mainly completed by the differential amplifier circuit.
Differential amplifier has the advantages of stable working point, high input impedance and strong anti-interference ability. Especially as a DC amplifier, it can effectively suppress zero drift, so it can convert triangular waves with very low frequency into sine waves. The principle of waveform transformation is to use the nonlinearity of differential amplifier transmission characteristic curve [1].
Figure 2.5 Triangle-sine wave conversion circuit
Analysis shows that the expression of transmission characteristic curve is:
(2. 10)
(2. 1 1)
formula
Constant current of the differential amplifier;
-When the room temperature is 25oc, the voltage equivalent of the temperature is ≈26mV.
If Uid is a triangular wave, let the expression be
(2. 12)
Where Um—— is the amplitude of triangular wave;
The period of triangular wave.
In order to make the output waveform closer to sine wave, as can be seen from Figure 2.6:
The more symmetrical the (1) transmission characteristic curve is, the narrower the linear region is.
(2) The amplitude Um of the triangular wave should just make the transistor close to the saturation region or the cutoff region.
(3) Figure 2.7 is a circuit for realizing triangle wave-sine wave transformation. Among them, RP 1 adjusts the amplitude of triangular wave, RP2 adjusts the symmetry of the circuit, and its parallel resistor RE2 is used to reduce the linear region of the differential amplifier. Capacitor C 1, C2 and C3 are d C blocking capacitors, and C4 is a filtering capacitor, which filters out harmonic components and improves the output waveform [2].
Figure 2.6 Triangle-sine wave conversion principle
Figure 2.7 Triangle-sine wave conversion circuit
2.4 Selection and calculation of circuit parameters
2.4. 1 square wave-triangular wave capacitance C 1 change (one of the key changes)
In physical connection, we couldn't get the waveform for a long time at first, and then when C2 changed from 10uf (theoretically available waveform) to 0. 1uf, the waveform was successfully obtained. In fact, some analysis shows that when C2= 10uf, the frequency is very low, which is not easy to realize in practical circuits.
2.4.2 Calculation of Triangle Wave-Sine Wave Part
The elements of comparator A 1 and integrator A2 are calculated as follows:
Derived from formula (2.8)
that is
Take, then, take, RP 1 is 47 kω. Take the balanced resistance as an example.
According to formula (2.9)
that is
, then, take, for 100 kω potentiometer. When switching frequency bands, the values of R4 and RP2 remain unchanged. Take the balanced resistance as an example.
The parameter selection principle of triangle wave-sine wave conversion circuit is that DC blocking capacitors C3, C4 and C5 should be larger, because the output frequency is very low, and the filtering capacitor depends on the output waveform. If there are many higher-order oblique wave components, it can be smaller, generally from tens of picofarads to 0. 1 microfarads. RE2= 100 ohm and RP4= 100 ohm are connected in parallel to reduce the linear range of the differential amplifier. The static operating point of the differential amplifier can be determined by observing the transmission characteristic curve and adjusting RP4 and resistor R*.
2.5 General Circuit Diagram
First, the comparator generates a square wave, then the integrator generates a triangular wave, and finally the differential amplifier forms a sine wave. As shown in figure 2.5. 1,
Fig. 2.5. Experimental circuit of1triangle wave-square wave-sine wave function generator
2.6 8038 monolithic integrated function generator
2.6. Working principle of18038
8038 consists of constant current sources I 1 and I2, voltage comparators C 1 and C2, and trigger ①. Its internal principle circuit diagram and external pin arrangement are shown in Figure 2.8 and Figure 2.9 respectively.
Fig. 2.8 schematic block diagram of 8038
Figure 2.9 8038 Pin Diagram (Top View)
1. sine wave linear adjustment; 2. Sine wave output; 3. Triangular wave output; 4. Constant current source adjustment; 5. Constant current source adjustment; 6. Positive power supply; 7. Frequency modulation bias; 8.FM control input; 9. Square wave output (open collector output); 10. External capacitance; 1 1. Negative power supply or grounding; 12. sine wave linear adjustment; 13, 14. Empty feet
In Figure 2.8, the mosfet of voltage comparators C 1 and C2 are 2VR/3 and VR/3 respectively (where VR=VCC+VEE). The sizes of current sources I 1 and I2 can be adjusted by external resistors, and I2 must be greater than I 1. When the Q-terminal output of the flip-flop is low, it controls the switch S to turn off the current source I2. The current source I 1 charges the external capacitor C, so that the voltage vC across the capacitor rises linearly with time. When vC rises to vC=2VR/3, the output of the comparator C 1 jumps, which changes the Q terminal of the flip-flop output from low level to high level, and controls the switch S to turn on the current source I2. Since I2 >: I 1, the capacitor C discharges and vC decreases linearly with time. When vC drops to vC≤VR/3, the output of comparator C2 jumps, which makes the flip-flop output Q change from high level to low level again, I2 turns off again, I 1 charges C again, and vC rises linearly with time. This cycle produces oscillation. If I2=2I 1 and the rising time of vC is equal to the falling time, a triangular wave is generated and output to Foot 3. The square wave output by the trigger is output to the foot 9 through the buffer. Sine wave converter converts triangular wave into sine wave, and then outputs it through pin 2. When i 1
In the flip-flop of Figure 2.8, when the R terminal is high and the S terminal is low, the Q terminal outputs low; Otherwise, the q terminal is high.
2.6.2 8038 constitutes a function waveform generator.
As can be seen from Figure 2.9, pin 8 is the FM voltage control input terminal, pin 7 outputs the FM bias voltage, and its value (referring to the voltage between pin 6 and pin 7) is (VCC+VEE/5), which can be used as the input voltage of pin 8. In addition, the square wave output of the device is in the form of open collector, so it is generally necessary to connect a resistor between the positive power supply and pin 9, and its value is often 10k? Approximately, as shown in Figure 2. 10. When the moving end of potentiometer Rp 1 is in the middle position and pins 8 and 7 are shorted in the figure, the outputs of pins 9, 3 and 2 are square wave, triangular wave and sine wave respectively. The oscillation frequency f of the circuit is about 0.3/[c (r1+RP1/2)]. Adjusting RP 1 and RP2 can make sine wave distortion reach an ideal level.
In Figure 2. 10, when the mobile terminal of RP 1 is in the middle position, the connection between pins 8 and 7 is broken. If a potentiometer is connected between +VCC and -VEE, and the moving terminal is connected with 8 pins, and the control voltage (i.e. frequency modulation voltage) between the positive power supply +VCC and 8 pins is changed, the oscillation frequency will change accordingly, so the circuit is a function generator with adjustable frequency. If the control voltage changes according to a certain law, a sweep function generator can be formed.
Figure 2. 10 8038 connected to the waveform generator
3 circuit simulation
3. 1 circuit simulation
3. Simulation of1.1square-triangular wave generating circuit
Figure 3. 1 square wave
Figure 3.2 Triangle wave
Figure 3.3 Square Wave-Triangle Wave
3. 1.2 Simulation of Triangle-Sine Wave Conversion Circuit
Figure 3.4 Triangle Wave-Sine Wave
refer to
Wang Yuan. Analog Electronic Technology (2nd Edition) [M]. Beijing Machinery Industry Press 2000
[2] Thanks. Experimental Test of Electronic Circuit Design (2nd Edition) [M]. Wuchang: Huazhong University of Science and Technology Press, 2000.
[3] Lu Yong. Electronic circuit experiment and simulation [M]. Tsinghua University Publishing House, 2003.
Hu. Analog electronic technology [M]. Beijing: Higher Education Press, 2000.
Zhou yueqing Basic course of analog electronic technology [M]. Tianjin university press, 200 1
Zeng jiantang Practice course of electrical and electronic engineering [M]. Beijing Machinery Industry Press 2002