AN5766: Application Of The CA3020 And CA3020A Multipurpose Wide-band Power Amplifiers

[ /Title
(AN57
66)
/Subject
(Application
Of The
Ca302
0 And
Ca302
0a
Multipurpose
Wideband
Power
Amplifiers)
/Autho
r ()
/Keywords
(Intersil
Corporation,
Semiconductor,
wideband
power
amplifier,
wide
band
power
Application Of The CA3020 And CA3020A
Multipurpose Wide-band Power Amplifiers
TM
UCT
OBSOLETE PROD
ACEMENT
PL
RE
D
DE
Application
NO RECOMMEN
ILNote
ions 1-888-INTERS
at
ic
pl
Ap
l
ra
nt
Ce
Call
intersil.com
or email: centapp@
November 2000
AN5766.2
The discussions in this Note are applicable to both integrated circuit types. The CA3020A can operate in all circuits
shown for the CA3020. The CA3020, on the other hand, has
a lower voltage rating and must not be used in applications
which require voltages on the output transistors greater than
18V. The integrated circuit protects the output transistor by
limiting the drive to the output stages. The drive limited current capability of the CA3020 is less than that of the
CA3020A, but peak currents in excess of 150mA are an
assured characteristic of the CA3020.
mum supply voltage is dictated by the type of circuit operation.
For transformer loaded class B amplifier service, the maximum
supply voltages are +9V and +12V for the CA3020 and the
CA3020A, respectively. When operated as a class B amplifier,
either circuit can deliver a typical output of 150mW from a +3V
supply or 400mW from a +6V supply. At +9V, the idling dissipation can be as low as 190mW, and either circuit can deliver an
output of 550mW. An output of slightly more than 1W is available from the CA3020A when a +12V supply is used.
The CA3020 and CA3020A integrated circuits are multipurpose, multifunction power amplifiers designed for use as
power output amplifiers and driver stages in portable and
fixed communications equipment and in AC servo control
systems. The flexibility of these circuits and the high frequency capabilities of the circuit components make these
types suitable for a wide variety of applications such as
broadband amplifiers, video amplifiers, and video line drivers. Voltage gains of 60dB or more are available with a 3dB
bandwidth of 8MHz.
Circuit Description and Operation
Figure 1 shows the schematic diagram of the CA3020 and
CA3020A, and indicates the five functional block into which
the circuit can be divided for understanding of its operation.
Figure 2 shows the relationship of these blocks in block diagram form.
A key to the operation of the circuit is the voltage regulator
consisting of diodes D1, D2, and D3 and resistors R10 and
R11. The three diodes are designed to provide accurately
controlled voltages to the differential amplifier so that the
proper idling current for class B operation is established in
the output stage. The characteristics of these monolithic
diodes closely match those of the driver and output stages
so that proper bias voltages are applied over the entire military temperature range of -55oC to +125oC. The close thermal coupling of the circuit assures against thermal runaway
within the prescribed temperature and dissipation ratings of
the devices.
The discussions in this Note are applicable to both integrated circuit types. The CA3020A can operate in all circuits
shown for the CA3020. The CA3020, on the other hand, has
more limited voltage and current handling capability and
must not be used in applications which require voltage
swings on the output transistors greater than 18V or peak
currents in excess of 150mA.
The CA3020 and CA3020A are designed to operate from a
single supply voltage which may be as low as +3V. The maxiVOLTAGE REGULATOR
9
RESISTOR VALUES IN kΩ
8
11
R10 1.5
BUFFER
AMP
DIFFERENTIAL
AMPLIFIER
1.5
Q1
DRIVER
OUTPUT
STAGE
+
D1
10
1
R11
D2
0.3
R4
10
R1
1.8
R3
2.0
R6
12
D3
Q2
3
R5
10
R9
4
Q6
Q4
REG
5
Q3
Q5
R7
12
R2
0.47
12
R8
0.3
AC INPUT TO
TERMINAL NO. 10
6
BUFFER
AMP
Q7
FIGURE 1. SCHEMATIC DIAGRAM OF CA3020 AND CA3020A
INTEGRATED CIRCUIT AMPLIFIERS
1-888-INTERSIL or 321-724-7143
DRIVER
POWER
OUTPUT
AMP
ALTERNATE AC INPUT
TO TERMINAL NO. 3
7
2
1
DIFF
AMP
PUSHPULL
OUTPUT
TO
LOAD
FIGURE 2. FUNCTIONAL BLOCK DIAGRAM OF THE CA3020 AND
CA3020A
|
Intersil and Design is a trademark of Intersil Corporation.
|
Copyright © Intersil Corporation 2000
Application Note 5766
The driver stages (transistors Q4 and Q5) are emitter follower amplifiers which shift the voltage level between the collectors of the differential-amplifier transistors and the bases
of the output transistors and provide the drive current
required by the output transistors.
The power transistors (Q8 and Q7) are large, high current
devices capable of delivering peak currents greater than
0.25A. The emitters are made available to facilitate various
modes of operation or to permit the inclusion of emitter resistors for more complete stabilization of the idling current of
the amplifier. Inclusion of such resistors also reduces distortion by introducing negative feedback, but reduces the
power-output capability by limiting the available drive.
Inclusion of emitter resistors between terminals 5 and 6 and
ground also enhances the effectiveness of the internal DC
feedback supplied to the bases of transistors Q2 and Q3
through resistors R5 and R7. Any increase in the idling current in either output transistor is reflected as an increased
voltage at its base. This change is coupled to the input
through the appropriate resistor to correct for the increased
current.
A later section of this Note describes how stable class A
operation of the output stages may be obtained.
2
Operating Characteristics
Supply Voltages and Derating
The CA3020 operates with any supply voltage between +3V
and +9V. The CA3020A can also be operated with supply
voltages up to +12V with inductive loads or +25V with resistive loads. Figure 3 shows the permissible dissipation rating
of the CA3020 and CA3020A as a function of case and
ambient temperatures. At supply voltages from +6V to +12V,
a heat sink may be required for maximum power output
capability. The worst case dissipation PD MAX as a function
of power output can be calculated as follows:
PD MAX = (VCC1 ICC1 + VCC2 ICC2) + (VCC22/RCC)
where VCC1 and VCC2 are the supply voltages to the differential amplifier and output amplifier stages, respectively;
ICC1 and ICC2 are the corresponding idling currents; and
RCC is the collector-to-collector load resistance of the output
transformer. This equation is preferred to the conventional
formula for the dissipation of a class B output transistor (i.e.,
0.84 times the maximum power output) because the PD MAX
equation accounts for the device standby power and device
variability.
PERMISSIBLE DISSIPATION RATING (W)
The differential amplifier operates in a class A mode to supply the power gain and phase inversion required for the
push-pull class B driver and output stages. In normal operation, an AC signal is capacitively coupled to terminal 3, and
terminal 2 is AC grounded through a suitable capacitor.
When the signal becomes positive, transistor Q2 is turned on
and its collector voltage changes in a negative direction. The
same current flows out of the emitter of Q2 and tends to flow
to ground through resistor R2. However, the impedance of
R2 is high compared to the input impedance of the emitter of
Q8, and an alternate path is available to ground through the
emitter-to-base junction of transistor Q3 and then through
the bypass capacitor from terminal 2 to ground. Because this
path has a much lower impedance than R2, most of the current takes this alternate route. The signal current flowing into
the emitter of Q3 reduces the magnitude of that current and,
because the collector current is nearly equal to the emitter
current, the collector current in Q3 drops and the collector
voltage rises. Thus, a positive signal on terminal 3 causes a
negative AC voltage on the collector of transistor Q2 and a
positive AC voltage on transistor Q3, and provides the out-ofphase signals required to drive the succeeding stages. It
should be noted that the differential amplifier is not balanced; resistor R3 is ten percent greater than R1. This
unbalance is deliberately introduced to compensate for the
fact that all of the current in the emitter of Q2 does not flow
into Q3. Use of a larger load resistor for transistor Q3 compensates for the lower current so that the voltage swings on
the two collectors have nearly the same magnitude.
3
2
CASE TEMPERATURE
AMBIENT TEMPERATURE
1
0
25
50
75
100
125
150
175
200
225
TEMPERATURE (oC)
FIGURE 3. DISSIPATION RATING OF THE CA3020 AND
CA3020A AS A FUNCTION OF CASE AND AMBIENT TEMPERATURES
Basic Class B Amplifier
Figure 4 shows a typical audio amplifier circuit in which the
CA3020 or CA3020A can provide a power output of 0.5W or
1W, respectively. Table 1 shows performance data for both
types in this amplifier. The circuit can be used at all voltage
and power output levels applicable to the CA3020 and
CA3020A.
Application Note 5766
R11
(NOTE 2)
VCC1
VCC2
(NOTE 1)
510K
OUTPUT
LOAD
8
9
11
eIN
-
~
+
4
7
10
CA3020
CA3020A
5µF
6V
1
At low power levels, the crossover distortion of the class B
amplifier can be high if the idling current is low. For low crossover distortion, the idling current should be approximately
12mA to 24mA, depending on the efficiency, idling dissipation,
and distortion requirements of the particular application. The
idling current may be increased by connection of a jumper
between terminals 8 and 9. If higher levels of operating idling
current are desired, a resistor (R11) may be used to increase
the regulated voltage at terminal 11 by a slight amount with
additional current injection from the power supply VCC1.
12
6
5µF
3V 3
+ 5.1K
5
2
0.01
µF
+
-
5µF
3V
NOTES:
1. Better coil and transformer DF108A, Thordarson TR-192, or
equivalent.
2. See text and tables.
FIGURE 4. BASIC CLASS B AUDIO AMPLIFIER CIRCUIT
USING THE CA3020 OR CA3020A.
TABLE 1. TYPICAL PERFORMANCE OF CA3020 AND
CA3020A IN CIRCUIT OF FIGURE 4 (NOTE)
CHARACTERISTIC
CA3020
CA3020A UNITS
Power Supply
VCC1
9
9
V
VCC2
9
12
V
ICC1
15
15
mA
ICC2
24
24
mA
ICC1
16
16.6
mA
ICC2
125
140
mA
Maximum Power Output at
10% THD
550
1000
mW
Sensitivity
35
45
mV
Power Gain
75
75
dB
Input Resistance
55
55
kΩ
Efficiency
45
55
%
Signal-to-Noise Ratio
70
66
dB
% Total Harmonic Distortion at
150mW
3.1
3.3
%
Zero-Signal Idling Current
Maximum Signal Current
In some applications, it may be desirable to use the input transistor Q1 of the CA3020 or CA3020A for other purposes than
the basic buffer amplifier shown in Figure 4. In such cases, the
input AC signal can be applied directly to terminal 3.
The extended frequency range of the CA3020 and CA3020A
requires that a high-frequency AC bypass capacitor be used
at the input terminal 3. Otherwise, oscillation could occur at
the stray resonant frequencies of the external components,
particularly those of the transformers. Lead inductance may
be sufficient to cause oscillation if long power-supply leads
are not properly AC bypassed at the CA3020 or CA3020A
common ground point. Even the bypassing shown may be
insufficient unless good high-frequency construction practices are followed.
Figure 5 shows typical power output of the CA3020A at supply voltages of +3V, +6V, +9V, and +12V, and of the CA3020
at +6V and +9V, as measured in the basic class B amplifier
circuit of Figure 4. The CA3020A has higher power output for
all voltage supply conditions because of its higher peak output current capability.
TA = +25oC
Test Signal
1000Hz/600Ω Generator
Equivalent Collector-to-Collector
Load
130
Idling Current Adjust Resistor
(R11)
1000
200
1000
Ω
Ω
NOTE: Integrated circuit mounted on a beat sink, Wakefield 209 Alum. or equivalent.
3
1200
POWER OUTPUT (mW)
3K
The emitter-follower stage at the input of the amplifier in Figure 4 is used as a buffer amplifier to provide a high input
impedance. Although many variations of biasing may be
applied to this stage, the method shown is efficient and economical. The output of the buffer stage is applied to terminal
3 of the differential amplifier for proper balance of the pushpull drive to the output stages. Terminals 2 and 3 must be
bypassed for approximately 1000Ω at the desired low-frequency roll-off point.
1000
A
800
B
600
B’
400
C
C’
200
D
0
0
100
200
300
400
COLLECTOR-TO-COLLECTOR LOAD RESISTANCE (Ω)
FIGURE 5. POWER OUTPUT OF THE CA3020 AND CA3020A
AS A FUNCTION OF COLLECTOR-TO-COLLECTOR LOAD RESISTANCE RCC
Application Note 5766
small improvement in total harmonic distortion for a large
increase in idling current as the current level exceeds 15mA.
POWER SUPPLY VOLTAGE
(V)
IDLING
CURRENT (mA)
CURVE
CA3020 CA3020A
ICC1
ICC2
VCC1
VCC2
R11
(Ω)
-
A
9
10
9
12
00
B’
B
9
10
9
9
00
C’
C
7
6
6
6
00
-
D
8
8
3
3
220
TOTAL HARMONIC DISTORTION (%)
Figure 6 shows total harmonic distortion (THD) as a function
of power output for each of the voltage conditions shown in
Figure 5. The values of the collector-to-collector load resistance (RCC) and the idling-current adjust resistor (R11)
shown in the figure are given merely as a fixed reference;
they are not necessarily optimum values. Higher idling-current drain may be desired for low crossover distortion, or a
higher value of RCC may be used for better sensitivity with
less power-output capability. Because the maximum power
output occurs at the same conditions of peak-current limitations, the sensitivities at maximum power output for the
curves of Figures 5 and 6 are approximately the same.
Increasing the idling current drain by reducing the value of
the resistor R11 also improves the sensitivity.
TA = +25oC
12
C’ C
B’
B
A
10
D
8
6
4
VCC1 = 6V, VCC2 = 6V, RL = 100Ω
TOTAL HARMONIC DISTORTION
AT THE 100mW LEVEL (%)
TABLE FOR FIGURE 5 CURVES
R11 = VARIABLE, TA = +25oC
12
10
8
6
4
2
0
0
2
4
8
6
12
14
16
18
FIGURE 7. TOTAL HARMONIC DISTORTION AS A FUNCTION
OF ICC2 IDLING CURRENT FOR A SUPPLY VOLTAGE OF 6V AND AN OUTPUT OF 100mW
Applications
Audio Amplifiers
The circuit shown in Figure 4 may be used as a highly efficient class B audio power output circuit in such applications
as communications systems, AM or FM radios, tape recorders, intercoms, and linear mixers. Figure 8 shows a modification of this circuit which may be used as a transformerless
audio amplifier in any of these applications or in other portable instruments. The features of this circuit are a power output capability of 310mW for an input of 45mV, and a high
input impedance of 50,000Ω. The idling-current drain of the
circuit is 24mA. The curves of Figure 5 may be used to
determine the value of the center-tapped resistive load
required for a specified power output level (the indicated load
resistance is divided by two).
2
0
0
10
IDLING CURRENT (mA)
+9V
100
200
300
400
500
600
800
700
900 1000
POWER OUTPUT (mW)
510K
FIGURE 6. TOTAL HARMONIC DISTORTION OF THE CA3020
OR CA3020A AS A FUNCTION OF POWER OUTPUT
CA3020 CA3020A
IDLING
CURRENT
(mA)
POWER
SUPPLY
VOLTAGE (V)
9
8
10
+
RCC
(Ω)
R11
(Ω)
-
A
15
24
9
12
200
1000
B’
B
15
24
9
9
150
1000
C’
C
12
14
6
6
100
1000
-
D
9
9
3
3
50
220
Figure 7 illustrates the improvement in crossover distortion
at low power levels. Distortion at 100mW is shown as a function of idling current ICC2 (output stages only). There is a
4
1µF
- +
500K
TABLE FOR FIGURE 6 CURVES
CURVE
INPUT
5.1K
-
7
5µF
12
3
6
5
2
0.01
µF
4
CA3020
CA3020A
1
+
-
130Ω SPEAKER
OR EQUIVALENT
5µF
FIGURE 8. 310mW AUDIO AMPLIFIER WITHOUT TRANSFORMERS
Application Note 5766
The CA3020 or CA3020A provides several advantages
when used as a sound output stage or as a preamplifier
driver in communications equipment because each type is a
compact and low power drain circuit. The squelching
requirement in such applications is simple and economical.
Figure 9 shows a practical method of providing squelch to
the CA3020 or CA3020A. When the squelch switching transistor QS is in the “on” state, the CA3020 or CA3020A is “off”
and draws only fractional idling dissipation. The only current
that flows is that of the buffer-amplifier transistor Q1 in the
integrated circuit and the saturating current drain of QS. For
a circuit similar to that of Figure 8, the squelched condition
requires an idling current of approximately 7mA, as compared to a normal idling-current drain of 24mA.
Figure 10 illustrates the use of the audio amplifier shown in
Figure 4 in an intercom in which a listen/talk position switch
controls two or more remote positions. Only the speakers,
the switch, and the input transformer are added to the basic
audio amplifier circuit. A suitable power supply for the
intercom could be a 9V battery used intermittently rather
than continuously.
T1: Primary 4Ω, Secondary 25,000Ω;
Stancor A4744 or equivalent.
T2: Better coil and transformer DF1084, Thordarson TR-192, or
equivalent
Speakers: 4Ω
+9V
T2
1K
+
QS
9
510K
9
11
11
-
+
QS “ON”
7
10
4
CA3020
CA3020A
1µF
QS “OFF”
CA3020
CA3020A
0.01
µF
8
T1
5
1
500K
6
2
FIGURE 9A.
12
3
+5
- µF
5µF
+ 0.01µF
5.1K
LISTEN
IS
“ON”
REMOTE
QS COLLECTOR
LOAD LINE R10 OR
R10 + R11 OF CA3020
1
TALK
“OFF”
0
2
DIFF AMP TERMINAL 11
OPERATING VOLTAGE
ES
FIGURE 9B.
FIGURE 10. INTERCOM USING CA3020 OR CA3020A
Wide-Band Amplifiers
FIGURE 9. METHOD OF APPLYING SQUELCH TO THE CA3020
OR CA3020A TO SAVE IDLING DISSIPATION
In applications requiring high gain and impedance matching,
the CA3020 or CA3020A can be adapted for use without
complex circuit modifications. Detectors having low signal
outputs or high impedances can be easily matched to the
input of the CA3020 or CA3020A buffer amplifier. The typical
integrated circuit input impedance of 55kΩ may be too low
for crystal output devices, but the sensitivity may be sacrificed to impedance match at the input while still providing
adequate drive to the CA3020 or CA3020A. Both types may
be used in tape recorders as high-gain amplifiers, bias oscillators, or record and playback amplifiers. The availability of
two input terminals permits the use of the CA3020 or
CA3020A as a linear mixer, and thus adds to its flexibility in
systems that require adaptation to multiple functions, such
as communications equipment and tape recorders.
5
A major general-purpose application of the CA3020 and
CA3020A is to provide high gain and wide-band amplification. The CA3020 and CA3020A have typically flat gainbandwidth response to 8MHz. Although the circuits are normally biased for class B operation, only the output stages
operate in this mode. If proper DC bias conditions are
applied, the output stages may be operated as linear class A
amplifiers.
Figure 11 shows the recommended method for achieving an
economical and stable class A bias. The differential amplifier
portion of the CA3020A is placed at a potential above
ground equal to the base-emitter voltage VBE of the integrated circuit transistors (0.5V to 0.7V). In this condition, the
output stages have an emitter-current bias approximately
equal to the base-to-emitter voltage divided by the emitterto-ground resistance. The circuit in Figure 11 is a wide-band
video amplifier that provides a gain of 38dB at each of the
push-pull outputs, or 44dB in a balanced output connection.
Application Note 5766
The 3dB bandwidth of the circuit is 30Hz to 8MHz. Higher
gain-bandwidth performance can be achieved if the diode-toground voltage drop at terminal 12 is reduced. The lower
voltage drop permits the use of a higher ratio of output-stage
collector-to-emitter resistors without departure from the
desired portion of the class A load line. It is important to note
that the temperature coefficient of the terminal 12-to-ground
reference element should be sufficiently low to prevent a
large change in the current of the output stages.
+12V
77mA
150
150
INVERTED
9
10K
OUTPUT
8
11
INPUT
-
38dB GAIN
PER SIDE
BW - 8MHz
7
+
10
4
1µF
6V
CA3020
NON-INVERTED
5
1
6
2
5µF
12
3V 3
-
15
+
15
+
IN3754
4.7K
-
5µF
3V
FIGURE 11. WIDE-BAND VIDEO AMPLIFIER ILLUSTRATING
ECONOMICAL AND STABLE CLASS A BIAS OF
CA3020A
Either the CA3020 or the CA3020A may be used in this circuit
with power supplies below +18V; the CA3020A can also be
used with B+ voltages up to 25V with non-inductive loads. The
circuit of Figure 12 provides a gain of 60dB and a bandwidth
of 3.2MHz if the output transistor Q7 has a bypassed emitter
resistor. With an unbypassed output emitter resistor, the gain
is 40dB and the bandwidth is 8MHz. The output stage can
deliver a 5VRMS signal when a supply of +18V is used. For
better performance in this type of circuit, the input signal is
coupled from the buffer amplifier Q1 to the input terminal 3 of
the differential amplifier. This arrangement provides higher
gain because the collector resistor of the differential-amplifier
transistor Q3 is larger than that of Q2. (This difference results
from a requirement of differential drive balance that is not
used in this circuit.) In addition, the terminals of the unused
output transistor Q6 help to form an isolating shield between
the input at terminal 3 and the output at terminal 7. This cascade of amplifiers has a single phase inversion at the output
for much better stability than could be achieved if terminal 4
were used as the output and terminal 3 as the input.
Figure 13 illustrates the use of the CA3020 or CA3020A as a
class A linear amplifier. This circuit features a very low output
impedance and may be used as a line driver amplifier for wideband applications up to 8MHz. The circuit requires a 0.12V
peak-to-peak input for a single ended output of 1V or a balanced peak-to-peak output of 2V from a 3Ω output impedance
at each emitter. The input impedance is specified as 7800Ω,
but is primarily a function of the external 10,000Ω resistor that
provides bias to Q1 from the regulating terminal 11.
The same method for achieving class A bias is used in the
large signal swing output amplifier shown in Figure 12.
+9V
50mA
1K
IN706
5.8V
10K
3.7V
1K
+18V
30mA
10K
8
-
+
4.7K
5
4
CA3020
CA3020A
5
1.3V
6
4.7K
NON-INVERTED
2
5µF
12 2.5
OUTPUT
1.3V
3V 3
1.4 V
+ V
INVERTED
75
2.5V
+
75
IN3754
0.54V
2
5µF
12 1.6
+
3V 3
0.6 V
+ V
30
1.6V
+
IN3754
250µF
3V
5µF
3V
FIGURE 12. LARGE SIGNAL SWING OUTPUT AMPLIFIER USING CA3020 OR CA3020A
6
7
1
CA3020
CA3020A
6
11
3V
OUTPUT
4
1
8
10
1µF
6V
7
10
1µF
6V
1.95V
+
11
2.6V
INPUT
500
9.2V
9
INPUT
-
0.µF
9
5µF, 3V
FIGURE 13. CLASS A LINEAR AMPLIFIER USING CA3020 OR
CA3020A
Figure 14 illustrates the practical use of the CA3020 or
CA3020A as a tuned amplifier. This circuit uses DC biasing
similar to that shown previously, and has a gain of 70dB at a
frequency of 160kHz. The CA3020 or CA3020A can be used
as a tuned RF amplifier or oscillator at frequencies well
beyond the 8MHz bandwidth of the basic circuit.
Application Note 5766
CA3020A can drive any transformer coupled load within their
respective ratings. Several examples of typical applications
are given below.
+9V
25mA
10K
0.001µF
1mH
9
8
11
7
INPUT
10
Figure 15 illustrates the use of the CA3020 or CA3020A to
drive a germanium power output transistor to a 2.5W level.
Because the integrated circuit is required to deliver a maximum power output of less than 50mW, an unbypassed emitter
resistor can be used in the output stage to reduce distortion.
Sensitivity for an output of 2.5W is 3mV; this figure can be
improved at a slight increase in distortion by reduction of the
4.7Ω resistors between terminals 5 and 6 and ground.
OUTPUT
70dB GAIN
AT 160kHz
4
CA3020
CA3020A
0.01µF
5
1
6
2
12
Because so little of the power output capability of the
CA3020 or CA3020A is used, higher power class B stages
can easily he accommodated by selection of suitable output
transistors and appropriate transformers.
0.05µF 3
33
4.7K
IN3754
0.05µF
Figure 16 shows a medium power class B audio amplifier in
which the CA3020 or CA3020A is used as a driver. The output stage uses a pair of TO-3-type germanium output transistors which must be mounted on a heat sink for reliable
operation. Idling current for the entire system is 70mA from
the 35V supply. Sensitivity is 10mV for an output of 10W.
FIGURE 14. 160KHz TUNED AMPLIFIER USING THE CA3020 OR
CA3020A
Driver Amplifiers
The high power-pin and power-output capabilities of the
CA3020 and CA3020A make these integrated circuits highly
suitable for use as drivers for higher power stages. In most
applications, the full power output capability of the circuit is
not required, and large emitter resistors may be used in the
output stage to reduce distortion. The CA3020 and
+
50µF
12V
-
27
1.5
9
1
2N2869/2N301
7
3
12
6
0.01
µF
+
5µF
3V
T1
4
CA3020
CA3020A
T2
5
2
10
+
-
10
1.5K
270
4Ω SPEAKER
-
+
5µF
6V
4.7K
+12V
600mA
470K
1µF
6V
-
The CA3020 or CA3020A may he used as a 40Hz to 400Hz
motor controller and servo amplifier, as shown in Figure 17.
390
470K
INPUT
Motor Controller and Servo Amplifier
10
T1: primary impedance, 10,000Ω; center-tapped at 160Ω; primary direct current, 2mA; Thordarson TR-207 (entire secondary), or equivalent.
T2: primary impedance, 20Ω;primary direct current, 0.6A; secondary, 4Ωs; Thordarson TR-304, Stancor TP62, or equivalent.
FIGURE 15. 2.5W CLASS A AUDIO AMPLIFIER USING THE CA3020 OR CA3020A AS A DRIVER AMPLIFIER
7
Application Note 5766
+35V
+
50µF
12V
-
3.3K
750
1W
T1
470K
1µF
6V
1
8
9
2N2869/2N301
10
+
4
1
5µF
3V
8Ω SPEAKER
1
6
5
+
0.01
µF
12
4.7
330
2
2N2869/2N301
+
4.7K
-
3.9
7
3
-
500µF
25V
470
CA3020
CA3020A
+
-
3.9
5µF
3V
470
4.7
-
T1: primary impedance, 4,000Ω; center-tapped; secondary impedance, 600Ω; center-tapped, split; Thordarson TR-454 or equivalent.
FIGURE 16. 10W SINGLE-ENDED CLASS B AUDIO AMPLIFIER USING THE CA3020 OR CA3020A AS A DRIVER AMPLIFIER
+10VDC AT
100µF
10V
+5.6V
10
4
CA3020
CA3020A
+5V
100µF
10V
+
-
1
+1.2
V
3
0.1
µF
+0.4V
100µF
10V
20mA IDLING
5.7A FULL SIGNAL
+0.5V
2N3053
22K
1W
470
1W
+18V
IN1763A
7
+18V
2N3772
+1.7V
470
1W
6VP-P
120VRMS
0.245A, 29W
AT 40Hz-400Hz
+1.1V
0.5
10W
TO 500Ω
LOAD
12
6
+1.2V
4.7K
1W
270
1W
5
270
1W
2
+
~
+18VDC AT
8
+
0.18VP-P AT
40Hz TO 400Hz
100µF
10V
+ -
+4.7V
9
-
-
470K
17mA IDLING
52mA FULL SIGNAL
5
+4.7V
15VP-P
100µF
10V
+
-
+0.3V
22K
1W
470
1W
470
1W
0.5
10W
+1.7V
+1.1V
40VP-P
STANCOR
P-8358
2N3772
2N3053
+0.5V
FIGURE 17. MOTOR CONTROLLER AND SERVO AMPLIFIERR USING CA3020 OR CA3020A
All Intersil semiconductor products are manufactured, assembled and tested under ISO9000 quality systems certification.
Intersil semiconductor products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and
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8
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