BA6110 Ver la hoja de datos (PDF) - ROHM Semiconductor
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BA6110 Datasheet PDF : 7 Pages
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Standard ICs
!Attached components
(1) Positive input (Pin 1)
This is the differential positive input pin. To minimize the
distortion due to the diode bias, an input resistor is
connected in series with the signal source. By increasing
the input resistance, distortion is minimized.
However, the degree of improvement for resistances
greater than 10kΩ is about the same. An input resistance
of 1kΩ to 20kΩ is recommended.
(2) Negative input (Pin 3)
This is the differential negative input pin. It is grounded
with roughly the same resistance value as that of the
positive input pin. The offset adjustment is also
connected to this pin. Make sure a sufficiently high
resistance is used, so as not to disturb the balance of the
input resistance (see Figure 3).
(3) Input bias diode (Pin 5)
The input bias diode current (ID) is determined by this pin.
The IC input impedance when the diode is biased, if the
diode bias current is ID, is expressed as follows:
Rd =
26
ID (mA)
(Ω)
(4) Control (Pin 7)
This pin controls the differential current. By changing the
current which flows into this pin, the gain of the differential
amplifier can be changed.
(5) Output (Pin 11)
The differential amplifier gain (AV) is determined by the
resistor RO connected between the output terminal and
the Pin 7 control terminal, as follows:
Av = gm · RO =
ICONTROL (mA)
52 (mV)
× RO
Make sure the resistor is selected based on the desired
maximum output and gain.
(6) Buffer input (Pin 12)
The buffer input consists of the PNP and NPN emitter
follower. The bias current is normally about 0.8µA.
Consequently, when used within a small region of control
current, we recommend using the high input impedance
FET buffer.
(7) Buffer output resistance (Pin 14)
An 11kΩ resistor is connected between VCC and the
output within the IC. When adding an external resistance
between the GND and the output, make sure the resistor
RL = 33kΩ.
!Application example
(1) Fig.3 shows a voltage-controlled amplifier (AM
modulation) as an example of an application of the
BA6110FS.
BA6110FS
By changing the ICONTROL current on Pin 7, the differential
gain can be changed. The gain (AV), if the resistance of
Pin 11 is RO, is determined by the following equation:
Av = gm · RO =
ICONTROL (mA)
52 (mV)
× RO
Good linearity can be achieved when controlling over
three decades.
By connecting Pin 5 to the VCC by way of a resistor, the
input is biased at the diode and distortion is reduced.
The gain in this case is given by the diode impedance Rd
and the ratio of the input resistance RIN, as shown in the
following:
Av = gm · RO ×
Rd
Rd × RIN
The diode impedance Rd = (26 / ID (mA) ) Ω, so that the
Pin 5 bias current ID = (VCC - 1V) / R (Pin 5). The graph in
Fig. 6 shows the control current in relation to the open
loop gain at the diode bias. In the same way, Fig.7 shows
the control current in relation to the THD = 0.5% output at
the bias point.
Fig. 8 shows a graph of the control current in relation to
the open gain with no diode bias.
Fig. 9 shows a graph of the control current in relation to
the SN ratio.
Fig. 10 shows a graph of the diode bias current in relation
to the SN ratio.
Fig. 11 shows a graph of the power supply voltage
characteristics.
(2) Fig. 4 shows a low pass filter as an example of an
application of the BA6110FS.
The cutoff frequency fO can be changed by changing the
Pin 7 control current.
The cutoff frequency fO is expressed as:
fO =
RA · gm
(R + RA) 2πC
This is attenuated by -6dB / OCT.
Fig. 12 shows a graph of the ICONTROL in relation to the
output characteristics.
(3) Fig. 5 shows a voltage-controlled secondary low
passfilter as an example of an application of the
BA6110FS.
The cutoff frequency fO can be changed by changing
thePin 7 control current.
fO =
RA · gm
(R + RA) · 2πC
This is attenuated by - 12dB / OCT.
Fig. 13 shows a graph of the
characteristic.
ICONTROL
output
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