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參數(shù)資料
| 型號(hào)： | LM13600M |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 運(yùn)動(dòng)控制電子 |
| 英文描述： | Dual Operational Transconductance Amplifiers with Linearizing Diodes and Buffers |
| 中文描述： | DUAL OP-AMP, 4000 uV OFFSET-MAX, 2 MHz BAND WIDTH, PDSO16 |
| 封裝： | SOP-16 |
| 文件頁數(shù)： | 7/24頁 |
| 文件大?。?/td> | 634K |
| 代理商： | LM13600M |
Linearizing Diodes
(Continued)
Notice that in deriving Equation 6 no approximations have
been made and there are no temperature-dependent terms.
The limitations are that the signal current not exceed I
/2
and that the diodes be biased with currents. In practice, re-
placing the current sources with resistors will generate insig-
nificant errors.
Controlled Impedance Buffers
The upper limit of transconductance is defined by the maxi-
mum value of I
(2 mA). The lowest value of I
for which
the amplifier will function therefore determines the overall
dynamic range.At very low values of I
, a buffer which has
very low input bias current is desirable. An FET follower sat-
isfies the low input current requirement, but is somewhat
non-linear for large voltage swing. The controlled impedance
buffer is a Darlington which modifies its input bias current to
suit the need. For low values of I
, the buffer’s input cur-
rent is minimal. At higher levels of I
, transistor Q
biases
up Q
12
with a current proportional to I
for fast slew rate.
When I
is changed, the DC level of the Darlington output
buffer will shift. In audio applications where I
is changed
suddenly, this shift may produce an audible “pop”. For these
applications the LM13700 may produce superior results.
Applications-Voltage Controlled
Amplifiers
Figure 2 shows how the linearizing diodes can be used in a
voltage-controlled amplifier. To understand the input biasing,
it is best to consider the 13 k
resistor as a current source
and use a Thevenin equivalent circuit as shown in Figure 3
This circuit is similar to Figure 1and operates the same. The
potentiometer in Figure 2 is adjusted to minimize the effects
of the control signal at the output.
For optimum signal-to-noise performance, I
should be as
large as possible as shown by the Output Voltage vs. Ampli-
fier Bias Current graph. Larger amplitudes of input signal
also improve the S/N ratio. The linearizing diodes help here
by allowing larger input signals for the same output distortion
as shown by the Distortion vs. Differential Input Voltage
graph. S/N may be optimized by adjusting the magnitude of
the input signal via R
(Figure 2) until the output distortion is
below some desired level. The output voltage swing can
then be set at any level by selecting R
L
.
Although the noise contribution of the linearizing diodes is
negligible relative to the contribution of the amplifier’s inter-
nal transistors, I
should be as large as possible. This mini-
mizes the dynamic junction resistance of the diodes (r
) and
maximizes their linearizing action when balanced against
R
. A value of 1 mA is recommended for I
D
unless the spe-
cific application demands otherwise.
DS007980-9
FIGURE 2. Voltage Controlled Amplifier
www.national.com
7
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LM13600N | Dual Operational Transconductance Amplifiers with Linearizing Diodes and Buffers |
| LM13700 | Dual Operational Transconductance Amplifiers with Linearizing Diodes and Buffers |
| LM13700AN | Dual Operational Transconductance Amplifiers with Linearizing Diodes and Buffers |
| LM13700M | Dual Operational Transconductance Amplifiers with Linearizing Diodes and Buffers |
| LM13700N | Dual Operational Transconductance Amplifiers with Linearizing Diodes and Buffers |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM13600MX | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| LM13600N | 制造商:Texas Instruments 功能描述: |
| LM13600N/B+ | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Transconductance Operational Amplifier |
| LM136-2.5 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Reference Diode |
| LM136-2.5 MD8 | 制造商:Texas Instruments 功能描述:VOLTAGE REFERENCE DIODE DIE - Gel-pak, waffle pack, wafer, diced wafer on film |
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