Texas Instruments DIYAMP-SOT23-EVM, Руководство пользователя, Страница: 13 / 35

c _ Vout
1 4
1
2 R C
=
p ´ ´
f
c _ Vref
3 4 2
1
2 R / / R C
=
p ´ ´
f
1 4
out in ref
2 3 4
R R
V V V
R R R
æ ö æ ö
= - +
ç ÷ ç ÷
+
è ø è ø
c _ highpass
3 2
1
2 C R
=
p ´ ´
f
4
out ref
3 4
R
V V
R R
æ ö
= ç
÷
+
è ø
1 1 4
out in ref
2 2 3 4
R R R
V V 1 V
R R R R
æ ö æ ö æ ö
= - + +
ç ÷ ç ÷ ç ÷
+
è ø è ø è ø
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Schematic and PCB Layout
13 SBOU191 – July 2017
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DIYAMP-SOT23-EVM
The inverting op-amp configuration takes an input signal that is applied directly to the inverting input
terminal and outputs a signal that is the opposite polarity as the input signal. The benefit of this topology is
that it avoids common mode limitations. The load resistance for this topology is equal to R2. The values of
the resistors in the feedback network will determine the amount of gain to amplify the input signal.
The single-supply, inverting amplifier circuit provides the option to AC couple the input, filter the output,
and bias the output of the amplifier to a desired value.
Equation 9 displays the dc transfer function of the single-supply, inverting amplifier circuit configuration.
where
• C3 is shorted with a 0- Ω resistor (9)
Capacitor C3 provides the option to AC couple the input of the single-supply, inverting amplifier by
creating a high-pass filter.
Equation 10 displays the dc transfer function of the single-supply, inverting
amplifier circuit configuration.
where
• The input is AC coupled with C3 (10)
The cutoff frequency of the high-pass filter can be calculated using Equation 11 .
(11)
Equation 12 displays the transfer function when the frequency of the input signal is above the cutoff
frequency calculated in Equation 11 .
(12)
Capacitor C2 filters noise that may be introduced from the Vref input. Equation 13 calculates the cutoff
frequency due to C2.
(13)
Capacitor C4 provides the option to filter the output. The cutoff frequency of the filter can be calculated
using
Equation 14 .
(14)
The PCB layout of the top layer of the single-supply, inverting amplifier circuit configuration is displayed in
Figure 19 .
Figure 19. Single-Supply, Inverting Amplifier Top Layer