OPA2316 Datasheet, PDF (21/46 Pages) Texas Instruments – OPAx316 10-MHz, Low-Power, Low-Noise, RRIO, 1.8-V CMOS Operational Amplifier

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OPA316, OPA2316, OPA2316S, OPA4316
SBOS703D – APRIL 2014 – REVISED DECEMBER 2014
8.2 Typical Application
Some applications require differential signals. Figure 41 shows a simple circuit to convert a single-ended input of
0.1 V to 2.4 V into a differential output of ±2.3 V on a single 2.7-V supply. The output range is intentionally limited
to maximize linearity. The circuit is composed of two amplifiers. One amplifier functions as a buffer and creates a
voltage, Vout+. The second amplifier inverts the input and adds a reference voltage to generate Vout–. Both
Vout+ and Vout– range from 0.1 V to 2.4 V. The difference, Vdiff, is the difference between Vout+ and Vout–.
This (TBD this what?) makes the differential output voltage range 2.3 V.
R₂
2.7V
-+
R₁
R₃
Vref
2.5V
R₄
2.7V
-+
+ _OPA316
Vout-
V ^Vdiff
+
Vout+
+ _OPA316
Vin
Figure 41. Schematic for a Single-Ended Input to Differential Output Conversion
8.2.1 Design Requirements
The design requirements are as follows:
• Supply voltage: 2.7 V
• Reference voltage: 2.5 V
• Input: 0.1 V to 2.4 V
• Output differential: ±2.3 V
• Output common-mode voltage: 1.25 V
• Small-signal bandwidth: 5 MHz
8.2.2 Detailed Design Procedure
The circuit in Figure 41 takes a single-ended input signal, Vin, and generates two output signals, Vout+ and
Vout– using two amplifiers and a reference voltage, Vref. Vout+ is the output of the first amplifier and is a
buffered version of the input signal, Vin (as shown in Equation 1). Vout– is the output of the second amplifier
which uses Vref to add an offset voltage to Vin and feedback to add inverting gain. The transfer function for
Vout– is given in Equation 2.
Vout Vin
(1)
Vout 
Vref
u
§
¨
©
R4
R3 R4
·
¸
¹
u
§¨©_1
R2
R1
·
¸¹

Vin
u
R2
R1
(2)
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