OPA837IDBVR2 datasheet(29/64 Pages) TI2

29 / 64 page

OPA837

Signal and bias to

next stage

Signal and bias

from previous stage

5 V

2.5 V

5 V

OUT

SIG

2.5 V

OPA837, OPA2837

www.ti.com

SBOS673D – SEPTEMBER 2017 – REVISED DECEMBER 2018

Product Folder Links: OPA837 OPA2837

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Device Functional Modes (continued)

Figure 73 shows a similar inverting single-supply scenario with the reference generator replaced by the Thevenin

equivalent using resistors and the positive supply. R1 and R2 form a resistor divider from the 5-V supply and are

used to bias the positive side. To cancel the voltage offset that is otherwise caused by the input bias currents,

set the parallel value of R1 and R2 equal to the parallel value of RF and RG. C must be added to limit coupling of

noise into the positive input. For example, if gain of –2 V/V is required and RF = 2 kΩ, select RG = 1 kΩ to set the

gain. R1 = R2 = 2 × 667 Ω = 1.33 kΩ for the mid-supply voltage bias and for op-amp input-bias current

cancellation. A good value for C is 0.1 µF. The resistor divider costs less than the 2.5-V reference in Figure 72

but increases the current from the 5-V supply. Any noise or variation in the 5-V supply also comes into the circuit

through this bias setup but be band-limited by the pole formed with R1 || R2 and C.

Figure 73. Inverting Single-Supply Operation With Resistor Midsupply Biasing

These examples are only a few of the ways to implement a single-supply design. Many other designs exist that

can often be simpler if AC-coupled inputs are allowed. A good compilation of options can be found in the Single-

Supply Op Amp Design Techniques application report.

OPA837IDBVR2 Datasheet(PDF) 29 Page - Texas Instruments