RES11A10DDFR datasheet(22/56 Pages) TI2

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Voltage (V)

-0.4

-0.35

-0.3

-0.25

-0.2

-0.15

-0.1

-0.05

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

RIN1 Error

RIN2 Error

RG1 Error

RG2 Error

Figure 7-9. Resistor Actual-to-expected Mismatch

vs Divider Voltage, Absolute

Voltage (V)

-100

-80

-60

-40

-20

100

RIN1 Error

RIN2 Error

RG1 Error

RG2 Error

Figure 7-10. Resistor Actual-to-expected Mismatch

vs Divider Voltage, Normalized

This exercise is repeated for each Rx, tD1, tD2, and tM, to calculate the voltage coefficients associated with each

parameter. For example, the RES11A has a typical absolute voltage coefficient of approximately ±0.24Ω/V for

RIN and RG. When considered in ratiometric terms, the typical voltage coefficient of tD1 or tD2 is ±0.4ppm/V, and

the voltage coefficient of tM is ±0.24ppm/V.

7.3.4 Ultra-Low Noise

Noise in resistors can be evaluated in two separate regions: low-frequency flicker noise and wideband thermal

noise. Flicker, or 1/f noise, is extremely important for systems that require signal gain at frequencies less

than 100Hz. The flicker noise for thin-film resistors, including the RES11A, is lower than that of thick-film

resistor processes. Thermal noise typically dominates in the region greater than 1kHz, and increases as resistor

magnitude increases. Noise is modeled as a voltage source in series with the resistor.

For a resistive divider such as the RES11A, the thermal noise as measured at the center tap of two resistors RIN

and RG is equivalent to the thermal noise of a resistor with value RIN || RG:

eN= 4kBTR

(18)

where:

• eN is the thermal noise density in nV/√Hz

• T is the absolute temperature in kelvins (K)

• kB is the Boltzmann constant, 1.381 × 10-23J/K

• R = RIN || RG

As an example, for the RES11A40 at 25°C:

eN= 4kBTR = 4×1.38E−23JK×278K× 1kΩ∥4kΩ =3.5nV/ Hz

(19)

7.4 Device Functional Modes

The RES11A is typically used with two independently biased resistor dividers. RIN1 and RG1 in series form a

resistive divider, with RIN2 and RG2 in series forming another divider. However, the two dividers do not have to be

used independently. The resistors can be connected in series or in parallel like any other resistor.

Use one of the two GND pins to bias the part substrate. Connect the substrate to signal ground or a similar

low-impedance bias point or plane for best noise rejection. While two GND/SUB connection pins are available on

the device, connect only one of these to the ground plane. The two GND pins are internally connected through

the substrate, which is not intended to conduct significant currents. Connect only one GND pin at a time and

leave the other pin floating to prevent current return paths from developing through the substrate.

RES11A

SLPS785A – DECEMBER 2023 – REVISED OCTOBER 2025

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