Datasheet

FB
1
FB
2
FB
3
FB
4
9 8 67
1.6 k 1.2 k 400
500
1.5 pF
OPA836
OPA2836
www.ti.com SLOS712E –JANUARY 2011–REVISED SEPTEMBER 2013
Integrated solutions are available, but the OPA836 provides a much lower power high frequency solution. For
best CMRR performance, resistors must be matched. Assuming CMRR ≈ the resistor tolerance; so 0.1%
tolerance will provide about 60 dB CMRR.
Gain Setting with OPA836 RUN Integrated Resistors
The OPA836 RUN package option includes integrated gain setting resistors for smallest possible footprint on a
printed circuit board (≈ 2mm x 2mm). By adding circuit traces on the PCB, gains of +1, -1, -1.33, +2, +2.33, -3,
+4, -4, +5, -5.33, +6.33, -7, +8 and inverting attenuations of -0.1429, -0.1875, -0.25, -0.33, -0.75 can be
achieved.
Figure 60 shows a simplified view of how the OPA836IRUN integrated gain setting network is implemented.
Table 1 shows the required pin connections for various non-inverting and inverting gains (reference Figure 53
and Figure 54). Table 2 shows the required pin connections for various attenuations using the inverting amplifier
architecture (reference Figure 54). Due to ESD protection devices being used on all pins, the absolute maximum
and minimum input voltage range, V
S–
- 0.7V to V
S+
+ 0.7V, applies to the gain setting resistors, and so
attenuation of large input voltages will require external resistors to implement.
The gain setting resistors are laser trimmed to 1% tolerance with nominal values of 1.6 kΩ, 1.2 kΩ, and 400 Ω.
They have excellent temperature coefficient and gain tracking is superior to using external gain setting resistors.
The 500 Ω and 1.5 pF capacitor in parallel with the 1.6 kΩ gain setting resistor provide compensation for best
stability and pulse response.
Figure 60. OPA836IRUN Gain Setting Network
Table 1. Gains Setting
Non-inverting Gain Inverting Gain
Short Pins Short Pins Short Pins Short Pins
(Figure 53) (Figure 54)
1 V/V (0 dB) - 1 to 9 -
2 V/V (6.02 dB) -1 V/V (0 dB) 1 to 9 2 to 8 6 to GND -
2.33 V/V (7.36 dB) -1.33 V/V (2.5 dB) 1 to 9 2 to 8 7 to GND -
4 V/V (12.04 dB) -3 V/V (9.54 dB) 1 to 8 2 to 7 6 to GND -
5 V/V (13.98 dB) -4 V/V (12.04 dB) 1 to 9 2 to 7 or 8 7 to 8 6 to GND
6.33 V/V (16.03 dB) -5.33 V/V (14.54 dB) 1 to 9 2 to 6 or 8 6 to 8 7 to GND
8 V/V (18.06 dB) -7 V/V (16.90 dB) 1 to 9 2 to 7 6 to GND -
Table 2. Attenuator Settings
Inverting Gain
Short Pins Short Pins Short Pins Short Pins
(Figure 54)
-0.75 V/V (-2.5 dB) 1 to 7 2 to 8 9 to GND -
-0.333 V/V (-9.54 dB) 1 to 6 2 to 7 8 to GND -
-0.25 V/V (-12.04 dB) 1 to 6 2 to 7 or 8 7 to 8 9 to GND
-0.1875 V/V (-14.54 dB) 1 to 7 2 to 6 or 8 6 to 8 9 to GND
-0.1429 V/V (-16.90 dB) 1 to 6 2 to 7 9 to GND -
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