THS4552 Datasheet, PDF (45/71 Pages) Texas Instruments – Dual-Channel, Low-Noise, Precision, 150-MHz, Fully Differential Amplifier

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THS4552
SBOS831 – DECEMBER 2016
10.1.7 Channel-to-Channel Mismatch
Channel-to-channel dc error mismatch can be used for computing the channel-to-channel mismatch for high-
precision applications. Figure 81 shows the channel-to-channel input offset voltage mismatch histogram and
Figure 82 shows the input offset current mismatch histogram.
200
5V
180
3V
160
140
120
100
80
60
40
20
0
Input Offset Voltage mismatch (PV)
D080
Figure 81. THS4552PW Input Offset Voltage Mismatch
Histogram
180
5V
160
3V
140
120
100
80
60
40
20
0
Input Offset Current mismatch (nA)
D081
Figure 82. THS4552PW Input Offset Current Mismatch
Histogram
10.1.8 Designing Attenuators
Operating the THS4552 at a low-noise gain (or with higher feedback resistors) can cause a lower phase margin
to exist, thus giving the response peaking illustrated in Figure 1 for the gain of a 0.1 (a 1/10 attenuator) condition.
Although operating the THS4552 as an attenuator is often useful, taking a large input range to a controlled output
common-mode voltage with a purely differential signal around the V_OCM voltage, the response peaking illustrated
in Figure 1 is usually undesirable. Several approaches can be used to reduce or eliminate this peaking, usually
at the cost of higher output noise. DC attenuation at the input usually increases the output noise broadband,
whereas using an ac noise gain shaping technique that peaks the noise gain only at higher frequencies is more
desirable. This peaking output noise can then be filtered off with the typical passive RC filters often used after
this stage. Figure 83 shows a simplified schematic for the gain of 0.1-V/V test from Figure 1.
Gain of 0.1 V/V,
DC-Coupled,
Single-Ended Source to
Differential Output
THS4552 Wideband,
Fully Differential Amplifier
RF1
1k
VS+
VS-
2.5 V ⁺
-2.5 V ⁺
VIN
±
±
RG1
10 k
VOCM
VS+
±
+
FDA
±
+
PD
VS- ^VS+
VOUT
RL
1k
RG2
10 k
RF2
1k
Copyright © 2016, Texas Instruments Incorporated
Figure 83. Divide-by-10 Attenuator Application for the THS4552
Copyright © 2016, Texas Instruments Incorporated
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