LMH6552_14 Datasheet, PDF (15/32 Pages) Texas Instruments – 1.5 GHz Fully Differential Amplifier

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LMH6552
SNOSAX9H – APRIL 2007 – REVISED MARCH 2013
R_F
R_O
R_G
V_S
a
+
V_CM
-
R_G
R_F
C_L
R_L V_O
R_O
ENABLE
Figure 44. Typical Application
When driven from a differential source, the LMH6552 provides low distortion, excellent balance, and common
mode rejection. This is true provided the resistors R_F, R_G and R_O are well matched and strict symmetry is
observed in board layout. With an intrinsic device CMRR of 80 dB, using 0.1% resistors will give a worst case
CMRR of around 60 dB for most circuits.
357:
R_S = 50:
a ^VS
58:
357:
+
V_CM
R_S = 50:
357:
58:
-
ENABLE
50:
R_L
50:
357:
Figure 45. Differential S-Parameter Test Circuit
The circuit configuration shown in Figure 45 was used to measure differential S parameters in a 50Ω
environment at a gain of 1 V/V. Refer to Figure 39 and Figure 40 in Typical Performance Characteristics V⁺ =
+5V, V^− = −5V for measurement results.
SINGLE ENDED INPUT TO DIFFERENTIAL OUTPUT OPERATION
In many applications, it is required to drive a differential input ADC from a single ended source. Traditionally,
transformers have been used to provide single to differential conversion, but these are inherently bandpass by
nature and cannot be used for DC coupled applications. The LMH6552 provides excellent performance as a
single-to-differential converter down to DC. Figure 46 shows a typical application circuit where an LMH6552 is
used to produce a differential signal from a single ended source.
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