THS4521 Datasheet, PDF (29/65 Pages) Texas Instruments – VERY LOW POWER, NEGATIVE RAIL INPUT, RAIL-TO-RAIL OUTPUT, FULLY DIFFERENTIAL AMPLIFIER

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THS4521, THS4522, THS4524
SBOS458H – DECEMBER 2008 – REVISED JUNE 2015
Feature Description (continued)
8.3.6 Typical Performance Variation With Supply Voltage
The THS4521, THS4522, and THS4524 family of devices provide excellent performance across the specified
power-supply range of 2.5 V to 5.5 V with only minor variations. The input and output voltage compliance ranges
track with the power supply in nearly a 1:1 correlation. Other changes can be observed in slew rate, output
current drive, open-loop gain, bandwidth, and distortion. Table 6 shows the typical variation to be expected in
these key performance parameters.
8.3.7 Single-Supply Operation
To facilitate testing with common lab equipment, the THS4521EVM allows for split-supply operation; most of the
characterization data presented in this data sheet is measured using split-supply power inputs. The device can
easily be used with a single-supply power input without degrading performance.
Figure 61 shows a dc-coupled single-supply circuit with single-ended inputs. This circuit can also be applied to
differential input sources.
V_IN+
R_G
R_F
PD Control
Optional;
installed to
balance
impedance seen
at V_IN+
V_S+
R_IT
PD
0.22 mF
THS452x
V_S-
V_OCM
R_G
R_F
R_IT
R_O
V_OUT-
R_O
V_OUT+
V_OCM Control
0.22 mF
Figure 61. THS4521 DC-Coupled Single-Supply With Single-Ended Inputs
The input common-mode voltage range of the THS4521, THS4522, and THS4524 family is designed to include
the negative supply voltage. in the circuit shown in Figure 61, the signal source is referenced to ground. V_OCM is
set by an external control source or, if left unconnected, the internal circuit defaults to midsupply. Together with
the input impedance of the amplifier circuit, R_IT provides input termination, which is also referenced to ground.
Note that R_IT and optional matching components are added to the alternate input to balance the impedance at
signal input.
Table 6. Typical Performance Variation Versus Power-Supply Voltage
–3-dB Small-signal bandwidth
Slew rate (2-V step)
PARAMETER
Harmonic distortion at 1 MHz, 2 V_PP, R_L = 1 kΩ
Open-loop gain (dc)
Linear output current drive
Second harmonic
Third harmonic
V_S = 5 V
145 MHz
490 V/μs
–85 dBc
–91 dBc
119 dB
55 mA
V_S = 3.3 V
135 MHz
420 V/μs
–85 dBc
–90 dBc
116 dB
35 mA
V_S = 2.5 V
125 MHz
210 V/μs
–84 dBc
–88 dBc
115 dB
24 mA
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