OPA2658 Datasheet, PDF (12/14 Pages) Burr-Brown (TI) – Dual Wideband, Low Power, Current Feedback OPERATIONAL AMPLIFIER

10
0
G = +2
–10
–20
–30
–40
–50
–60
–70
–80
–90
1M
10M
100M
1G
Frequency (MHz)
FIGURE 8. Channel-to-Channel Crosstalk.
DIFFERENTIAL GAIN AND PHASE
Differential Gain (dG) and Differential Phase (dP) are among
the more important specifications for video applications. dG
is defined as the percent change in closed-loop gain over a
specified change in output voltage level. dP is defined as the
change in degrees of the closed-loop phase over the same
output voltage change. Both dG and dP are specified at the
NTSC sub-carrier frequency of 3.58MHz and the PAL sub-
carrier of 4.43MHz. All NTSC measurements were per-
formed using a Tektronix model VM700A Video Measure-
ment Set.
dG/dP of the OPA2658 were measured with the amplifier in
a gain of +2V/V with 75Ω input impedance and the output
back-terminated in 75Ω. The input signal selected from the
generator was a 0V to 1.4V modulated ramp with sync pulse.
With these conditions the test circuit shown in Figure 9
delivered a 100IRE modulated ramp to the 75Ω input of the
video analyzer. The signal averaging feature of the analyzer
was used to establish a reference against which the perfor-
mance of the amplifier was measured. Signal averaging was
also used to measure the dg and dp of the test signal in order
to eliminate the generator’s contribution to measured ampli-
fier performance. Typical performance of the OPA2658 is
0.025% differential gain and 0.02° differential phase to both
NTSC and PAL standards.
TYPICAL APPLICATION
402Ω
402Ω
75Ω
OPA2658
75Ω
402Ω
TEK TSG 130A
402Ω
75Ω
75Ω
TEK VM700A
FIGURE 9. Configuration for Testing Differential Gain/Phase.
SPICE MODELS
Computer simulation using SPICE is often useful when
analyzing the performance of analog circuits and systems.
This is particularly true for Video and RF amplifier circuits
where parasitic capacitance and inductance can have a major
effect on circuit performance. SPICE models are available
on a disk from the Burr-Brown Applications Department.
DEMONSTRATION BOARDS
Demonstration boards are available for each OPA2658 pack-
age style. These boards implement a very low parasitic
layout that will produce the excellent frequency and pulse
responses shown in the Typical Performance Curves. For
each package style, the recommended demonstration board
is:
DEMONSTRATION BOARD
DEM-OPA265xP
DEM-OPA265xU
DEM-OPA26xxE
PACKAGE
8-Pin DIP
SO-8
MSOP-8
PRODUCT
OPA2658P
OPA2658U
OPA2658UB
OPA2658E
Contact your local Burr-Brown sales office or distributor to
order demonstration boards.
Video
Input
1/2
OPA2658
75Ω
75Ω Transmission Line
75Ω
75Ω
V_OUT
FIGURE 10. Low Distortion Video Amplifier.
®
OPA2658
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