AD8337-EVALZ-INV Analog Devices Inc, AD8337-EVALZ-INV Datasheet - Page 20

• Manufacturer Part Number: AD8337-EVALZ-INV
• Description: RoHS Compliant Eval Board.
• Manufacturer: Analog Devices Inc
• Series: X-AMP®r

Specifications of AD8337-EVALZ-INV

• Channels Per Ic: 1 - Single
• Amplifier Type: Voltage Feedback
• Output Type: Single-Ended
• Slew Rate: 625 V/µs
• -3db Bandwidth: 280MHz
• Operating Temperature: -40°C ~ 85°C
• Current - Supply (main Ic): 18.5mA
• Voltage - Supply, Single/dual (±): ±2.5 V ~ 5 V
• Board Type: Fully Populated
• Utilized Ic / Part: AD8337
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output / Channel: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AD8337
APPLICATIONS INFORMATION
PREAMPLIFIER CONNECTIONS
Noninverting Gain Configuration
The AD8337 preamplifier is an uncommitted current-feedback
op amp that is stable for values of R
for the noninverting feedback connections.
Two surface-mount resistors establish the preamplifier gain.
Equal values of 100 Ω configure the preamplifier for a 6 dB gain
and the device for a default gain range of 0 dB to 24 dB.
For preamplifier gains ≥2, select a value of R
R
increase the offset voltage, but smaller values compromise
stability. If R
referred noise decreases.
Inverting Gain Configuration
For applications requiring polarity inversion of negative pulses, or
for waveforms that require current sinking, the preamplifier can
be configured as an inverting gain amplifier. When configured
with bipolar supplies, the preamplifier amplifies positive or
negative input voltages with no level shifting of the common-
mode input voltage required. Figure 67 shows the AD8337
configured for inverting gain operation.
Because the AD8337 is a very high frequency device, stability
issues can occur unless the circuit board on which it is used is
carefully laid out. The stability of the preamp is affected by
parasitic capacitance around the INPN pin. To minimize stray
capacitance position the preamp gain resistors, R
close as possible to the INPN pin.
FB1
≤ 100 Ω. Higher values of R
Figure 66. AD8337 Preamplifier Configured for Noninverting Gain
Figure 67. The AD8337 Preamplifier Configured for Inverting Gain
R
FB1
G
≤ 100 Ω, the gain increases and the input-
R
FB1
R
R
FB1
R
PRAO
FB2
PRAO
INPP
INPP
INPN
FB2
INPN
3
4
5
3
4
5
FB2
PREAMPLIFIER
PREAMPLIFIER
+
–
+
–
reduce the bandwidth and
FB2
≥ 100 Ω. See Figure 66
FB2
≥ 100 Ω and
FB1
and R
FB2
, as
Rev. C | Page 20 of 32
DRIVING CAPACITIVE LOADS
Because of the large bandwidth of the AD8337, stray capacitance at
the output pin can induce peaking in the frequency response as the
gain of the amplifier begins to roll off. Figure 68 shows peaking
with two values of load capacitance using ±2.5 V supplies and
V
In the time domain, stray capacitance at the output pin can
induce overshoot on the edges of transient signals, as shown in
Figure 70 and Figure 72. The amplitude of the overshoot is also a
function of the slewing of the transient (not shown in Figure 70
and Figure 72). The transition time of the input pulses used for
Figure 70 and Figure 72 is deliberately set high at 300 ps to demon-
strate the fast response time of the amplifier. Signals with longer
transition times generate less overshoot.
GAIN
Figure 68. Peaking in the Frequency Response for Two Values of Output
Figure 69. Frequency Response for Two Values of Output Capacitance
= 0 V.
Capacitance with ±2.5 V Supplies and No Snubbing Resistor
25
20
15
10
–5
25
20
15
10
–5
100k
5
0
100k
5
0
NO SNUBBING RESISTOR
V
V
WITH 20Ω SNUBBING RESISTOR
GAIN
GAIN
C
C
C
C
C
C
L
L
L
L
L
L
= 0pF
= 10pF
= 22pF
= 0pF
= 10pF
= 22pF
= 0V
= 0V
with a 20 Ω Snubbing Resistor
1M
1M
FREQUENCY (Hz)
FREQUENCY (Hz)
10M
10M
100M
100M
500M
500M