AD8370AREZ Analog Devices Inc, AD8370AREZ Datasheet - Page 20

• Manufacturer Part Number: AD8370AREZ
• Description: IC AMP VGA DIFF LN 16TSSOP
• Manufacturer: Analog Devices Inc
• Type: Var Gain Ampr

Specifications of AD8370AREZ

• Amplifier Type: Variable Gain
• Number Of Circuits: 1
• Output Type: Differential
• Slew Rate: 5750 V/ns
• -3db Bandwidth: 750MHz
• Current - Input Bias: 400pA
• Current - Supply: 79mA
• Voltage - Supply, Single/dual (±): 3 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-TSSOP Exposed Pad, 16-eTSSOP, 16-HTSSOP
• No. Of Amplifiers: 1
• Bandwidth: 750MHz
• No. Of Channels: 1
• Supply Voltage Range: 3V To 5.5V
• Amplifier Case Style: TSSOP
• No. Of Pins: 16
• Operating Temperature Range: -40°C To +85°C
• Number Of Channels: 1
• Number Of Elements: 2
• Power Supply Requirement: Single
• Common Mode Rejection Ratio: 77dB
• Voltage Gain Db: 34dB
• Input Resistance: 0.0002@5VMohm
• Input Bias Current: 0.9@5VnA
• Single Supply Voltage (typ): 5V
• Dual Supply Voltage (typ): Not RequiredV
• Power Dissipation: 575mW
• Rail/rail I/o Type: No
• Single Supply Voltage (min): 3V
• Single Supply Voltage (max): 5.5V
• Dual Supply Voltage (min): Not RequiredV
• Dual Supply Voltage (max): Not RequiredV
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 16
• Package Type: TSSOP EP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output / Channel: -
• Gain Bandwidth Product: -
• Voltage - Input Offset: -
• Lead Free Status / Rohs Status: Compliant

AD8370
As an example, a second-order, Butterworth, low-pass filter
design is presented where the differential load impedance is
1200 Ω, and the padded source impedance of the AD8370 is
assumed to be 120 Ω. The normalized series inductor value for
the 10-to-1, load-to-source impedance ratio is 0.074 H, and the
normalized shunt capacitor is 14.814 F. For a 70 MHz cutoff
frequency, the single-ended equivalent circuit consists of a
200 nH series inductor followed by a 27 pF capacitor. To realize
the balanced equivalent, simply split the 200 nH inductor in
half to realize the network shown in Figure 56.
V
V
V
Figure 56. Second-Order, Butterworth, Low-Pass Filter Design Example
S
S
S
V
V
S
S
R
Figure 55. Single-Ended-to-Differential Network Conversion
S
R
SOURCE
R
R
S
=
2
2
S
S
= 120Ω
R
R
= 60Ω
= 60Ω
S
L
R
R
R
= 0.1
2
2
S
S
S
DE-NORMALIZED
CONFIGURATION
SINGLE-ENDED
SINGLE-ENDED
NORMALIZED
EQUIVALENT
EQUIVALENT
CONFIGURATION
L
BALANCED
SINGLE-ENDED
N
EQUIVALENT
200nH
100nH
100nH
BALANCED
= 0.074H
Z
Z
Z
2
2
S
S
S
C
N
Z
Z
P
P
14.814F
27pF
27pF
LOAD
f
f
R
R
C
C
R
R
2
2
L
L
L
L
= 1Hz
= 70MHz
= 1Ω
= 1200Ω
R
R
R
2
2
= 600Ω
= 600Ω
L
L
L
Rev. A | Page 20 of 28
A complete design example is shown in Figure 58. The AD8370
is configured for single-ended-to-differential conversion with
the input terminated down to present a single-ended 75 Ω input.
A sixth-order Chebyshev differential filter is used to interface
the output of the AD8370 to the input of the AD9430
170 MSPS, 12-bit ADC. The filter minimizes aliasing effects
and improves harmonic distortion performance.
The input of the AD9430 is terminated with a 1.5 kΩ resistor so
that the overall load presented to the filter network is ~1 kΩ.
The variable gain of the AD8370 extends the useable dynamic
range of the ADC. The measured intermodulation distortion of
the combination is presented in Figure 57 at 42 MHz.
In Figure 57, the intermodulation products are comparable to
the noise floor of the ADC. The spurious-free dynamic range of
the combination is better than 66 dB for a 70 MHz measurement
bandwidth.
3 V OPERATION
It is possible to operate the AD8370 at voltages as low as 3 V
with only minor performance degradation. Table 6 gives typical
specifications for operation at 3 V.
Table 6.
Parameter
Output IP3
P1dB
−3 dB Bandwidth
IMD3
–100
–110
–120
–130
–10
–20
–30
–40
–50
–60
–70
–80
–90
0
Figure 57. FFT Plot of Two-Tone Intermodulation Distortion at
0
10
42 MHz for the Circuit in Figure 58
20
FREQUENCY (MHz)
30
40
+23.5 dBm
Typical (70 MHz, R
+12.7 dBm
650 MHz (HG 127)
−82 dBc (R
50
L
= 1 kΩ)
60
L
= 100 Ω)
70