ADA4939-1YCPZ-R7 Analog Devices Inc, ADA4939-1YCPZ-R7 Datasheet - Page 23
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ADA4939-1YCPZ-R7
Manufacturer Part Number
ADA4939-1YCPZ-R7
Description
IC,Differential Amplifier,SINGLE,BIPOLAR,LLCC,16PIN,PLASTIC
Manufacturer
Analog Devices Inc
Type
Differential ADC Driverr
Datasheet
1.ADA4939-1YCPZ-R7.pdf
(24 pages)
Specifications of ADA4939-1YCPZ-R7
Amplifier Type
Differential
Number Of Circuits
1
Output Type
Differential
Slew Rate
6800 V/µs
-3db Bandwidth
1.4GHz
Current - Input Bias
10µA
Voltage - Input Offset
500µV
Current - Supply
36.5mA
Current - Output / Channel
100mA
Voltage - Supply, Single/dual (±)
3 V ~ 5.25 V, ±1.5 V ~ 2.625 V
Operating Temperature
-40°C ~ 105°C
Mounting Type
Surface Mount
Package / Case
16-LFCSP
Number Of Channels
1
Number Of Elements
1
Power Supply Requirement
Single
Common Mode Rejection Ratio
77dB
Input Resistance
0.45MOhm
Input Offset Voltage
2.8mV
Input Bias Current
2.2uA
Single Supply Voltage (typ)
5V
Dual Supply Voltage (typ)
Not RequiredV
Power Supply Rejection Ratio
80dB
Rail/rail I/o Type
No
Single Supply Voltage (min)
3V
Single Supply Voltage (max)
5.25V
Dual Supply Voltage (min)
Not RequiredV
Dual Supply Voltage (max)
Not RequiredV
Operating Temp Range
-40C to 105C
Operating Temperature Classification
Industrial
Mounting
Surface Mount
Pin Count
16
Package Type
LFCSP EP
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Gain Bandwidth Product
-
Lead Free Status / Rohs Status
Compliant
Other names
ADA4939-1YCPZ-R7TR
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
ADA4939-1YCPZ-R7
Manufacturer:
Analog Devices Inc
Quantity:
1 948
HIGH PERFORMANCE ADC DRIVING
The ADA4939 is ideally suited for broadband ac-coupled and
differential-to-differential applications on a single supply.
The circuit in Figure 54 shows a front-end connection for an
ADA4939 driving an AD9445, 14-bit, 105 MSPS ADC, with ac
coupling on the ADA4939 input and output. (The AD9445
achieves its optimum performance when driven differentially.)
The ADA4939 eliminates the need for a transformer to drive
the ADC and performs a single-ended-to-differential conversion
and buffering of the driving signal.
The ADA4939 is configured with a single 5 V supply and gain
of 2 for a single-ended input to differential output. The 60.4 Ω
termination resistor, in parallel with the single-ended input
impedance of approximately 300 Ω, provides a 50 Ω termination
for the source. The additional 27.4 Ω (227.4 Ω total) at the
inverting input balances the parallel impedance of the 50 Ω
source and the termination resistor driving the noninverting input.
SIGNAL
GENERATOR
50Ω
Figure 54. ADA4939 Driving an AD9445 ADC with AC-Coupled Input and Output
0.1µF
60.4Ω
0.1µF
200Ω
200Ω
0.1µF
27.4Ω
V
OCM
ADA4939
412Ω
+
412Ω
5V
Rev. 0 | Page 23 of 24
0.1µF
0.1µF
24.3Ω
24.3Ω
In this example, the signal generator has a 1 V p-p symmetric,
ground-referenced bipolar output when terminated in 50 Ω.
The V
and left floating such that the internal divider sets the output
common-mode voltage nominally at midsupply. Because the
inputs are ac-coupled, no dc common-mode current flows in
the feedback loops, and a nominal dc level of midsupply is
present at the amplifier input terminals. Besides placing the
amplifier inputs at their optimum levels, the ac coupling technique
lightens the load on the amplifier and dissipates less power than
applications with dc-coupled inputs. With an output common-
mode voltage of nominally 2.5 V, each ADA4937 output swings
between 2.0 V and 3.0 V, providing a gain of 2 and a 2 V p-p
differential signal to the ADC input.
The output of the amplifier is ac-coupled to the ADC through a
second-order, low-pass filter with a cutoff frequency of 100 MHz.
This reduces the noise bandwidth of the amplifier and isolates
the driver outputs from the ADC inputs.
The AD9445 is configured for a 2 V p-p full-scale input by
connecting the SENSE pin to AGND, as shown in Figure 54.
30nH
30nH
OCM
pin of the ADA4939 is bypassed for noise reduction
VIN–
47pF
VIN+
AVDD2
5V (A)
BUFFER T/H
CLOCK/
TIMING
3.3V (A)
AVDD1
AGND
ADA4939-1/ADA4939-2
3.3V (D)
DRVDD
REF
ADC
SENSE
AD9445
14