Monolithic 12-Bit, 25 MSPS ADC
Low Power Dissipation: 280 mW
Single 5 V Supply
No Missing Codes Guaranteed
Differential Nonlinearity Error: ؎0.4 LSB
Complete On-Chip Sample-and-Hold Amplifier and
Signal-to-Noise and Distortion Ratio: 71 dB
Spurious-Free Dynamic Range: –85 dB
Straight Binary Output Data
Compatible with 3 V Logic
Complete 12-Bit, 25 MSPS
Monolithic A/D Converter
FUNCTIONAL BLOCK DIAGRAM
GAIN = 16
GAIN = 4
GAIN = 4
DIGITAL CORRECTION LOGIC
The AD9225 is a monolithic, single-supply, 12-bit, 25 MSPS
analog-to-digital converter with an on-chip, high performance
sample-and-hold amplifier and voltage reference. The AD9225
uses a multistage differential pipelined architecture with output
error correction logic to provide 12-bit accuracy at 25 MSPS
data rates, and guarantees no missing codes over the full operat-
ing temperature range.
The AD9225 combines a low cost, high speed CMOS process
and a novel architecture to achieve the resolution and speed of
existing bipolar implementations at a fraction of the power
consumption and cost.
The input of the AD9225 allows for easy interfacing to both
imaging and communications systems. With the device’s truly
differential input structure, the user can select a variety of input
ranges and offsets, including single-ended applications. The
dynamic performance is excellent.
The sample-and-hold amplifier (SHA) is well suited for both
multiplexed systems that switch full-scale voltage levels in succes-
sive channels and sampling single-channel inputs at frequencies
up to and well beyond the Nyquist rate.
The AD9225’s wideband input, combined with the power and
cost savings over previously available monolithics, suits applica-
tions in communications, imaging, and medical ultrasound.
The AD9225 has an on-board programmable reference. An
external reference can also be chosen to suit the dc accuracy
and temperature drift requirements of an application.
A single clock input is used to control all internal conversion
cycles. The digital output data is presented in straight binary
output format. An out-of-range signal indicates an overflow
condition that can be used with the most significant bit to deter-
mine low or high overflow.
The AD9225 is fabricated on a very cost effective CMOS pro-
cess. High speed precision analog circuits are combined with
high density logic circuits.
The AD9225 offers a complete, single-chip sampling, 12-bit,
25 MSPS analog-to-digital conversion function in 28-lead
SOIC and SSOP packages.
Low Power—The AD9225 at 280 mW consumes a fraction of
the power presently available in monolithic solutions.
On-Board Sample-and-Hold Amplifier (SHA)—The versa-
tile SHA input can be configured for either single-ended or
Out-of-Range (OTR)—The OTR output bit indicates when
the input signal is beyond the AD9225’s input range.
Single Supply—The AD9225 uses a single 5 V power supply,
simplifying system power supply design. It also features a sepa-
rate digital driven supply line to accommodate 3 V and 5 V logic
Pin Compatibility—The AD9225 is pin compatible with the
AD9220, AD9221, AD9223, and AD9224 ADCs.
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