Part A
AD8138ARZ
Компания Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 4208 ПКС
- Package
- SOIC-8
- Series
- Линейные - Усилители - Специальное назначение
Replacement verdict
Compatible functional replacement candidate
The AD8138ARZ and AD8131AR are both high-speed differential amplifiers in an 8-lead SOIC package, but they are not identical drop-in substitutes. The AD8138ARZ is a fully differential ADC driver with externally settable gain and a wider supply range, while the AD8131AR is a fixed-gain (×2) differential line driver with an internal gain-setting network. Designers should confirm gain configuration, supply voltage, and output swing requirements before substituting one for the other.
Amplifier Function
Validation required
Gain Configuration
Not compatible
Supply Voltage Range
Validation required
Package Type
High match
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | AD8138ARZ | AD8131AR | Why it matters |
|---|---|---|---|
| Amplifier Type | Differential ADC Driver | Differential Line Driver | Defines the primary intended application; the AD8138 is optimized for driving ADCs while the AD8131 is optimized for cable/line driving, affecting signal integrity in each use case. |
| -3 dB Bandwidth | 320 MHz | 400 MHz | Bandwidth determines the maximum signal frequency the amplifier can pass with acceptable attenuation, critical for high-speed signal chains. |
| Slew Rate | 1150 V/µs | 2000 V/µs | Slew rate limits how fast the output can respond to large signal swings; higher slew rate supports faster large-signal transitions. |
| Input Voltage Noise | 5 nV/√Hz | 12 nV/√Hz | Lower input voltage noise improves the signal-to-noise ratio, which is especially important for high-resolution ADC driving. |
| Supply Voltage Range | ±1.4 V to ±5.5 V (2.8 V to 11 V) | ±1.5 V to ±5.5 V (3 V to 11 V) | Determines compatibility with the system power rails; slight differences affect the minimum usable supply voltage. |
| Quiescent Supply Current | ~14 mA | ~11 mA | Affects power consumption and thermal budget of the design, relevant for power-sensitive applications. |
| Output Voltage Swing | ±3.5 V (on ±5 V supply) | ±3.5 V (on ±5 V supply) | Determines the maximum signal amplitude deliverable to the load; similar swing supports comparable dynamic range. |
| Package | 8-Lead SOIC | 8-Lead SOIC | Package compatibility affects PCB footprint and drop-in substitutability; identical packages simplify replacement. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Defines the environmental range over which the device is guaranteed to meet specifications. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD8138ARZ | AD8131AR |
|---|---|---|
| Supplier | - | Analog Devices Inc.,Rochester Electronics, LLC |
| Part Status | Active | Obsolete |
| Amplifier Type | - | Differential |
| Number of Circuits | - | 1 |
| Output Type | - | Differential |
| Slew Rate | - | 2000V/µs |
| -3 dB Bandwidth | - | 400 MHz |
| Current - Input Bias | - | 500 nA |
| Voltage - Input Offset | - | 1.5 mV |
| Supply Current | - | 11.5mA |
| Current - Output / Channel | - | 60 mA |
| Voltage - Supply Span(Min) | - | 2.8 V |
| Voltage - Supply Span(Max) | - | 11 V |
| Operating Temperature | - | -40°C ~ 125°C |
| Mounting Type | Surface Mount | Surface Mount |
| Type | ADC Driver | - |
| Applications | Data Acquisition | - |
Frequently asked questions
What are the primary differences between the AD8138ARZ and the AD8131AR?
The AD8138ARZ is a differential ADC driver with external gain-setting resistors, an internal common-mode feedback loop, and a -3 dB bandwidth of 320 MHz. The AD8131AR is a fixed-gain (G = 2) differential line driver with internally set gain resistors and a -3 dB bandwidth of 400 MHz. The AD8138ARZ offers user-adjustable gain and is optimized for driving ADCs, while the AD8131AR is a fixed-gain driver intended for twisted-pair cable driving applications.
Are the AD8138ARZ and AD8131AR pin-compatible?
Both devices are offered in an 8-lead SOIC package, but they are not functionally pin-compatible. The AD8138ARZ uses external feedback and gain resistors connected to dedicated pins, whereas the AD8131AR has internal gain-setting resistors and its pin functions differ. A direct drop-in replacement is not supported without verifying pin functions and external component changes against the respective datasheets.
Can the AD8138ARZ and AD8131AR be used interchangeably in a differential signal chain?
No. The AD8138ARZ is a general-purpose differential ADC driver with externally programmable gain, while the AD8131AR is a fixed-gain (G = 2) differential line driver. Substitution requires re-evaluating gain configuration, common-mode setting, bandwidth, and output drive requirements against the manufacturer datasheets; they are not interchangeable without design validation.
What is the gain configuration of each device?
The AD8138ARZ uses external resistors to set its differential gain, allowing user-defined gain values. The AD8131AR has internally fixed gain-setting resistors providing a fixed differential gain of 2. This difference affects circuit topology and the need for external components.
How do the bandwidth specifications compare between the AD8138ARZ and AD8131AR?
Per the manufacturer datasheets, the AD8138ARZ has a -3 dB bandwidth of 320 MHz, while the AD8131AR has a -3 dB bandwidth of 400 MHz. These figures are specified under the manufacturer's test conditions and should be compared under identical operating conditions for a given design.
Which device is better suited for driving an ADC?
The AD8138ARZ is specifically characterized as a differential ADC driver with an internal common-mode feedback loop that sets the output common-mode voltage, making it suited for ADC driving. The AD8131AR is a fixed-gain differential line driver intended primarily for cable driving. Selection should be confirmed against the target ADC's input requirements and the manufacturer datasheets.
Do both devices operate from the same supply voltage range?
Both the AD8138ARZ and AD8131AR are specified for operation on ±5 V supplies (or single-supply configurations as documented by the manufacturer). Designers should verify the exact supply range and single-supply operating conditions in the respective datasheets before finalizing a design.
What package options are available for the AD8138ARZ and AD8131AR?
Both the AD8138ARZ and AD8131AR are available in an 8-lead SOIC package. The "ARZ" suffix on the AD8138ARZ denotes the RoHS-compliant SOIC package variant. Package and ordering details should be confirmed against the manufacturer's ordering guide.