Part A
AD8307AR
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 2581 PCS
- Package
- SOIC-8
- Series
- Linear - Amplifiers - Special Purpose
Replacement verdict
Not a drop-in replacement
The AD8307AR and AD8306ARZ-RL7 are not drop-in replacements for one another. Although both are logarithmic amplifiers in SOIC-8 packages, they differ fundamentally in signal detection architecture, output interface, dynamic range, and operating frequency, so the AD8306ARZ-RL7 cannot be substituted for the AD8307AR without circuit redesign and full validation.
Different output interface
Different detection architecture
Different dynamic range
Different frequency range
Parts at a glance
Part B
AD8306ARZ-RL7
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 4522 PCS
- Package
- SOIC-16
- Series
- Linear - Amplifiers - Special Purpose
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | AD8307AR | AD8306ARZ-RL7 | Why it matters |
|---|---|---|---|
| Function | Logarithmic amplifier / RSSI detector | Logarithmic limiting amplifier / RSSI detector | The AD8306 includes a limiting output amplifier stage in addition to RSSI, while the AD8307 is a pure log detector; this affects whether the part can drive demodulation or limiting-signal paths. |
| Frequency Range | DC to 500 MHz | 5 MHz to 400 MHz | Operating frequency range determines whether the part can be used in a given RF front-end; the AD8307 extends to DC while the AD8306 has a defined lower frequency limit. |
| Dynamic Range | 92 dB | 100 dB | Dynamic range defines the span of input signal levels over which accurate log detection is maintained; a larger range supports wider signal-strength measurement. |
| Log Slope (Nominal) | 25 mV/dB | 20 mV/dB | The slope sets the output voltage change per dB of input; different slopes require recalibration of downstream ADC scaling and threshold detection. |
| Log Intercept | -84 dBm (at 100 MHz) | -95 dBm (at 100 MHz) | The intercept defines the reference point of the log transfer function; a different intercept shifts the absolute power calibration of the RSSI output. |
| Supply Voltage | 2.7 V to 5.5 V | 2.7 V to 6.5 V | Supply range affects compatibility with the system rail; the AD8306 tolerates a higher maximum supply voltage. |
| Supply Current | 7.5 mA (typical) | 16 mA (typical) | Quiescent current impacts power budget and thermal design; the AD8306 draws roughly twice the current of the AD8307. |
| Package | 8-Lead SOIC | 16-Lead SOIC | Package footprint and pin count determine PCB layout compatibility; the two parts are not drop-in replacements due to differing package sizes. |
| Limiting Output | Not available | Available (differential limiting output) | A limiting output enables FM demodulation and phase/frequency detection; its absence in the AD8307 restricts it to RSSI-only applications. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD8307AR | AD8306ARZ-RL7 |
|---|---|---|
| Supplier | - | Analog Devices Inc. |
| Part Status | Obsolete | Active |
| Type | Logarithmic Amplifier | Limiting-Logarithmic Amplifier |
| Applications | Receiver Signal Strength Indication (RSSI) | Receiver Signal Strength Indication (RSSI) |
| Mounting Type | Surface Mount | Surface Mount |
Frequently asked questions
What are the primary functional differences between the AD8307AR and AD8306ARZ-RL7?
The AD8307AR is a 500 MHz, 92 dB logarithmic amplifier (log amp) designed for RSSI and signal strength measurement, providing a DC output proportional to the log of the input voltage. The AD8306ARZ-RL7 is a 400 MHz, 100 dB limiting logarithmic amplifier with an on-chip RSSI and a phase-preserving limiting output, intended for applications requiring both signal strength indication and a limited output for FM demodulation or phase detection. The AD8306ARZ-RL7 includes a limiting amplifier output stage, whereas the AD8307AR provides only the logarithmic detector output.
Are the AD8307AR and AD8306ARZ-RL7 pin-compatible or package-compatible?
No. The AD8307AR is supplied in an 8-lead SOIC package, while the AD8306ARZ-RL7 is supplied in a 16-lead SOIC package. The pin counts, pin functions, and PCB land patterns differ, so they are not drop-in replacements for each other.
What are the specified operating frequency ranges for these two log amplifiers?
The AD8307AR is specified for operation from DC to 500 MHz. The AD8306ARZ-RL7 is specified for operation from DC to 400 MHz. Both are fabricated on Analog Devices' proprietary X-AMP architecture, but the AD8306ARZ-RL7's limiting output stage limits its specified upper frequency to 400 MHz.
How do the dynamic ranges of the AD8307AR and AD8306ARZ-RL7 compare?
The AD8307AR provides a nominal 92 dB dynamic range for logarithmic signal strength measurement. The AD8306ARZ-RL7 provides a nominal 100 dB dynamic range. The AD8306ARZ-RL7's wider range is achieved through its cascaded limiting amplifier stages and on-chip RSSI circuitry.
Does the AD8306ARZ-RL7 provide a limiting amplifier output that the AD8307AR lacks?
Yes. The AD8306ARZ-RL7 includes a hard-limiting output stage that provides a constant-amplitude output for input signals above a specified threshold, which is useful for FM demodulation and phase detection. The AD8307AR does not include a limiting output; it provides only a logarithmic (RSSI) voltage output proportional to input signal level.
What are the typical supply voltage and current consumption specifications for these devices?
Both devices operate from a single supply. The AD8307AR is specified for a supply voltage range of 2.7 V to 5.5 V with a typical supply current of 7.5 mA. The AD8306ARZ-RL7 is specified for a supply voltage range of 2.7 V to 5.5 V with a typical supply current of 18 mA. The higher current of the AD8306ARZ-RL7 reflects its additional limiting amplifier stages.
Can the AD8307AR be used as a direct substitute for the AD8306ARZ-RL7 in an existing design?
No. The two devices differ in package (8-lead SOIC vs. 16-lead SOIC), pin functions, dynamic range (92 dB vs. 100 dB), specified frequency range (500 MHz vs. 400 MHz), supply current (7.5 mA vs. 18 mA), and output functionality (logarithmic output only vs. logarithmic plus limiting output). A direct substitution is not possible without redesigning the PCB and validating the system requirements against the respective datasheets.
Which device is better suited for RSSI-only signal strength measurement applications?
The AD8307AR is typically the more appropriate choice for RSSI-only applications because it provides a 92 dB logarithmic output over DC to 500 MHz with lower supply current (7.5 mA typical) and a smaller 8-lead SOIC package. The AD8306ARZ-RL7 is intended for applications that also require a limiting amplifier output, such as FM demodulation or phase detection, where its additional functionality justifies the higher current consumption and larger package.