CN-0340: 95 dB RMS Responding RF Detector Reference Design
RF detector circuit using the ADL5902 and AD8368 to achieve a 95 dB dynamic range for power measurement in wireless base stations and QAM systems.
Overview
This reference design describes a high-dynamic-range RMS responding RF power detector. By combining the ADL5902 true RMS detector with the AD8368 variable gain amplifier (VGA), the circuit extends the typical 65 dB detection range to approximately 95 dB. A SAW filter is placed between the VGA and the detector to reduce broadband noise and maximize low-end sensitivity. The design provides linear-in-dB scaling and includes temperature compensation techniques to ensure stability across operating conditions. It is optimized for signals with varying crest factors, such as those found in LTE, WCDMA, and QAM-based systems.
Use Cases
- Wireless base stations (GSM, CDMA, WCDMA, LTE)
- QAM modulation systems
- Transmitter power measurement
- Receiver signal strength monitoring
- RMS power detection for high crest factor signals
Topics
Referenced Parts
Analog Devices
Circuit Note CN-0178 describes how the output of the ADL5902 can be interfaced to the 12-bit precision AD7466 ADC.
Analog Devices
As an alternative to the ADL5902, the ADL5906 linear-in-dB rms detector could also be used.
B5070
EPCOS
EPCOS B5070 SAW Filter Evaluation Board or Equivalent
B5070
EPCOS
• SAW filter on evaluation board (EPCOS B5070, 167
| AD8368 | Analog Devices | AD8368 800 MHz, Linear-in-dB VGA with AGC Detector |
| ADL5902- | Analog Devices | ADL5902 50 MHz to 9 GHz 65 dB TruPwr Detector |
| AD7466 | Analog Devices | Circuit Note CN-0178 describes how the output of the ADL5902 can be interfaced to the 12-bit precision AD7466 ADC. |
| ADL5906 | Analog Devices | As an alternative to the ADL5902, the ADL5906 linear-in-dB rms detector could also be used. |
| ADL5902- | Analog Devices | the ADL5902 are available from Analog Devices (ADL5902- |
| B5070 | EPCOS | EPCOS B5070 SAW Filter Evaluation Board or Equivalent |
| B5070 | EPCOS | • SAW filter on evaluation board (EPCOS B5070, 167 |