Datasheet LTC5508 (Analog Devices) - 7
| Manufacturer | Analog Devices |
| Description | 300MHz to 7GHz RF Power Detector with Buffered Output in SC70 Package |
| Pages / Page | 8 / 7 — APPLICATIO S I FOR ATIO. Operation. Modes of Operation. MODE. SHDN. … |
| File Format / Size | PDF / 264 Kb |
| Document Language | English |
APPLICATIO S I FOR ATIO. Operation. Modes of Operation. MODE. SHDN. OPERATION. Buffer Amplifier. Applications. RF Detector
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Text Version of Document
LTC5508
U U W U APPLICATIO S I FOR ATIO Operation
60mV. Below 60mV, the voltage gain from the peak detector to the buffer output is 4. Above 120mV, the The LTC5508 RF detector integrates several functions to voltage gain is reduced to 0.85. The compression expands provide RF power detection over frequencies ranging from the low power detector range due to higher gain. 300MHz to 7GHz. These functions include an internally compensated buffer amplifier, an RF Schottky diode peak
Modes of Operation
detector and level shift amplifier to convert the RF input signal to DC, a delay circuit to avoid voltage transients at
MODE SHDN OPERATION
VOUT when coming out of shutdown and a gain compres- Shutdown Low Disabled sion circuit to extend the detector dynamic range. Enable High Power Detect
Buffer Amplifier Applications
The buffer amplifier has a gain of two and is capable of driving a 2mA load. The buffer amplifier typically has an The LTC5508 can be used as a self-standing signal strength output voltage range of 0.25V to 1.75V. measuring receiver for a wide range of input signals from –32dBm to 12dBm for frequencies from 300MHz to 7GHz.
RF Detector
The LTC5508 can be used as a demodulator for AM and The internal RF Schottky diode peak detector and level ASK modulated signals with data rates up to 2MHz. shift amplifier converts the RF input signal to a low Depending on specific application needs, the RSSI output frequency signal. The detector demonstrates excellent can be split into two branches, providing AC-coupled data efficiency and linearity over a wide range of input power. (or audio) output and DC-coupled, RSSI output for signal The Schottky detector is biased at about 60µA and drives strength measurements and AGC. a peak detector capacitor of 28pF. The LTC5508 can be used for RF power detection and control. Refer to Application Note 91, “Low Cost Coupling
Gain Compression
Methods for RF Power Detectors Replace Directional The gain compression circuit changes the feedback ratio Couplers.” as the RF peak-detected input voltage increases above
Demo Board Schematic
VCC R3 E4 22k SHDN C1 18pF ENABLE 1 RFIN 2 SHDN RF J1 DISABLE 3 LTC5508 R1 68Ω JP1 R2 GND GND (OPT) 68Ω VCC E2 (OPT) E1 VOUT VOUT VCC VCC E3 C5 C2 C3 E5 GND (OPT) 0.1µF 100pF GND 5508 AI01 5508fa Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 7
U U W U APPLICATIO S I FOR ATIO Operation
60mV. Below 60mV, the voltage gain from the peak detector to the buffer output is 4. Above 120mV, the The LTC5508 RF detector integrates several functions to voltage gain is reduced to 0.85. The compression expands provide RF power detection over frequencies ranging from the low power detector range due to higher gain. 300MHz to 7GHz. These functions include an internally compensated buffer amplifier, an RF Schottky diode peak
Modes of Operation
detector and level shift amplifier to convert the RF input signal to DC, a delay circuit to avoid voltage transients at
MODE SHDN OPERATION
VOUT when coming out of shutdown and a gain compres- Shutdown Low Disabled sion circuit to extend the detector dynamic range. Enable High Power Detect
Buffer Amplifier Applications
The buffer amplifier has a gain of two and is capable of driving a 2mA load. The buffer amplifier typically has an The LTC5508 can be used as a self-standing signal strength output voltage range of 0.25V to 1.75V. measuring receiver for a wide range of input signals from –32dBm to 12dBm for frequencies from 300MHz to 7GHz.
RF Detector
The LTC5508 can be used as a demodulator for AM and The internal RF Schottky diode peak detector and level ASK modulated signals with data rates up to 2MHz. shift amplifier converts the RF input signal to a low Depending on specific application needs, the RSSI output frequency signal. The detector demonstrates excellent can be split into two branches, providing AC-coupled data efficiency and linearity over a wide range of input power. (or audio) output and DC-coupled, RSSI output for signal The Schottky detector is biased at about 60µA and drives strength measurements and AGC. a peak detector capacitor of 28pF. The LTC5508 can be used for RF power detection and control. Refer to Application Note 91, “Low Cost Coupling
Gain Compression
Methods for RF Power Detectors Replace Directional The gain compression circuit changes the feedback ratio Couplers.” as the RF peak-detected input voltage increases above
Demo Board Schematic
VCC R3 E4 22k SHDN C1 18pF ENABLE 1 RFIN 2 SHDN RF J1 DISABLE 3 LTC5508 R1 68Ω JP1 R2 GND GND (OPT) 68Ω VCC E2 (OPT) E1 VOUT VOUT VCC VCC E3 C5 C2 C3 E5 GND (OPT) 0.1µF 100pF GND 5508 AI01 5508fa Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 7
