Datasheet LT5534 (Analog Devices) - 8
| Manufacturer | Analog Devices |
| Description | 50MHz to 3GHz RF Power Detector with 60dB Dynamic Range |
| Pages / Page | 10 / 8 — APPLICATIONS INFORMATION. Table 2. Resistor Value for Capacitive Output. … |
| File Format / Size | PDF / 1.0 Mb |
| Document Language | English |
APPLICATIONS INFORMATION. Table 2. Resistor Value for Capacitive Output. C5 (pF). R2 (kΩ). Output Interface
Model Line for this Datasheet
Text Version of Document
LT5534
APPLICATIONS INFORMATION
downward to tailor for a particular application need. By When the output is terminated with a load capacitance simply inserting an attenuator in front of the RF input, the CL, the slew rate is then limited to 200µA/(CL + 1.5pF). power range is shifted higher by the amount of the attenu- For example, the slew rate is reduced to 17.4V/µs when ation. Moreover, due to the high RF input impedance of CL = 10pF. A capacitive load may result in output voltage the LT5534, the detecting range can be moved downward overshoot, which can be minimized with a series compen- for better detection sensitivity by using a narrow band sation resistor R2, as shown in Figure 1. The suggested L-C matching network. By this means, the sensitivity of resistor values for various capacitive loads are listed in the detector can be extended to as low as –75dBm. By Table 2. changing the value of resistor R1, the sensitivity of the detector can be fine-tuned within the range from –75dBm
Table 2. Resistor Value for Capacitive Output
to –62dBm. Though the range is adjustable, the overall
C5 (pF) R2 (kΩ)
linear dynamic range remains the same. 1.5 5 5 4
Output Interface
10 2.5 The output interface of the LT5534 is shown in Figure 4. 20 2 The output currents from the RF detectors are summed and converted into an output voltage, VOUT. The maximum The optional RC network at the output (R2 and C5 on the charging current available to the output load is about demo board) can also provide further output filtering, if 200µA. The internal compensation capacitor CC is used needed. The output bandwidth is primarily dictated by the to guarantee stable operation for a large capacitive output RC constant of this lowpass filter when its corner frequency load. The slew rate is 133V/µs, and the small-signal output is less than 30MHz. bandwidth is approximately 30MHz when the output is When a large signal (e.g., –2dBm) is present at the RF resistively terminated or open. The fastest output transient input port, the output voltage swing can be as high as response is achieved when a large signal is applied to the 2.4V. To assure proper operation of the chip, the minimum RF input port. See the Output Transient Response plot in resistive load at the output termination should be greater the Typical Performance Characteristics section. than 18kΩ. VCC + 200µA + CC VOUT – 5534 F04 OUTPUT CURRENTS FROM RF DETECTORS
Figure 4. Simplified Circuit Schematic of the Output Interface
5534fc 8 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram TEST CIRCUIT Applications Information Revision History Package Description Related Parts
APPLICATIONS INFORMATION
downward to tailor for a particular application need. By When the output is terminated with a load capacitance simply inserting an attenuator in front of the RF input, the CL, the slew rate is then limited to 200µA/(CL + 1.5pF). power range is shifted higher by the amount of the attenu- For example, the slew rate is reduced to 17.4V/µs when ation. Moreover, due to the high RF input impedance of CL = 10pF. A capacitive load may result in output voltage the LT5534, the detecting range can be moved downward overshoot, which can be minimized with a series compen- for better detection sensitivity by using a narrow band sation resistor R2, as shown in Figure 1. The suggested L-C matching network. By this means, the sensitivity of resistor values for various capacitive loads are listed in the detector can be extended to as low as –75dBm. By Table 2. changing the value of resistor R1, the sensitivity of the detector can be fine-tuned within the range from –75dBm
Table 2. Resistor Value for Capacitive Output
to –62dBm. Though the range is adjustable, the overall
C5 (pF) R2 (kΩ)
linear dynamic range remains the same. 1.5 5 5 4
Output Interface
10 2.5 The output interface of the LT5534 is shown in Figure 4. 20 2 The output currents from the RF detectors are summed and converted into an output voltage, VOUT. The maximum The optional RC network at the output (R2 and C5 on the charging current available to the output load is about demo board) can also provide further output filtering, if 200µA. The internal compensation capacitor CC is used needed. The output bandwidth is primarily dictated by the to guarantee stable operation for a large capacitive output RC constant of this lowpass filter when its corner frequency load. The slew rate is 133V/µs, and the small-signal output is less than 30MHz. bandwidth is approximately 30MHz when the output is When a large signal (e.g., –2dBm) is present at the RF resistively terminated or open. The fastest output transient input port, the output voltage swing can be as high as response is achieved when a large signal is applied to the 2.4V. To assure proper operation of the chip, the minimum RF input port. See the Output Transient Response plot in resistive load at the output termination should be greater the Typical Performance Characteristics section. than 18kΩ. VCC + 200µA + CC VOUT – 5534 F04 OUTPUT CURRENTS FROM RF DETECTORS
Figure 4. Simplified Circuit Schematic of the Output Interface
5534fc 8 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram TEST CIRCUIT Applications Information Revision History Package Description Related Parts
