DEMO CIRCUIT 1528A LTC5582 QUICK START GUIDE LTC5582 40 MHz to 10GHz RMS Power Detector with 60dB Dynamic Range DESCRIPTION Demonstration circuit 1528A is a Mean-Squared Power Detector featuring the LTC®5582 IC. The LTC5582 is a wide dynamic range Mean Squared RF Power Detector, operational from 40MHz to 6GHz. The input dynamic range with ±1dB nonlinearity is 60dB depending on frequency(from –58dBm to +2dBm, single-ended 50Ω input). The detector output voltage slope is normally 30mV/dB, and the typical output variation over temperature is ±0.5dB at 2140MHz. The DC1528A Demo Circuit is optimized for wide frequency range of 40MHz to 5.5GHz. However, input match can be optimized above 6GHz with simple external matching. Operating above 6GHz is possible with reduced performance. Contact applications for more information. Design files for this demo board are available. Call the LTC factory. Typical Performance Summary (VCC = 3.3V, EN = 3.3V, TA = 25°C, unless otherwise noted. Test circuit shown in Figure 1.) PARAMETER CONDITION VALUE Supply Voltage 3.1V to 3.5V Supply Current 41.6mA Shutdown Current EN = Low 0.1µA EN Voltage Low, Chip Disabled HIGH, Chip Enabled 0.4V max 1V min EN Input Current VEN = 0V VEN = 3.3V 0µA 125µA Output DC Voltage No Input Signal Present 0.69V Rise Time 0.8V to 2.4V, C3 = 8nF, FRF = 100 MHz 90nS Fall Time 2.4V to 0.8V, C3 = 8nF, FRF = 100 MHz 5uS Input Frequency Range Operation over wider frequency range with reduced performance 40MHz to 10GHz RF Input Power Range CW; Single-Ended, 50Ω -56dB to 1dB Linear Dynamic Range ±1 dB linearity error 57 dB f = 2140MHz Slope 29.5mV/dB Logarithmic Intercept -85dBm Output Variation vs Temperature Normalized to Output at 25°, PIN = -47 to +0dBm ±0.5 dB Deviation from CW Response 12 dB peak-to-average ratio (4 carrier WCDMA) 0.1 dB RF Input Power Range CW; Single-Ended, 50Ω -46dB to 3dB Linear Dynamic Range ±1 dB linearity error 49dB f = 5800MHz Slope 30.9mV/dB 1 LTC5582 Logarithmic Intercept -74.7 Output Variation vs Temperature Normalized to Output at 25°C, PIN = -46 to +2dBm ±1 dB Deviation from CW Response 12dB Peak to Average Ratio(WiMAX OFDM) 0.2dB QUICK START PROCEDURE Demonstration circuit 1528A is easy to set up to evaluate the performance of the LTC5582. Care should be taken during VCC power up, to ensure the supply voltage transient does not exceed the absolute maximum. Refer to Figure 2 for measurement equipment setup and follow the procedure below: 1. Connect voltmeter’s negative (-) lead to demo board GND test point (TP2). 2. Connect voltmeter’s positive (+) lead to the demo board VOUT test point (TP6). APPLICATION NOTES: Absolute maximum ratings Supply voltage…………………………….…3.8V Enable voltage……………..…-0.3V to VCC +0.3V Input signal Power(Single-ended, 50Ω)…..18dBm Input signal Power(Differential, 50Ω)……..24dBm Operating Temperature Range….…-40°C to 85°C NOTE. For digitally modulated signals, an oscilloscope can be used to observe the AC components of the output. 3. Connect DC power supply’s negative (-) output to demo board GND test point (TP2). 4. Connect DC power supply’s positive (+) output (3.15V to 3.5V) to demo board VCC test point (TP1). 5. Connect signal generator’s output to demo board RFIN port (SMA connector J1) via coaxial cable. An optional 3dB attenuator may be inserted to improve input match, the power range will be shifted higher by 3dB. 6. Using a jumper cable, connect demo board VCC test point (TP1) to EN1 test point (TP3). Now the detector is enabled (on) and is ready for measurement. 7. Apply RF input signal at RFIN and measure the output DC voltage. 2 Figure 1. Standard demo board RF input return loss LTC5582 Figure2 Proper Equipment Measurement Set-Up Temperature compensation R5 and R6 are optional external resistors used for temperature compensation. Short them to ground will disable the compensation circuitry. R6 controls the 1st order compensation, and R5 controls the 2nd order temperature compensation. Standard demo board is optimized for the best temperature performance at 2140MHz. Frequency(MHz) R6,RT1(kΩ) R5,RT2(kΩ) 450 12 2 800 12.4 1.4 880 12 2 2000 0 2 2140 0 2 2600 0 1.6 2700 0 1.6 3000 0 1.6 3600 0 1.6 5800 0 3 7000 10 1.43 8000 10 1.43 Table 1. Suggested R5, R6 values for optimal temperature performance at various frequencies. 3 VCC RFIN GND 3.1V - 3.5V J1 TP2 1 1 C5 0.4pF 1.5 R1 3.3V 1uF C1 270pF C4 C9 100pF R4 68.1 1% 1nF C8 1nF C2 3.3V 5 4 3 2 1 GND IN- DEC IN+ VCC U1 OUT RT2 RT1 EN FLTR LTC5582IDD GND 4 11 TP1 6 7 8 9 10 3.3V C10 OPT C3 100nF R5 2k R6 0 R3 100k 1% 1 1 TP6 TP3 VOUT EN LTC5582