QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 748A 50MHZ TO 3GHZ RF POWER DETECTOR WITH 60dB DYNAMIC RANGE LT5534 DESCRIPTION Demonstration circuit 748A is a wide range RF power summed to generate an accurate log-linear DC volt- age proportional to the input RF signal in dB. The detector featuring the LT 5534. output is buffered with a low output impedance The LT5534 is a 50MHz to 3GHz monolithic RF power driver. The LT5534 features superior temperature detector capable of measuring RF signals over a 60dB stability and fast transient response (typical full-scale dynamic range. The RF signal in a decibel scale is setting time is 38ns). precisely converted into DC voltage on a linear scale. Design files for this circuit board are available. Call The 60dB input dynamic range is achieved using cas- the LTC factory. caded RF detectors and RF limiters. Their outputs are Table 1. Typical Performance Summary (V = 3V, EN = 3V, T = 25C, source impedance = 50WW, unless otherwise noted. Test WW A CC circuit shown in Figure 1.) PARAMETER CONDITION VALUE Supply Voltage 2.7V to 5.25V Supply Current 7mA Input Impedance 2kW Output Impedance 32W Output DC voltage No RF Input Signal 142mV f = 50MHz RF RF Input Power Range -58dBm to +2dBm Dynamic Range 3dB Linearity Error, T = -40C to 85C 60dB A Output Slope 44mV/dB Output Variation vs. Temperature P = -48dBm to -14dBm, T = -40C to 85C 0.007dB/C in A f = 900MHz RF RF Input Power Range -60dBm to 0dBm Dynamic Range 3dB Linearity Error, T = -40C to 85C 60dB A Output Slope 41mV/dB Output Variation vs. Temperature P = -48dBm to -14dBm, T = -40C to 85C 0.008dB/C in A f = 1900MHz RF RF Input Power Range -63dBm to -2dBm Dynamic Range 3dB Linearity Error, T = -40C to 85C 61dB A Output Slope 36.6mV/dB Output Variation vs. Temperature P = -48dBm to -14dBm, T = -40C to 85C 0.012dB/C in A Output intercept 50W External Termination, T = -40C to 85C -64dBm A f = 2500MHz RF RF Input Power Range -63dBm to -3dBm Dynamic Range 3dB Linearity Error, T = -40C to 85C 60dB A Output Slope 35mV/dB Output Variation vs. Temperature P = -48dBm to -14dBm, T = -40C to 85C 0.025dB/C in A 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 748A 50MHZ TO 3GHZ RF POWER DETECTOR WITH 60dB DYNAMIC RANGE QUICK START PROCEDURE Demonstration circuit 748A is easy to set up to evalu- 5. Connect RF signal generator output to demo board ate the performance of the LT5534. Refer to Figure 1 RF in port (SMA connector J1) via coaxial cable. for proper measurement equipment setup and follow 6. Using a jumper cable, connect demo board Vcc pin the procedure below: (E1) to EN pin (E4). Now the detector is enabled NOTE: Demonstration circuit 748A is optimized for (on) and is ready for measurement. evaluations over the frequency range from 50MHz to NOTE: Make sure that the power is not applied to the 2.5GHz. Its RF input port is well matched with better EN pin before it is applied to the Vcc pin. The volt- than 10dB return loss up to 2.5GHz. At higher fre- age on the EN pin must never exceed the voltage quencies, return loss can be improved with proper on the Vcc pin. matching. 7. Apply an RF input signal and measure Vout DC 1. Connect DC power supply negative (-) output to voltage. demo board Gnd pin (E3 or E5). NOTE: Do not exceed +10dBm, the absolute maxi- 2. Connect DC power supply positive (+) output (2.7V mum RF input power. to 5.25V) to demo board Vcc pin (E1). 8. The dynamic range is defined as the range over NOTE: Do not exceed 5.5V, the absolute maximum which the linearity error is within 3dB. The linear- supply voltage. ity error is calculated by the difference between the 3. Connect voltmeter negative (-) lead to demo board incremental slope of the output and the average Gnd pin (E3 or E5). output slope from -48dBm to -14dBm. 4. Connect voltmeter positive (+) lead to the demo board Vout pin (E2). Figure 1. Proper Measurement Equipment Setup 2