LT5581 6GHz RMS Power Detector with 40dB Dynamic Range FEATURES DESCRIPTION Frequency Range: 10MHz to 6GHz nn Accurate Power Measurement of High Crest Factor (Up to 12dB) Waveforms nn 40dB Log Linear Dynamic Range nn Exceptional Accuracy Over Temperature nn Fast Response Time: 1μs Rise, 8μs Fall nn Low Power: 1.4mA at 3.3V nn Log-Linear DC Output vs Input RF Power in dBm nn Small 3mm × 2mm 8-Pin DFN Package nn Single-Ended RF Input The LT®5581 is a 10MHz to 6GHz, low power monolithic precision RMS power detector. The RMS detector uses a proprietary technique to accurately measure the RF power from –34dBm to +6dBm (at 2.14GHz) of modulated signals with a crest factor as high as 12dB. It outputs a DC voltage in linear scale proportional to an RF input signal power in dBm. The LT5581 is suitable for precision power measurement and control for a wide variety of RF standards, including GSM/EDGE, CDMA, CDMA2000, W-CDMA, TD-SCDMA, UMTS, LTE and WiMAX, etc. The final DC output is connected in series with an on-chip 300Ω resistor, which enables further filtering of the output modulation ripple with just a single off-chip capacitor. nn APPLICATIONS GSM/EDGE, CMDA, CDMA2000, W-CDMA, LTE, WiMAX RF Power Control nn Pico-Cells, Femto-Cells RF Power Control nn Wireless Repeaters nn CATV/DVB Transmitters nn MIMO Wireless Access Points nn Portable RMS Power Measurement Instrumentation nn L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 7342431. TYPICAL APPLICATION 10MHz to 6GHz Infrastructure Power Amplifier Level Control DIRECTIONAL COUPLER POWER AMP VCC 2.7VDC TO 5.25VDC 0.1µF DIGITAL POWER CONTROL 1 2 ADC CFILT 0.01µF 3 4 EN LT5581 GND VOUT GND RFIN GND GND 0.01µF 8 7 50Ω LMATCH 1000pF 6 5 TA = 25°C 2 CMATCH CSQ VCC 3 RFOUT 68Ω 9 5581 TA01a LINEARITY ERROR (dB) RFIN Linearity Error vs RF Input Power, 2140MHz Modulated Waveforms 1 0 –1 –2 CW WCDMA, UL WCDMA DL 1C WCDMA DL 4C LTE DL 1C LTE DL 4C –3 –35 –30 –25 –20 –15 –10 –5 0 RF INPUT POWER (dBm) 5 10 5581 TA01b 5581fb For more information www.linear.com/LT5581 1 LT5581 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) Supply Voltage..........................................................5.5V Maximum Input Signal Power—Average..............15dBm Maximum Input Signal Power—Peak (Note 7).....25dBm DC Voltage at RFIN........................................ –0.3V to 2V VOUT Voltage.....................................–0.3V to VCC + 0.3V Maximum Junction Temperature, TJMAX................ 150°C Operating Temperature Range..................–40°C to 85°C Storage Temperature Range................... –65°C to 150°C TOP VIEW VCC 1 8 CSQ EN 2 7 RFIN 6 GND 5 GND VOUT 3 9 GND 4 DDB PACKAGE 8-LEAD (3mm × 2mm) PLASTIC DFN TJMAX = 150°C, θJA = 76°C/W EXPOSED PAD (PIN 9) IS GND, MUST BE SOLDERED TO PCB CAUTION: This part is sensitive to electrostatic discharge. It is very important that proper ESD precautions be observed when handling the LT5581. ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LT5581IDDB#PBF LT5581IDDB#TRPBF LDKM 8-Lead (3mm × 2mm) Plastic DFN –40°C to 85°C Consult LTC Marketing for parts specified with wider operating temperature ranges. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C, VCC = 3.3V, EN = 3.3V, unless otherwise noted (Note 2). Test circuit is shown in Figure 1. PARAMETER CONDITIONS MIN TYP MAX UNITS AC Input Input Frequency Range (Note 4) 10-6000 MHz Input Impedance 205||1.6 Ω||pF –34 to 6 dBm fRF = 450MHz RF Input Power Range Externally Matched to 50Ω Source Linear Dynamic Range, CW (Note 3) ±1dB Linearity Error 40 dB Linear Dynamic Range, CDMA (Note 3) ±1dB Linearity Error; CDMA 4-Carrier 40 dB Output Slope 31 mV/dB Logarithmic Intercept (Note 5) –42 dBm Output Variation vs Temperature Normalized to Output at 25˚C, –40°C < TA < 85°C; PIN = –34 to +6dBm ±1 dB Output Variation vs Temperature Normalized to Output at 25°C, –40°C < TA < 85°C; PIN = –27 to –10dBm ±0.5 dB Deviation from CW Response; PIN = –34dBm to 0dBm TETRA π/4 DQPSK CDMA 4-Carrier 64-Channel Fwd 1.23Mcps ±0.1 ±0.5 dB dB 2 5581fb For more information www.linear.com/LT5581 LT5581 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C, VCC = 3.3V, EN = 3.3V, unless otherwise noted (Note 2). Test circuit is shown in Figure 1. PARAMETER CONDITIONS MIN TYP MAX UNITS 2nd Order Harmonic Distortion At RF Input; CW Input; PIN = 0dBm –57 dBc 3rd Order Harmonic Distortion At RF Input; CW Input; PIN = 0dBm –52 dBc RF Input Power Range Externally Matched to 50Ω Source –34 to 6 dBm Linear Dynamic Range, CW (Note 3) ±1dB Linearity Error 40 dB Linear Dynamic Range, EDGE (Note 3) ±1dB Linearity Error; EDGE 3π/8-Shifted 8PSK 40 dB Output Slope 31 mV/dB Logarithmic Intercept (Note 5) –42 dBm fRF = 880MHz Output Variation vs Temperature Normalized to Output at 25°C, –40°C < TA < 85°C; PIN = –34 to +6dBm ±1 dB Output Variation vs Temperature Normalized to Output at 25°C, –40°C < TA < 85°C; PIN = –27 to –10dBm ±0.5 dB Deviation from CW Response, Pin = –34 to +6dBm EDGE 3π/8 Shifted 8PSK ±0.1 dB fRF = 2140MHz RF Input Power Range Externally Matched to 50Ω Source Linear Dynamic Range, CW (Note 3) ±1dB Linearity Error Linear Dynamic Range, WCDMA (Note 3) ±1dB Linearity Error; 4-Carrier WCDMA –34 to 6 43 dBm dB 37 dB Output Slope 31 mV/dB Logarithmic Intercept (Note 5) –42 dBm Output Variation vs Temperature Normalized to Output at 25°C, –40°C < TA < 85°C; PIN = –34 to 6dBm ±1 dB Output Variation vs Temperature Normalized to Output at 25°C, –40°C < TA < 85°C; PIN = –27 to –10dBm ±0.5 dB Maximum Deviation from CW Response PIN = –34 to –4dBm WCDMA 1-Carrier Uplink WCDMA 64-Channel 4-Carrier Downlink ± 0.1 ±0.5 dB dB fRF = 2600MHz RF Input Power Range Externally Matched to 50Ω Source Linear Dynamic Range, CW (Note 3) ±1dB Linearity Error Output Slope Logarithmic Intercept (Note 5) –34 to 6 dBm 40 dB 31 mV/dB –42 dBm Output Variation vs Temperature Normalized to Output at 25°C, –40°C < TA < 85°C; PIN = –34 to +6dBm ±1 dB Output Variation vs Temperature Normalized to Output at 25°C, –40°C < TA < 85°C; PIN = –27 to –10dBm ±0.5 dB Maximum Deviation from CW Response PIN = –34 to 2dBm WiMAX OFDMA Preamble WiMAX OFDM Burst ± 0.1 ±0.5 dB dB fRF = 3500MHz RF Input Power Range Externally Matched to 50Ω Source Linear Dynamic Range, CW (Note 3) ±1dB Linearity Error –30 to 6 dBm 36 dB Output Slope 31 mV/dB Logarithmic Intercept (Note 5) –41 dBm ±1 dB Output Variation vs Temperature Normalized to Output at 25°C, –40°C < TA < 85°C; PIN = –30 to +6dBm 5581fb For more information www.linear.com/LT5581 3 LT5581 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C, VCC = 3.3V, EN = 3.3V, unless otherwise noted (Note 2). Test circuit is shown in Figure 1. PARAMETER CONDITIONS MIN TYP MAX UNITS Output Variation vs Temperature Normalized to Output at 25°C, –40°C < TA < 85°C; PIN = –27 to –10dBm ±0.5 dB Deviation from CW Response PIN = –34 to –4dBm WiMAX OFDMA Preamble WiMAX OFDM Burst ± 0.1 ±0.5 dB dB fRF = 5800MHz RF Input Power Range Externally Matched to 50Ω Source Linear Dynamic Range, CW (Note 3) ±1dB Linearity Error –25 to 6 dBm 31 dB Output Slope 31 mV/dB Logarithmic Intercept (Note 5) –33 dBm Output Variation vs Temperature Normalized to Output at 25°C, –40°C < TA < 85°C; PIN = –25 to +6dBm ±1 dB Output Variation vs Temperature Normalized to Output at 25°C, –40°C < TA < 85°C; PIN = –20 to +6dBm ±0.5 dB Deviation from CW Response WiMAX OFDM Burst; PIN = –25 to 6dBm ±0.2 dB Output DC Voltage No Signal Applied to RF Input 180 mV Output Impedance Internal Series Resistor Allows for Off-Chip Filter Cap 300 Ω Output 5/5 mA Rise Time Output Current Sourcing/Sinking 0.2V to 1.6V, 10% to 90%, fRF = 2140MHz 1 µs Fall Time 1.6V to 0.2V, 10% to 90%, fRF = 2140MHz 8 µs Power Supply Rejection Ratio (Note 6) For Over Operating Input Power Range 49 dB Integrated Output Voltage Noise 1kHz to 6.5kHz Integration BW, PIN = 0dBm CW 150 µVRMS Enable (EN) Low = Off, High = On EN Input High Voltage (On) l EN Input Low Voltage (Off) l 2 V 0.3 V Enable Pin Input Current EN = 3.3V 20 µA Turn-On Time; CW RF input VOUT Within 10% of Final Value; PIN = 0dBm 1 µs Settling Time; RF Pulse VOUT Within 10% of Final Value; PIN = 0dBm 1 µs Power Supply Supply Voltage l 2.7 3.3 Supply Current No RF Input Signal 1.4 Shutdown Current EN = 0.3V, VCC = 3.3V 0.2 Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LT5581 is guaranteed functional over the operating temperature range from –40°C to 85°C. Note 3: The linearity error is calculated by the difference between the incremental slope of the output and the average output slope from –20dBm to 0dBm. The dynamic range is defined as the range over which the linearity error is within ± 1dB. 4 5.25 V mA 6 µA Note 4: An external capacitor at the CSQ pin should be used for input frequencies below 250MHz. Lower frequency operation results in excessive RF ripple in the output voltage. Note 5: Logarithmic intercept is an extrapolated input power level from the best fitted log-linear straight line, where the output voltage is 0V. Note 6: PSRR is determined as the dB value of the change in VOUT voltage over the change in VCC supply voltage. Note 7: Not production tested. Guaranteed by design and correlation to production tested parameters. 5581fb For more information www.linear.com/LT5581 LT5581 TYPICAL PERFORMANCE CHARACTERISTICS EN = 3.3V and TA = 25°C, unless otherwise noted. (Test circuit shown in Figure 1) 1.2 1.0 10MHz 450MHz 880MHz 2.14GHz 2.6GHz 3.5GHz 5.8GHz 1.6 1.4 0.8 1.2 0.6 0.4 0.2 0.2 5 5581 G01 2.5 25°C 85°C – 40°C 1.5 1.4 1.0 1.2 0.5 1.0 0 0.8 –0.5 0.6 –1.0 0.4 –1.5 0.2 –2.0 0 –40 –35 –30 –25 –20 –15 –10 –5 0 RF INPUT POWER (dBm) 5 2 2 10 0 85°C –40°C –1 –3 –40 –35 –30 –25 –20 –15 –10 –5 0 RF INPUT POWER (dBm) 5 1.0 1.2 0.5 1.0 0 0.8 –0.5 0.6 –1.0 0.4 –1.5 0.2 –2.0 5 10 5581 G07 –2.5 VARIATION (dB) 1.5 1.4 0 –40 –35 –30 –25 –20 –15 –10 –5 0 RF INPUT POWER (dBm) 0 –1 –3 –35 –30 –25 –20 –15 –10 –5 0 RF INPUT POWER (dBm) 10 3 2 2 0 10 Linearity Error vs RF Input Power, 880MHz Modulated Waveforms 3 1 5 5581 G06 2.0 LINEARITY ERROR (dB) VOUT (V) 1.6 1 Linearity Error Temperature Variation from 25°C at 880MHz 2.5 25°C 85°C – 40°C CW TETRA CDMA 4C 5581 G05 Output Voltage and Linearity Error at 880MHz 1.8 TA = 25°C –2 –2 –2.5 10 Linearity Error vs RF Input Power, 450MHz Modulated Waveforms 3 1 5 5581 G03 3 5581 G04 2.0 10MHz 450MHz 880MHz 2.14GHz 2.6GHz 3.5GHz 5.8GHz –3 –40 –35 –30 –25 –20 –15 –10 –5 0 RF INPUT POWER (dBm) 10 2.0 LINEARITY ERROR (dB) VOUT (V) 1.6 –1 Linearity Error Temperature Variation from 25°C at 450MHz VARIATION (dB) 1.8 0 5581 G02 Output Voltage and Linearity Error at 450MHz 2.0 1 –2 0 –40 –35 –30 –25 –20 –15 –10 –5 0 RF INPUT POWER (dBm) 10 TA = 25°C 2 0.8 0.4 5 880MHz 2.14GHz 2.6GHz 3.5GHz 1.0 0.6 0 –40 –35 –30 –25 –20 –15 –10 –5 0 RF INPUT POWER (dBm) TA = 25°C LINEARITY ERROR(dB) VOUT (V) 1.4 1.8 Linearity Error vs Frequency 3 LINEARITY ERROR(dB) 1.6 TA = 25°C VOUT (V) 1.8 Output Voltage vs Frequency 2.0 LINEARITY ERROR (dB) Output Voltage vs Frequency 2.0 Performance characteristics taken at VCC = 3.3V, 85°C –40°C –1 TA = 25°C CW EDGE 1 0 –1 –2 –2 –3 –40 –35 –30 –25 –20 –15 –10 –5 0 RF INPUT POWER (dBm) 5 10 5581 G08 –3 –35 –30 –25 –20 –15 –10 –5 0 RF INPUT POWER (dBm) 5 10 5581 G09 5581fb For more information www.linear.com/LT5581 5 LT5581 TYPICAL PERFORMANCE CHARACTERISTICS Output Voltage and Linearity Error at 2140MHz 3 2 2 1.0 1.2 0.5 1.0 0 0.8 –0.5 0.6 –1.0 0.4 –1.5 0.2 –2.0 5 10 1 0 –2.5 0.5 1.0 0 0.8 –0.5 3 2 2 0.6 –1.0 0.4 –1.5 0.2 –2.0 10 0 85°C –40°C –1 –2 –2.5 5581 G13 1.0 1.2 0.5 1.0 0 0.8 –0.5 0.6 –1.0 0.4 –1.5 0.2 –2.0 5 10 5581 G16 6 –2.5 VARIATION (dB) 1.5 1.4 0 –40 –35 –30 –25 –20 –15 –10 –5 0 RF INPUT POWER (dBm) CW WiMax OFDM PREAMBLE WiMax OFDM BURST WiMax OFDMA PREAMBLE –3 –35 –30 –25 –20 –15 –10 –5 0 RF INPUT POWER (dBm) 10 3 2 2 0 85°C –40°C –1 5 10 5581 G17 TA = 25°C 1 0 –1 –2 –2 –3 –40 –35 –30 –25 –20 –15 –10 –5 0 RF INPUT POWER (dBm) 10 Linearity Error vs RF Input Power, 3.5GHz Modulated Waveforms 3 1 5 5581 G15 2.0 LINEARITY ERROR (dB) VOUT (V) 1.6 –1 Linearity Error Temperature Variation from 25°C at 3500MHz 2.5 25°C 85°C – 40°C 0 5581 G14 Output Voltage and Linearity Error at 3500MHz 1.8 5 TA = 25°C 1 –2 –3 –40 –35 –30 –25 –20 –15 –10 –5 0 RF INPUT POWER (dBm) 10 Linearity Error vs RF Input Power, 2.6GHz Modulated Waveforms 3 1 5 5581 G12 LINEARITY ERROR (dB) 1.2 VARIATION (dB) 1.5 5 CW WCDMA, UL WCDMA DL 1C WCDMA DL 4C LTE DL 1C LTE DL 4C –3 –35 –30 –25 –20 –15 –10 –5 0 RF INPUT POWER (dBm) 10 2.0 1.0 2.0 –1 Linearity Error Temperature Variation from 25°C at 2600MHz 1.4 0 –40 –35 –30 –25 –20 –15 –10 –5 0 RF INPUT POWER (dBm) 0 5581 G11 LINEARITY ERROR (dB) VOUT (V) 1.6 5 TA = 25°C 1 –2 –3 –40 –35 –30 –25 –20 –15 –10 –5 0 RF INPUT POWER (dBm) 2.5 25°C 85°C – 40°C –40°C –1 Output Voltage and Linearity Error at 2600MHz 1.8 85°C –2 5581 G10 2.0 LINEARITY ERROR (dB) 1.5 1.4 0 –40 –35 –30 –25 –20 –15 –10 –5 0 RF INPUT POWER (dBm) 3 2.0 LINEARITY ERROR (dB) VOUT (V) 1.6 Linearity Error vs RF Input Power, 2140MHz Modulated Waveforms LINEARITY ERROR (dB) 1.8 2.5 25°C 85°C – 40°C VARIATION (dB) 2.0 Linearity Error Temperature Variation from 25°C at 2140MHz CW WiMax OFDMA PREAMBLE WiMax OFDM BURST –3 –35 –30 –25 –20 –15 –10 –5 0 RF INPUT POWER (dBm) 5 10 5581 G18 5581fb For more information www.linear.com/LT5581 LT5581 TYPICAL PERFORMANCE CHARACTERISTICS Output Voltage and Linearity Error at 5800MHz 1.6 1.5 0.5 1.0 0 0.8 –0.5 0.6 –1.0 0.4 –1.5 0.2 –2.0 10 LINEARITY ERROR (dB) 1.0 1.2 5 3 3 2 2 1 85°C 0 –40°C –1 –2 –2.5 –3 –40 –35 –30 –25 –20 –15 –10 –5 0 RF INPUT POWER (dBm) 28 Supply Current vs Supply Voltage 1.8 20 28 29 30 31 32 SLOPE (mV/dB) 33 1.6 25°C 1.4 –40°C 1.2 34 0.8 2.6 3 3.4 3.8 4.2 4.6 5 5.4 SUPPLY VOLTAGE (V) 5581 G23 Logarithmic Intercept vs Frequency 5581 G24 Logarithmic Intercept Distribution vs Temperature 50 TA = 25°C TA = 85°C TA = 25°C TA = –40°C 40 DISTRIBUTION (%) –35 –40 –45 –50 85°C 1.0 5581 G22 –30 10 2.0 30 0 6 5 5 5581 G21 10 2 3 4 FREQUENCY (GHz) CW WiMax OFDM BURST –3 –35 –30 –25 –20 –15 –10 –5 0 RF INPUT POWER (dBm) 10 SUPPLY CURRENT (mA) DISTRIBUTION (%) 30 LOGARITHMIC INTERCEPT (dBm) SLOPE (mV/dB) 5 TA = 85°C TA = 25°C TA = –40°C 40 32 1 –1 Slope Distribution vs Temperature 50 TA = 25°C 0 0 5581 G20 Slope vs Frequency 26 1 –2 5581 G19 34 TA = 25°C 2.0 1.4 0 –40 –35 –30 –25 –20 –15 –10 –5 0 RF INPUT POWER (dBm) Linearity Error vs RF Input Power, 5.8GHz Modulated Waveforms LINEARITY ERROR (dB) 1.8 VOUT (V) 2.5 25°C 85°C – 40°C VARIATION (dB) 2.0 Linearity Error Temperature Variation from 25°C at 5800MHz 30 20 10 0 1 2 3 4 FREQUENCY (GHz) 6 5 0 –48 5581 G25 –47 –46 –45 –44 –43 –42 LOGARITHMIC INTERCEPT (dBm) –41 5581 G26 5581fb For more information www.linear.com/LT5581 7 LT5581 TYPICAL PERFORMANCE CHARACTERISTICS Output Voltage and Linearity Error vs VCC at 2140MHz Supply Current vs RF Input Power 16 2.0 TA = 25°C 1.8 12 VOUT (V) 10 8 6 4 2 0 0 5 –25 –20 –15 –10 –5 RF INPUT POWER (dBm) 10 1.0 1.2 0.5 1.0 0 0.8 –0.5 0.6 –1.0 0.4 –1.5 0.2 –2.0 0 –40 –35 –30 –25 –20 –15 –10 –5 0 RF INPUT POWER (dBm) 15 3.0 TA = 25°C OUTPUT VOLTAGE (V) RETURN LOSS (dB) –15 –20 2.5 RF & EN PULSE OFF 2.0 RF & EN PULSE ON RF & EN PULSE OFF 5 0 PIN = 10dBm PIN = 0dBm 1.5 –5 PIN = –10dBm 1.0 –10 PIN = –20dBm PIN = –30dBm 0.5 –0.5 2 3 4 5 6 FREQUENCY (GHz) L1, C1 = 0nH, 0.5pF L1, C1 = 2.2nH, 1.5pF L1, C1 = 0nH, 0pF L1, C1 = 1nH, 1.5pF L1, C1 = 0nH, 1pF 5581 G29 1 –15 –10 PIN = –20dBm 2.0 EN PULSE ON –25 4 TA = 25°C EN PULSE OFF 2 0 PIN = 10dBm 1.5 PIN = 0dBm –2 1.0 PIN = –10dBm –4 0.5 PIN = –30dBm –15 0 –20 10 20 30 40 50 60 70 80 90 100 TIME (µs) –0.5 PIN = –30dBm 0 OUTPUT VOLTAGE (V) –5 PIN = 0dBm 0.5 1 PIN = –20dBm ENABLE (V) 0 EN PULSE OFF 2.5 5 RF PULSE ENABLE (V) RF PULSE OFF PIN = –10dBm 1.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 TIME (ms) 3.0 10 PIN = 10dBm 1.5 0 Output Transient Response with CW RF and EN Pulse 3.0 TA = 25°C, VCC = 5V RF PULSE ON RF 2.5 PULSE OFF 2.0 –20 5581 G30 Output Transient Response OUTPUT VOLTAGE (V) 10 TA = 25°C, VCC = 5V 0 0 –2.5 RF PULSE ENABLE (V) –10 –25 –6 –8 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 TIME (ms) 5581 G31 8 10 Output Transient Response with RF and EN Pulse –5 0 5 5581 G28 Return Loss vs Frequency Reference in Figure 1 Test Circuit –30 1.5 1.4 5581 G27 0 2.0 3.3V 5V 1.6 LINEARITY ERROR (dB) SUPPLY CURRENT (mA) 14 2.5 TA = 25°C 1 –10 5581 G32 5581fb For more information www.linear.com/LT5581 LT5581 PIN FUNCTIONS V CC (Pin 1): Power Supply, 2.7V to 5.25V. V CC should be bypassed with a 0.1µF ceramic capacitor. EN (Pin 2): Chip Enable. A logic low or no-connect on the enable pin shuts down the part. A logic high enables the part. An internal 500k pull-down resistor ensures the part is off when the enable driver is in a three-state condition. VOUT (Pin 3): Detector Output. GND (Pins 4, 5, 6): Ground. CSQ (Pin 8): Optional Low Frequency Range Extension Capacitor. This pin is for frequencies below 250MHz. Use 0.01µF from pin to ground for 10MHz operation. Exposed Pad (Pin 9): Ground. The Exposed Pad must be soldered to the PCB. For high frequency operation, the backside ground connection should have a low inductance connection to the PCB ground, using many through-hole vias. See the layout information in the Applications Information section. RFIN (Pin 7): RF Input. Should be DC-blocked with coupling capacitor; 1000pF recommended. This pin has an internal 200Ω termination. BLOCK DIAGRAM 9 LT5581 7 EXPOSED PAD OUTPUT BUFFER 150kHz LPF RFIN 300Ω RMS DETECTOR BIAS 2 3 GND EN CSQ 8 VOUT VCC 1 4 5 6 5581 BD 5581fb For more information www.linear.com/LT5581 9 LT5581 TEST CIRCUIT C7 0.1µF VCC C6 100pF C5 OPT 1 EN 2 R3 0Ω VOUT C4 OPT 3 NC 4 CSQ VCC EN LT5581 GND VOUT GND RFIN GND GND 8 C3 0.01µF C2 1000pF 7 6 5 NC L1 2.2nH R2 68Ω RFIN C1 1.5pF NC 9 0.018" EE = 4.4 0.062" 0.018" PINS 4, 5, 6: OPTIONAL GROUND RF GND 5581 F01 DC GND REF DES VALUE SIZE PART NUMBER C6 100pF 0603 AVX 06033A101KAT2A FREQUENCY RANGE L1 C1 C7 0.1µF 0603 AVX 06033C104KAT2A 1GHz to 2.2GHz 2.2nH 1.5pF C3 0.01µF 0603 AVX 06033C103KAT2A 2GHz to 2.6GHz 1.2nH 1.5pF AVX 06033C102KAT2A 2.6GHz to 3.4GHz 0 1pF 3.8GHz to 5.5GHz 0 0.5pF 4.6GHz to 6GHz 0 0 C2 1000pF 0603 R2 68Ω 0603 RFIN MATCH Figure 1. Evaluation Circuit Schematic 10 5581fb For more information www.linear.com/LT5581 LT5581 APPLICATIONS INFORMATION OPERATION Table 1. RF Input Impedance To achieve an accurate average power measurement of the high crest factor modulated RF signals, the LT5581 combines a proprietary high speed power measurement subsystem with an internal 150kHz low pass averaging filter and an output voltage buffer in a completely integrated solution with minimal off-chip components. The resulting output voltage is directly proportional to the average RF input power in dBm. Figure 1 shows the evaluation circuit schematic, and Figures 2 and 3 show the associated board artwork. For best high frequency performance, it is important to place many ground vias directly under the package. FREQUENCY (MHz) INPUT IMPEDANCE (Ω) MAG ANGLE (°) 10 203.6-j5.5 0.606 –0.8 S11 50 199.5-j22.4 0.603 –3.4 100 191.7-j40.3 0.601 –6.4 200 171.1-j68.5 0.601 –12.3 400 121.8-j95.4 0.608 –24 500 100.2-j97.5 0.613 –29.8 800 56.8-j86.5 0.631 –46.5 900 48-j81.2 0.638 –51.8 1000 41.1-j76 0.645 –56.8 RF Input Matching 1500 22.2-j55 0.679 –79.5 The input resistance is about 205Ω. Input capacitance is 1.6pF. The impedance vs frequency of the RF input is detailed in Table 1. 2000 14.6-j41.4 0.710 –97.9 2100 13.6-j39.2 0.716 –101.2 2500 10.8-j32.1 0.737 –112.9 3000 8.6-j25 0.759 –125.7 3500 7.3-j19.4 0.774 –136.9 4000 6.6-j14.5 0.783 –147.1 5000 8.8-j9.6 0.709 –157.6 6000 6.4-j0 0.774 –179.9 5581 F02 Figure 2. Top Side of Evaluation Board 5581 F03 Figure 3. Bottom Side of Evaluation Board 5581fb For more information www.linear.com/LT5581 11 LT5581 APPLICATIONS INFORMATION A shunt 68Ω resistor can be used to provide a broadband impedance match at low frequencies up to 1.3GHz, and from 4.5GHz to 6GHz. As shown in Figure 4, a nominal broadband input match can be achieved up to 2.2GHz by using an LC matching circuit consisting of a series 2.2nH inductor (L1) and a shunt 1.5pF capacitor (C1). This match will maintain a return loss of about 10dB across the band. For matching at higher frequencies, values for L1 and C1 are listed in the table of Figure 1. The input reflection coefficient referenced to the RF input pin (with no external components) is shown on the Smith Chart in Figure 5. Alternatively, it is possible to match using an impedance transformation network by omitting R1 and transforming the 205Ω load to 50Ω. The resulting match, over a narrow band of frequencies, will improve sensitivity up to about 6dB maximum; the dynamic range remains the same. For example, by omitting R1 and setting L1 = 1.8nH and C1 = 3pF, a 2:1 VSWR match can be obtained from 1.95GHz to 2.36GHz, with a sensitivity improvement of 5dB. The RFIN input DC blocking capacitor (C2) and the CSQ bias decoupling capacitor (C3), can be adjusted for low VCC frequency operation. For input frequencies down to 10MHz, 0.01µF is needed at CSQ. For frequencies above 250MHz, the on-chip 20pF decoupling capacitor is sufficient, and CSQ may be eliminated as desired. The DC-blocking capacitor can be as large as 2200pF for 10MHz operation, or 100pF for 2GHz operation. A DC-blocking capacitor larger than 2200pF results in an undesirable RF pulse response on the falling edge. Therefore, for general applications, the recommended value for C2, is conservatively set at 1000pF. Output Interface The output buffer of the LT5581 is shown in Figure 6. It includes a push-pull stage with a series 300Ω resistor. The output stage is capable of sourcing and sinking 5mA of current. The output pin can be shorted to GND or VCC without damage, but going beyond VCC + 0.5V or GND – 0.5V may result in damage, as the internal ESD protection diodes will start to conduct excessive current. The residual ripple, due to RF modulation, can be reduced by adding external components RSS and CLOAD (R3 and C4 on the Evaluation Circuit Schematic in Figure 1) to LT5581 C3 0.01µF 8 RFIN (MATCHED) L1 205Ω C2 1000pF 7 C1 CSQ 20pF RFIN R1 68Ω 5581 F04 Figure 4. Simplified Circuit Schematic of the RF Input Interface 12 Figure 5. Input Reflection Coefficient 5581fb For more information www.linear.com/LT5581 LT5581 APPLICATIONS INFORMATION the output pin, to form an RC lowpass filter. The internal 300Ω resistor in series with the output pin enables filtering of the output signal with just the addition of CLOAD. Figure 7 shows the effect of the external filter capacitor on the residual ripple level for a 4-carrier WCDMA signal at 2.14GHz with –10dBm. Adding a 10nF capacitor to the output decreases the peak-to-peak output ripple from 135mVP-P to 50mVP-P. The filter –3dB corner frequency can be calculated with the following equation: 1 f = C 2π CLOAD (300 +RSS ) factor of 3, using a 0.047µF external filter capacitor. The average power in the preamble section is –10dBm, while the burst section has a 3dB lower average power. With the capacitor, the ripple in the preamble section is about 0.5dB peak-to-peak. The modulation used was OFDM (WiMAX 802.16-2004) MMDS band, 1.5MHz BW, with 256 size FFT and 1 burst at QPSK 3/4. Figure 9 shows how the peak-to-peak ripple decreases with increasing external filter capacitance value. Also shown is how the RF pulse response will have longer rise and fall times with the addition of this lowpass filter cap. Figure 8 shows the transient response for a 2.6GHz WiMAX signal, with preamble and burst ripple reduced by a 1.4 LT5581 VCC RSS 3 VOUT (FILTERED) OUTPUT VOLTAGE (V) VOUT 5581 F06 CLOAD TA = 25°C OUTPUT VOLTAGE (V) NO CAP 0.047µF 1.0 0.8 0.6 0.4 0.2 0 0 0.8 1.10 0.6 1.05 0.4 1.00 0.2 0.95 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 TIME (ms) 5581 F08 Figure 8. Residual Ripple for 2.6GHz WiMAX OFDM 802.16-2004 0 0.90 10 20 30 40 50 60 70 80 90 100 TIME (µs) 5581 F07 9 8 7 RIPPLE RISE FALL 1000 TA = 25°C 100 6 5 4 10 3 2 RISE TIME AND FALL TIME (µs) 1.2 1.15 Figure 7. Residual Ripple, Output Transient Response for RF Pulse with WCDMA 4-Carrier Modulation OUTPUT RIPPLE PEAK-TO-PEAK (dB) 1.4 1.0 0 Figure 6. Simplified Circuit Schematic of the Output Interface 1.20 OUTPUT VOLTAGE (V) 300Ω INPUT NO CAP 0.01µF 1.2 40µA 1.25 TA = 25°C 1 0 0.001 0.01 0.1 EXTERNAL CAPACITOR (µF) 1 1 5581 F09 Figure 9. Residual Ripple, Output Transient Times for RF Pulse with WCDMA 4-Carrier Modulation vs External Filter Capacitor C4 5581fb For more information www.linear.com/LT5581 13 LT5581 APPLICATIONS INFORMATION Figure 10 shows that rise time and fall time are strong functions of RF input power. Data is taken without the output filter capacitor. For a given RF modulation type—WCDMA, for example— the internal 150kHz filter provides nominal filtering of the residual ripple level. Additional external filtering occurs in the log domain, which introduces a systematic log error in relation to the signal’s crest factor, as shown in the following equation in dB.1 Error|dB = 10 • log10(r + (1 – r)10–CF/10) – CF • (r-1) Where CF is the crest factor and r is the duty cycle of the measurement (or number of measurements made at the peak envelope, divided by the total number of periodic 9 1 Steve Murray, “Beware of Spectrum Analyzer Power Averaging Techniques,” Microwaves & RF, Dec. 2006. 30 TA = 25°C FALL TIME 7 OUTPUT AC RIPPLE (dB) RISE TIME AND FALL TIME (µs) Figure 11 depicts the output AM modulation ripple as a function of modulation difference frequency for a 2-tone input signal at 2140MHz with –10dBm input power. The resulting deviation in the output voltage of the detector shows the effect of the internal 150kHz filter. 6 5 4 3 2 RISE TIME 1 0 –30 –25 –20 –15 –10 –5 0 25 –0.5 20 –1.0 15 –1.5 10 –2.0 5 –2.5 0 0.001 5 0 TA = 25°C INPUT POWER (dBm) 0.01 0.1 10 1 2-TONE FREQUENCY SEPARATION (MHz) 4.0 Figure 11. Output DC Voltage Deviation and Residual Ripple vs 2-Tone Separation Frequency 2.0 TA = 25°C 1.8 INTEGRATED NOISE (mVRMS) NOISE VOLTAGE (µVRMS / Hz) 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 0.1 0dBm –10dBm –20dBm –30dBm NO RF INPUT 1 100 10 FREQUENCY (kHz) TA = 25°C 1.6 1.4 1.2 0dBm –10dBm –20dBm –30dBm NO RF INPUT 1.0 0.8 0.6 0.4 0.2 1000 0 0.1 1 100 10 FREQUENCY (kHz) 1000 5581 F13 5581 F12 Figure 12. Output Voltage Noise Density 14 –3.0 5581 F11 5581 F10 Figure 10. RF Pulse Response Rise Time and Fall Time vs RF Input Power DEVIATION OF OUTPUT VOLTAGE (dB) 8 measurements in the measurement period). It is important to note that the CF refers to the 150kHz low pass filtered envelope of the signal. The error will depend on the statistics and bandwidth of the modulation signal in relation to the internal 150kHz filter. For example, in the case of WCDMA, simulations prove that it is possible to set the external filter capacitor corner frequency at 15kHz and only introduce an error less than 0.1dB. Figure 13. Integrated Output Voltage Noise 5581fb For more information www.linear.com/LT5581 LT5581 APPLICATIONS INFORMATION The output voltage noise density and integrated noise are shown in Figures 12 and 13, respectively, for various input power levels. Noise is a strong function of input level. There is roughly a 10dB reduction in the output noise level for an input level of 0dBm versus no input. It is important that the voltage applied to the EN pin never exceeds VCC by more than 0.5V, otherwise, the supply current may be sourced through the upper ESD protection diode connected at the EN pin. VCC LT5581 Enable Pin A simplified schematic of the EN pin is shown in Figure 14. To enable the LT5581, it is necessary to put greater than 2V on this pin. To disable or turn off the chip, this voltage should be below 0.3V. At an enable voltage of 3.3V, the pin draws roughly 20µA. If the EN pin is not connected, the chip is disabled through an internal 500k pull-down resistor. 2 EN 500k 300k 300k 5581 F14 Figure 14. Enable Pin Simplified Schematic 5581fb For more information www.linear.com/LT5581 15 LT5581 PACKAGE DESCRIPTION Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. DDB Package 8-Lead Plastic DFN (3mm × 2mm) (Reference LTC DWG # 05-08-1702 Rev B) 0.61 ±0.05 (2 SIDES) 0.70 ±0.05 2.55 ±0.05 1.15 ±0.05 PACKAGE OUTLINE 0.25 ±0.05 0.50 BSC 2.20 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 3.00 ±0.10 (2 SIDES) R = 0.115 TYP 5 R = 0.05 TYP 0.40 ±0.10 8 2.00 ±0.10 (2 SIDES) PIN 1 BAR TOP MARK (SEE NOTE 6) 0.56 ±0.05 (2 SIDES) 0.200 REF 0.75 ±0.05 0 – 0.05 4 0.25 ±0.05 1 PIN 1 R = 0.20 OR 0.25 × 45° CHAMFER (DDB8) DFN 0905 REV B 0.50 BSC 2.15 ±0.05 (2 SIDES) BOTTOM VIEW—EXPOSED PAD NOTE: 1. DRAWING CONFORMS TO VERSION (WECD-1) IN JEDEC PACKAGE OUTLINE M0-229 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE 16 5581fb For more information www.linear.com/LT5581 LT5581 REVISION HISTORY REV DATE DESCRIPTION A 4/10 Updated Note 2 in Electrical Characteristics Section PAGE NUMBER 4 B 8/15 Changed Enable Pin input voltage to 2V 15 5581fb 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 representation that the interconnectionFor of its circuits as described herein will not infringe on existing patent rights. more information www.linear.com/LT5581 17 LT5581 RELATED PARTS PART NUMBER DESCRIPTION RF Power Detectors LTC®5505 RF Power Detectors with >40dB Dynamic Range LTC5507 100kHz to 1000MHz RF Power Detector LTC5508 300MHz to 7GHz RF Power Detector LTC5509 300MHz to 3GHz RF Power Detector LTC5530 300MHz to 7GHz Precision RF Power Detector LTC5531 300MHz to 7GHz Precision RF Power Detector LTC5532 300MHz to 7GHz Precision RF Power Detector LT5534 50MHz to 3GHz Log RF Power Detector with 60dB Dynamic Range LTC5536 Precision 600MHz to 7GHz RF Power Detector with Fast Comparator Output LT5537 Wide Dynamic Range Log RF/IF Detector LT5538 75dB Dynamic Range 3.8GHz Log RF Power Detector Infrastructure LT5514 Ultralow Distortion, IF Amplifier/ADC Driver with Digitally Controlled Gain LT5517 40MHz to 900MHz Quadrature Demodulator LT5519 0.7GHz to 1.4GHz High Linearity Upconverting Mixer LT5520 1.3GHz to 2.3GHz High Linearity Upconverting Mixer LT5521 10MHz to 3700MHz High Linearity Upconverting Mixer LT5522 600MHz to 2.7GHz High Signal Level Downconverting Mixer LT5525 High Linearity, Low Power Downconverting Mixer LT5526 High Linearity, Low Power Downconverting Mixer LT5527 400MHz to 3.7GHz High Signal Level Downconverting Mixer LT5557 400MHz to 3.8GHz, 3.3V High Signal Level Downconverting Mixer LT5560 Ultralow Power Active Mixer LT5568 700MHz to 1050MHz High Linearity Direct Quadrature Modulator LT5572 1.5GHz to 2.5GHz High Linearity Direct Quadrature Modulator LT5575 800MHz to 2.7GHz High Linearity Direct Conversion I/Q Demodulator 18 Linear Technology Corporation COMMENTS 300MHz to 3GHz, Temperature Compensated, 2.7V to 6V Supply 100kHz to 1GHz, Temperature Compensated, 2.7V to 6V Supply 44dB Dynamic Range, Temperature Compensated, SC70 Package 36dB Dynamic Range, Low Power Consumption, SC70 Package Precision VOUT Offset Control, Shutdown, Adjustable Gain Precision VOUT Offset Control, Shutdown, Adjustable Offset Precision VOUT Offset Control, Adjustable Gain and Offset ±1dB Output Variation over Temperature, 38ns Response Time, Log Linear Response 25ns Response Time, Comparator Reference Input, Latch Enable Input, –26dBm to +12dBm Input Range Low Frequency to 1GHz, 83dB Log Linear Dynamic Range ±0.8dB Accuracy Over Temperature 850MHz Bandwidth, 47dBm OIP3 at 100MHz, 10.5dB to 33dB Gain Control Range 21dBm IIP3, Integrated LO Quadrature Generator 17.1dBm IIP3 at 1GHz, Integrated RF Output Transformer with 50Ω Matching, Single-Ended LO and RF Ports Operation 15.9dBm IIP3 at 1.9GHz, Integrated RF Output Transformer with 50Ω Matching, Single-Ended LO and RF Ports Operation 24.2dBm IIP3 at 1.95GHz, NF = 12.5dB, 3.15V to 5.25V Supply, Single-Ended LO Port Operation 4.5V to 5.25V Supply, 25dBm IIP3 at 900MHz, NF = 12.5dB, 50Ω Single-Ended RF and LO Ports Single-Ended 50Ω RF and LO Ports, 17.6dBm IIP3 at 1900MHz, ICC = 28mA 3V to 5.3V Supply, 16.5dBm IIP3, 100kHz to 2GHz RF, NF = 11dB, ICC = 28mA, –65dBm LO-RF Leakage IIP3 = 23.5dBm and NF = 12.5dBm at 1900MHz, 4.5V to 5.25V Supply, ICC = 78mA, Conversion Gain = 2dB IIP3 = 23.7dBm at 2600MHz, 23.5dBm at 3600MHz, ICC = 82mA at 3.3V 10mA Supply Current, 10dBm IIP3, 10dB NF, Usable as Up- or Down-Converter. 22.9dBm OIP3 at 850MHz, –160.3dBm/Hz Noise Floor, 50Ω, 0.5VDC Baseband Interface, 3-Ch CDMA2000 ACPR = –71.4dBc at 850MHz 21.6dBm OIP3 at 2GHz, –158.6dBm/Hz Noise Floor, High-Ohmic 0.5VDC Baseband Interface, 4-Ch W-CDMA ACPR = –67.7dBc at 2.14GHz 50Ω, Single-Ended RF and LO Inputs. 28dBm IIP3 at 900MHz, 13.2dBm P1dB, 0.04dB I/Q Gain Mismatch, 0.4° I/Q Phase Mismatch 1630 McCarthy Blvd., Milpitas, CA 95035-7417 For more information www.linear.com/LT5581 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com/LT5581 5581fb LT 0815 REV B • PRINTED IN USA LINEAR TECHNOLOGY CORPORATION 2008