Precision 3MHz to 7GHz RF Detector with Shutdown and Gain Adjustment FEATURES Temperature Compensated Internal Schottky Diode RF Detector Wide Input Frequency Range: 3MHz to 7GHz* Wide Input Power Range: 32dBm to dbm Buffered Detector Output with External Gain Control Low Starting Voltage: 2mV ±35mV for Gain = 2X Wide V CC Range of 2.7V to 6V Low Operating Current: 5µA Low Shutdown Current: <2µA Available in a Low Profile (mm) SOT-23 Package APPLICATIO S U 82.a, 82.b, 82.g, 82.5, 82.6 Multimode Mobile Phone Products Optical Data Links Wireless Data Modems Wireless and Cable Infrastructure RF Power Alarm Envelope Detector DESCRIPTIO U The LTC 553 is an RF power detector for RF applications operating in the 3MHz to 7GHz range. A temperature compensated Schottky diode peak detector and buffer amplifier are combined in a small ThinSOT TM package. The supply voltage range is optimized for operation from a single lithium-ion cell or 3xNiMH. The RF input voltage is peak detected using an on-chip Schottky diode. The detected voltage is buffered and supplied to the V OUT pin. The output buffer gain is set via external resistors. A power saving shutdown mode reduces current to less than 2µA. The LTC553 operates with input power levels from 32dBm to dbm., LTC and LT are registered trademarks of Linear Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation. *Higher frequency operation is achievable with reduced performance. Consult factory for more information. TYPICAL APPLICATIO RF INPUT U 3MHz to 7GHz RF Power Detector 33pF LTC553 V 6 RF IN CC 2 GND 3 DISABLE ENABLE SHDN V OUT V M 553 TA 5 4 R A R B pf VCC.µF 36 2 2 6 2 4 Output Voltage vs RF Input Power 3MHz MHz 2MHz 3MHz 4MHz 5MHz 6MHz 7MHz 32 28 24 2 6 2 8 4 4 8 553 TA2
ABSOLUTE AXI U RATI GS (Note ) W W W V CC, V OUT, SHDN, V M....3V to 6.5V RF IN Voltage...(V CC ±.5V) to 7V RF IN Power (RMS)... 2dBm I VOUT... 5mA Operating Temperature Range (Note 2).. 4 C to 85 C Maximum Junction Temperature... 25 C Storage Temperature Range... 65 C to 5 C Lead Temperature (Soldering, sec)... 3 C U U U W PACKAGE/ORDER I FOR ATIO RF IN GND 2 SHDN 3 TOP VIEW 6 V CC 5 V OUT 4 V M S6 PACKAGE 6-LEAD PLASTIC TSOT-23 T JMAX = 25 C, θ JA = 25 C/W ORDER PART NUMBER LTC553ES6 S6 PART MARKING LBDX Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at., SHDN = V CC = HI, SHDN = V = LO, RF Input Signal is Off, R A = R B = k, SHDN = HI unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS V CC Operating Voltage 2.7 6 V I VCC Operating Current I VOUT = ma.5.7 ma I VCC Shutdown Current SHDN = LO. 2 µa V OUT (No RF Input) R LOAD = 2k 85 to 4 55 mv SHDN = LO mv V OUT Output Current V OUT =.75V, V CC = 2.7V, V OUT < mv 2 4 ma V OUT Enable Time SHDN = LO to HI, C LOAD = 33pF, R LOAD = 2k 8 2 µs V OUT Bandwidth C LOAD = 33pF, R LOAD = 2k (Note 4) 2 MHz V OUT Load Capacitance (Notes 6, 7) 33 pf V OUT Slew Rate V RFIN = V Step, C LOAD = 33pF, R LOAD = 2k (Note 3) 3 V/µs V OUT Noise V CC = 3V, Noise BW =.5MHz, 5Ω RF Input Termination mv P-P V M Voltage Range V CC.8V V V M Input Current.5.5 µa SHDN Voltage LO, Chip Disabled V CC = 2.7V to 6V.35 V SHDN Voltage HI, Chip Enabled V CC = 2.7V to 6V.4 V SHDN Input Current SHDN = 3.6V 22 36 µa RF IN Input Frequency Range (Note 8) 3 to 7 MHz RF IN Input Power Range RF Frequency = 3MHz to 7GHz (Note 5, 6) V CC = 2.7V to 6V 32 to dbm RF IN AC Input Resistance F = MHz, Pin = 25dBm 22 Ω RF IN Input Shunt Capacitance F = MHz, Pin = 25dBm.65 pf Note : Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: Specifications over the 4 C to 85 C operating temperature range are assured by design, characterization and correlation with statistical process controls. Note 3: The rise time at V OUT is measured between.3v and 2.3V. Note 4: Bandwidth is calculated based on the % to 9% rise time 2 equation: BW =.35/rise time. Note 5: RF performance is tested at MHz Note 6: Guaranteed by design. Note 7: Capacitive loading greater than this value may result in circuit instability. Note 8: Higher frequency operation is achievable with reduced performance. Consult factory for more information.
TYPICAL PERFOR A CE CHARACTERISTICS UW VOUT OUTPUT VOLTAGE (mv) 3 25 2 5 Output Voltage vs Supply Voltage (RF Input Signal Off) SUPPLY CURRENT (µa) 5 48 46 44 Supply Current vs Supply Voltage (RF Input Signal Off) VOUT OUTPUT VOLTAGE (mv) 56 4 4 6 V OUT vs RF Input Power and V CC MHz V CC = 6V V CC = 5V V CC = 4V V CC = 3V 2.5 3. 3.5 4. 4.5 5. 5.5 6. SUPPLY VOLTAGE V CC (V) 42 2.5 3. 3.5 4. 4.5 5. 5.5 6. SUPPLY VOLTAGE V CC (V) 32 28 24 2 6 2 8 4 4 8 2 553 G 553 G2 553 G3 36 2 2 6 2 4 3MHz GAIN =2 32 28 24 2 6 2 8 4 4 8 553 G4 VOUT OUTPUT VOLTAGE (mv) 36 2 2 6 2 4 MHz GAIN =2 32 28 24 2 6 2 8 4 4 8 553 G5 VOUT OUTPUT VOLTAGE (mv) 36 2 2 6 2 4 2MHz 32 28 24 2 6 2 8 4 4 8 553 G6 36 3MHz 36 4MHz 36 5MHz 2 2 6 2 4 2 2 6 2 4 2 2 6 2 4 32 28 24 2 6 2 8 4 4 8 553 G7 32 28 24 2 6 2 8 4 4 8 553 G8 32 28 24 2 6 2 8 4 4 8 553 G9 3
TYPICAL PERFOR A CE CHARACTERISTICS U W 36 6MHz 36 7MHz 2 2 6 2 4 2 2 6 2 4 32 28 24 2 6 2 8 4 4 8 553 G 32 28 24 2 6 2 8 4 4 8 553 G 36 2 2 6 2 4 3MHz GAIN = 4 36 2 2 6 2 4 MHz GAIN = 4 32 28 24 2 6 2 8 4 4 553 G2 32 28 24 2 6 2 8 4 4 553 G3 4
TYPICAL PERFOR A CE CHARACTERISTICS U W 3MHz MHz 2MHz V OUT SLOPE (mv/db) VOUT SLOPE (mv/db) VOUT SLOPE (mv/db) 3 25 2 5 5 5 3 25 2 5 5 5 3 25 2 5 5 5 553 G4 553 G5 553 G6 3MHz 4MHz 5MHz VOUT SLOPE (mv/db) VOUT SLOPE (mv/db) VOUT SLOPE (mv/db) 3 25 2 5 5 5 3 25 2 5 5 5 3 25 2 5 5 5 553 G7 553 G8 553 G9 6MHz 7MHz VOUT SLOPE (mv/db) V OUT SLOPE (mv/db) 3 25 2 5 5 5 3 25 2 5 5 5 553 G2 553 G2 5
TYPICAL PERFOR A CE CHARACTERISTICS UW RF IN Input Impedance (Pin = dbm,, ) FREQUENCY RESISTANCE REACTANCE (GHz) (Ω) (Ω).3 29.45 36.22.5 234.4 62.54.7 78.25 7.53.9 37.3 59.89. 9.7 47.57.3 86.3 36.8.5 68.65 2.74.7 57.48 7.6.9 49.79 96.72 2. 43.56 86.7 2.3 38.67 77.9 2.5 34.82 7.3 2.7 3.68 62.86 2.9 29.3 56. 3. 27.7 49.83 3.3 25.73 44.24 3.5 24.56 39.74 3.7 23.8 35.35 3.9 22.3 3.62 4. 2.73 26.88 4.3 9.88 22.3 4.5 9.4 8.23 4.7 9.5 4.25 4.9 9.8.2 5. 9.55 6.3 5.3 2.85 2.84 5.5 2.94.49 5.7 2.6.7 5.9 9.29 2.99 6. 8.69 6.6 6.3 8.53.39 6.5 8.74 4.35 6.7 9.79 7.9 6.9 9.75 2.77 7. 9.99 22.47 S Forward Reflection Impedance.3GHz-7.GHz 553 TA3 558 TA3 6
TYPICAL PERFOR A CE CHARACTERISTICS U W RF IN Input Impedance (Pin = 25dBm,, ) FREQUENCY RESISTANCE REACTANCE (GHz) (Ω) (Ω).3 26.45 76.47.5 9.63 98.28.7 6.98 2.3.9 33.7.53. 3.8 9.5.3 94.55 7.8.5 75.33 98.5.7 63.52 88.9.9 55.9 8.5 2. 48.64 72.23 2.3 43.73 64.8 2.5 39.7 58.3 2.7 36.47 52.27 2.9 33.69 46.77 3. 3.6 4.25 3.3 29.78 36.6 3.5 28.27 32.39 3.7 26.63 28.2 3.9 26.2 23.97 4. 24.2 2.75 4.3 23.28 6.69 4.5 22.6 2.77 4.7 22.2 9.8 4.9 22.5 5.24 5. 22.6.58 5.3 23.9.53 5.5 24.97 2.62 5.7 23.5 4. 5.9 22.25 6.94 6. 2.57.62 6.3 2.43 4.2 6.5 2.69 7.77 6.7 22.68 2.24 6.9 22.8 24.2 7. 23.7 25.56 S Forward Reflection Impedance.3GHz-7.GHz 553 TA4 558 TA4 7
PI FU CTIO S U U U RF IN (Pin ): RF Input Voltage. Referenced to V CC. A coupling capacitor must be used to connect to the RF signal source. The frequency range is 3MHz to 7GHz. This pin has an internal 5Ω termination, an internal Schottky diode detector and a peak detector capacitor. GND (Pin 2): Ground. SHDN (Pin 3): Shutdown Input. A logic low on the SHDN pin places the part in shutdown mode. A logic high enables the part. SHDN has an internal 6k pulldown resistor to ensure that the part is in shutdown when no input is applied. In shutdown V OUT is connected to ground via a 28Ω resistor. V M (Pin 4): Negative Input to Buffer Amplifier. V OUT (Pin 5): Detector Output. V CC (Pin 6): Power Supply Voltage, 2.7V to 6V. V CC should be bypassed appropriately with ceramic capacitors. BLOCK DIAGRA W RF SOURCE V CC 6 BIAS SHUTDOWN RF IN 5Ω 5Ω + SD BUFFER 5 V OUT 3k 25pF 24k + RF DET SD 5µA 5µA 4k SD 8Ω Ω 4 V M GND 2 6k 3 SHDN 553 BD 8
APPLICATIO S I FOR Operation ATIO U W U U The LTC553 RF detector integrates several functions to provide RF power detection over frequencies ranging from 3MHz to 7GHz. These functions include an internal frequency compensated buffer amplifier, an RF Schottky diode peak detector and level shift amplifier to convert the RF input signal to DC and a delay circuit to avoid voltage transients at V OUT when powering up. The LTC553 has both shutdown and gain setting capabilities. Buffer Amplifier The output buffer amplifier is capable of supplying typically 4mA into a load. The negative terminal V M is brought out to a pin for gain selection. External resistors connected between V OUT and V M (R A ) and V M to ground (R B ) will set the amplifier gain. GAIN = + R R A B The amplifier is unity gain stable; however a minimum gain of two is recommended to improve low output voltage accuracy. The amplifier bandwidth is 2MHz for a gain of 2. For increased gain applications, the bandwidth is reduced according to the formula: 4MHz RB BANDWIDTH = = 4MHz ( GAIN) ( R + R ) A capacitor can be placed across the feedback resistor RA to shape the frequency response. In addition the amplifier can be used as a comparator. V M can be connected to a reference voltage. When the internal detector voltage (which is connected to the positive input of the buffer amplifier) exceeds the external voltage of V M, V OUT will switch high. RF Detector The internal RF Schottky diode peak detector and level shift amplifier converts the RF input signal to a low frequency signal. The detector demonstrates excellent efficiency and linearity over a wide range of input power. The Schottky diode is biased at about 55µA and drives a 25pF internal peak detector capacitor. Shutdown The part is in shutdown mode when SHDN is low. The supply current is reduced to < 2µA and V OUT is shorted to ground via a 28Ω resistor. When SHDN is asserted high, the part is enabled after about 8µs. A B Demo Board Schematic RF IN C4 LTC553ES6 39pF RF IN V CC 6 C2 pf V CC 2.7V TO 6V C.µF V CC SHDN R (OPT) R2 22k 2 3 GND V OUT SHDN V M 5 4 R3 k R4 k V OUT C3 (OPT) 553 DB 9
APPLICATIO S I FOR ATIO Applications U W U U The LTC553 can be used as a self-standing signal strength measuring receiver for a wide range of input signals from 32dBm to dbm for frequencies from 3MHz to 7GHz. Operation at higher frequencies is achievable. Consult factory for more information. The LTC553 can be used as a demodulator for AM and ASK modulated signals with data rates up to 2MHz. Depending on specific application needs, the RSSI output can be split between two branches, providing AC-coupled data (or audio) output and DC-coupled RSSI output for signal strength measurements and AGC. The LTC553 can be used for RF power detection and control. Figure is an example of transmitter power control, using the LTC553 with a capacitive tap to the power amplifier. A.5pF capacitor (C) followed by a 2Ω resistor (R) forms a coupling circuit with about 2dB loss at 9MHz referenced to the LTC553 RF input pin. In the actual product implementation, component values for the capacitive tap may be different depending on parts placement, PCB parasitics and parameters of the antenna. LTC553ES6 RF IN V CC 6.µF Li-Ion Tx PA MODULE CELL BAND R 2Ω % C.5pF ±.5pF DIPLEXER 2 GND V OUT 5 DISABLE ENABLE 3 SHDN V M 4 R2 PCS BAND R3 MOBILE PHONE DSP VPC BSE 553 F Figure. Mobile Phone Tx Power Control Application with a Capacitive Tap
PACKAGE DESCRIPTIO U S6 Package 6-Lead Plastic TSOT-23 (Reference LTC DWG # 5-8-636).62 MAX.95 REF 2.9 BSC (NOTE 4).22 REF 3.85 MAX 2.62 REF.4 MIN 2.8 BSC.5.75 (NOTE 4) PIN ONE ID RECOMMENDED SOLDER PAD LAYOUT PER IPC CALCULATOR.95 BSC.3.45 6 PLCS (NOTE 3).8.9.2 BSC DATUM A. MAX...3.5 REF.9.2.9 BSC (NOTE 3) S6 TSOT-23 32 NOTE:. DIMENSIONS ARE IN MILLIMETERS 2. DRAWING NOT TO SCALE 3. DIMENSIONS ARE INCLUSIVE OF PLATING 4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR 5. MOLD FLASH SHALL NOT EXCEED.254mm 6. JEDEC PACKAGE REFERENCE IS MO-93 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 interconnection of its circuits as described herein will not infringe on existing patent rights.
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