LT5537

LT5537 - Wide Dynamic Range RF/IF Log Detector

Document overview

• Manufacturer or author: Linear Technology Corporation
• PDF pages: 16

Technical content

■ Linear-to-Log Signal Level Conversion ■ Received Signal Strength Indication (RSSI) ■ RF Power Control ■ RF/IF Power Detection ■ Receiver RF/IF Gain Control ■ Envelope Detection ■ ASK Receiver Wide Dynamic Range RF/IF Log Detector ■ Low Frequency to 1000MHz Operation ■ 83dB Dynamic Range with ±1dB Nonlinearity at 200MHz ■ Sensitivity –76dBm or Better at 200MHz ■ Log-Linear Transfer Slope of 20mV/dB ■ Supply Voltage Range: 2.7V to 5.25V ■ Supply Current: 13.5mA at 3V ■ Tiny 8-Lead (3mm × 2mm) DFN Package FEATURES DESCRIPTIO U APPLICATIO SU TYPICAL APPLICATIO U , LTC and LT are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. The LT 5537 is a wide dynamic range RF/IF detector, operational from below 10MHz to 1000MHz. The lower limit of the operating frequency range can be extended to near DC by the use of an external capacitor. The input dynamic range at 200MHz with ±3dB nonlinearity is 90dB (from –76dBm to 14dBm, single-ended 50Ω input). The detector output voltage slope is nominally 20mV/dB, and the typical temperature coefficient is 0.01dB/°C at 200MHz. OFFSET CANCELLATION DETECTOR CELLS EXPOSED PAD BANDGAP REFERENCE AND BIASING OUTPUT BUFFER ENBL

3 IN–

2 IN+

CAP– OUT

5537 TA01a

1µF 1nF 7.2k INPUT POWER (dBm) –80 VOUT (V) LINEARITY ERROR (dB) 0.4 0.8 1.2 1.6 2.0 2.4 –40°C –60 –40 –20 0

5537 TA01b

85°C 25°C VCC = ENBL = 3V Output Voltage, Linearity Error vs Input Power at 200MHz

(Note 1) Operating Ambient Temperature Range .. – 40°C to 85°C ABSOLUTE AXI U RATI GSW WW U Consult LTC Marketing for parts specified with wider operating temperature ranges. PACKAGE/ORDER I FOR ATIOUU W LT5537EDDB ORDER PART NUMBER DDB PART MARKING LBJR θJA = 76°C/W EXPOSED PAD (PIN 9) SHOULD BE SOLDERED TO PCB TOP VIEW DDB PACKAGE 8-LEAD (3mm /KB4 2mm) PLASTIC DFN 1ENBL IN IN– CAP+ OUT VEE VCC CAP– Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF Lead Free Part Marking: http://www.linear.com/leadfree/ VCC = 3V, ENBL = 3V, TA = 25°C, unless otherwise specified. (Notes 3, 4)ELECTRICAL CHARACTERISTICS PARAMETER CONDITIONS MIN TYP MAX UNITS Signal Input Input Frequency Range (Note 5) 10 to 1000 MHz Maximum Input Power for Monotonic Output 50 Ω Termination 200MHz 14.0 dBm 600MHz 11.6 dBm 1GHz 9.4 dBm DC Common Mode Voltage VCC – 0.4 V Small-Signal Impedance Measured at 200MHz 1.73k Ω //1.45pF f = 10MHz Linear Dynamic Range ±3dB Error 88.8 dB ±1dB Error 72.5 dB Slope R1 = 33k (Note 8) 19.6 mV/dB Intercept V OUT = 0V, Extrapolated –97 dBm Sensitivity (Notes 3, 7) –76.7 dBm Temperature Coefficient P IN = –20dBm –0.007 dB/ °C f = 50MHz Linear Dynamic Range ±3dB Error 90.6 dB ±1dB Error 81.0 dB Slope R1 = 33k (Note 8) 20 mV/dB Intercept V OUT = 0V, Extrapolated –96 dBm Sensitivity (Notes 3, 7) –77.2 dBm Temperature Coefficient P IN = –20dBm –0.005 dB/ °C

VCC = 3V, ENBL = 3V, TA = 25°C, unless otherwise specified. (Notes 3, 4)ELECTRICAL CHARACTERISTICS PARAMETER CONDITIONS MIN TYP MAX UNITS f = 100MHz Linear Dynamic Range ±3dB Error 90.5 dB ±1dB Error 82.8 dB Slope R1 = 33k (Note 8) 20.3 mV/dB Intercept V OUT = 0V, Extrapolated –95 dBm Sensitivity (Notes 3, 7) –77 dBm Temperature Coefficient P IN = –20dBm –0.004 dB/ °C f = 200MHz Linear Dynamic Range ±3dB Error 90.3 dB ±1dB Error 83.5 dB Slope R1 = 33k (Note 8) 21.2 mV/dB Intercept V OUT = 0V, Extrapolated –94 dBm Sensitivity (Notes 3, 7) –76.4 dBm Temperature Coefficient P IN = –20dBm 0.010 dB/ °C f = 400MHz Linear Dynamic Range ±3dB Error 88.2 dB ±1dB Error 70.8 dB Slope R1 = 33k (Note 8) 23.1 mV/dB Intercept V OUT = 0V, Extrapolated –91 dBm Sensitivity (Notes 3, 7) –75.3 dBm Temperature Coefficient P IN = –20dBm 0.019 dB/ °C f = 600MHz Linear Dynamic Range ±3dB Error 85.8 dB ±1dB Error 72.5 dB Slope R1 = 33k (Note 8) 25.2 mV/dB Intercept V OUT = 0V, Extrapolated –89 dBm Sensitivity (Notes 3, 7) –74.1 dBm Temperature Coefficient P IN = –20dBm 0.026 dB/ °C f = 1GHz Linear Dynamic Range ±3dB Error 63.5 dB ±1dB Error 51.7 dB Slope R1 = 33k (Note 8) 31.4 mV/dB Intercept V OUT = 0V, Extrapolated –80 dBm Sensitivity (Notes 3, 7) –69.2 dBm Temperature Coefficient P IN = –20dBm 0.031 dB/ °C Output Starting Voltage No RF Signal Present 0.4 V Response Time Input from –30dBm to 0dBm, C LOAD = 2.5pF 110 ns Baseband Modulation Bandwidth Output Load Capacitance = 2.5pF 6 MHz Shutdown Mode ENBL = High (On) 1V ENBL = Low (Off) 0.3 V ENBL Input Current V ENBL = 3V 100 µA VENBL = 0V 0 µA Turn-On Time 100 µs Turn-Off Time 100 µs

TYPICAL PERFOR A CE CHARACTERISTICS UW 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: Maximum differential AC input voltage between IN+ and IN– is 4V peak. Equivalent to 22dBm with 50Ω input impedance or 16dBm with 200Ω input impedance (1:4 transformer used). Note 3: Tests are performed as shown in the configuration of Figure 13. Note 4: Specifications over the –40°C to 85°C temperature range are assured by design, characterization and correlation with statistical process control. Note 5: Operation at lower frequency is possible as described in the “Low Frequency Operation” section in Applications Information. Note 6: The maximum output voltage is limited to approximately VCC – 0.6V. Either the output slope should be reduced or input power level should be limited in order to avoid saturating the output circuit when VCC < 3V. See discussion in “Dynamic Range” section. Note 7: Sensitivity is defined as the minimum input power required for the output voltage to be within 3dB of the ideal log-linear transfer curve. Sensitivity can be improved by as much as 10dB by using a narrowband input impedance transformation network. See discussion in “Input Matching” section. Note 8: The output slope is adjustable using an external pull-down resistor (R1). See Applications Information for description of the output circuit. SUPPLY VOLTAGE (V) 2.5 SUPPLY CURRENT (mA) 3.0 3.5 4.0 4.5

5537 G02

5.0 5.5 TA = 85°C TA = 25°C TA = –40°C RF INPUT SIGNAL OFF ENBL = VCC SUPPLY VOLTAGE (V) 2.5 ENBL CURRENT (µA) 100 150 200 250 3.0 3.5 4.0 4.5

5537 G03

5.0 5.5 TA = 85°C TA = –40°C TA = 25°C RF INPUT SIGNAL OFF ENBL = V CC Supply Current vs Supply Voltage ENBL Current vs Supply Voltage VCC = 3V, ENBL = 3V, TA = 25°C, unless otherwise specified. (Notes 3, 4)ELECTRICAL CHARACTERISTICS PARAMETER CONDITIONS MIN TYP MAX UNITS Power Supply Supply Voltage (Note 6) 2.7 5.25 V Supply Current V CC = 3V 10 13.5 15 mA Shutdown Current ENBL = Low 500 µA

TYPICAL PERFOR A CE CHARACTERISTICS UW VOUT Variation vs Input Power at 50MHz Output Voltage, Linearity Error vs Input Power at 100MHz VOUT Variation vs Input Power at 100MHz INPUT POWER (dBm) –80 VOUT VARIATION (dB) –60 –40 –20 0

5537 G07

NORMALIZED AT 25°C VCC = ENBL = 3V 85°C –40°C INPUT POWER (dBm) –80 VOUT (V) LINEARITY ERROR (dB) 0.4 0.8 1.2 1.6 2.0 2.4 –40°C –60 –40 –20 0

5537 G08

25°C VCC = ENBL = 3V 85°C INPUT POWER (dBm) –80 VOUT VARIATION (dB) –60 –40 –20 0

5537 G09

NORMALIZED AT 25°C VCC = ENBL = 3V 85°C –40°C Output Voltage, Linearity Error vs Input Power at 200MHz VOUT Variation vs Input Power at 200MHz Typical Detector Characteristics INPUT POWER (dBm) –80 VOUT (V) LINEARITY ERROR (dB) 0.4 0.8 1.2 1.6 2.0 2.4 –40°C –60 –40 –20 0

5537 G10

85°C 25°C VCC = ENBL = 3V INPUT POWER (dBm) –80 VOUT VARIATION (dB) –60 –40 –20 0

5537 G11

NORMALIZED AT 25°C VCC = ENBL = 3V 85°C –40°C INPUT POWER (dBm) –80 VOUT (V) 1.6 2.0 2.4

5537 G12

1.2 0.8 0.4 –60 –40 –20 20 TA = 25°C 200MHz ENBL = VCC Output Voltage, Linearity Error vs Input Power at 10MHz VOUT Variation vs Input Power at 10MHz INPUT POWER (dBm) –80 VOUT (V) LINEARITY ERROR (dB) 0.4 0.8 1.2 1.6 2.0 2.4 –40°C –60 –40 –20 0

5537 G04

85°C 25°C VCC = ENBL = 3V Output Voltage, Linearity Error vs Input Power at 50MHz INPUT POWER (dBm) –80 VOUT VARIATION (dB) –40°C –60 –40 –20 0

5537 G05

85°C NORMALIZED AT 25°C VCC = ENBL = 3V INPUT POWER (dBm) –80 VOUT (V) LINEARITY ERROR (dB) 0.4 0.8 1.2 1.6 2.0 2.4 –40°C –60 –40 –20 0

5537 G06

25°C VCC = ENBL = 3V 85°C

TYPICAL PERFOR A CE CHARACTERISTICS UW VOUT Variation vs Input Power at 600MHz Output Voltage, Linearity Error vs Input Power at 1GHz VOUT Variation vs Input Power at 1GHz INPUT POWER (dBm) –80 VOUT VARIATION (dB) –60 –40 –20 0

5537 G16

NORMALIZED AT 25°C VCC = ENBL = 3V 85°C –40°C INPUT POWER (dBm) –80 VOUT (V) LINEARITY ERROR (dB) 0.5 1.0 1.5 2.0 2.5 3.0 –40°C –60 –40 –20 0

5537 G17

85°C 25°C VCC = ENBL = 3V INPUT POWER (dBm) –80 VOUT VARIATION (dB) –60 –40 –20 0

5537 G18

NORMALIZED AT 25°C VCC = ENBL = 3V 85°C –40°C Output Voltage Distribution vs Temperature at –50dBm Output Voltage Distribution vs Temperature at –20dBm Output Voltage, Linearity Error vs Input Power at 400MHz VOUT Variation vs Input Power at 400MHz INPUT POWER (dBm) –80 VOUT (V) LINEARITY ERROR (dB) 0.5 1.0 1.5 2.0 2.5 3.0 –40°C –60 –40 –20 0

5537 G13

85°C 25°C VCC = ENBL = 3V INPUT POWER (dBm) –80 VOUT VARIATION (dB) –60 –40 –20 0 NORMALIZED AT 25°C VCC = ENBL = 3V 85°C –40°C INPUT POWER (dBm) –80 VOUT (V) LINEARITY ERROR (dB) 0.5 1.0 1.5 2.0 2.5 3.0 –40°C –60 –40 –20 0

5537 G15

85°C 25°C VCC = ENBL = 3V Output Voltage, Linearity Error vs Input Power at 600MHz OUTPUT VOLTAGE (V) DISTRIBUTION (%)

5537 G19

RF PIN = –50dBm at 200MHz VCC = ENBL = 3V 25°C –40°C 85°C OUTPUT VOLTAGE (V) DISTRIBUTION (%)

5537 G20

RF PIN = –20dBm at 200MHz VCC = ENBL = 3V 25°C –40°C 85°C

ENBL (Pin 1): Enable Pin. When the input voltage is higher than 1V, the circuit is ON. When the input voltage is less than 0.3V, or this pin is not connected, the chip is disabled (OFF). IN+, IN– (Pins 2, 3): Differential Signal Input Pins. These pins are internally biased to V CC – 0.4V. The impedance between IN+ and IN– is approximately 1.73kΩ//1.45pF at 200MHz. The input pins should be AC coupled. CAP+, CAP– (Pins 4, 5): External Filter Capacitor Pins. The minimum RF input frequency can be lowered by adding an optional external capacitor between CAP+ and CAP–. VCC (Pin 6): Power Supply Pin. This pin should be decoupled using 1000pF and 0.1µF capacitors. VEE (Pin 7): Ground pin. OUT (Pin 8): Output pin. Exposed Pad (Pin 9): Should be connected to PCB ground. OFFSET CANCELLATION DETECTOR CELLS BANDGAP REFERENCE AND BIASING OUTPUT BUFFER ENBL CAP– OUT 5537 BD VEE CAP+7k EXPOSED PAD VCC 7.2k

mined by the total load resistance at the output terminal. connected between the output pin and ground. the output time domain voltage ripple. Figure 1. Slope Variation over Frequency Figure 2. Simplified Output Circuit

5537 F01

5537 F02

5537 F04

Figure 3. Simplified Input Circuit Figure 4. Input Admittance Figure 5. Differential Input Matching to 200Ω 200MHz, the input is equivalent to 1.73k//1.45pF (Table 1). Table 1. Parallel Equivalent RC of the LT5537 Input a (3dB error) sensitivity of –82.4dBm at 200MHz.

5537 F06

5537 F10

Figure 7. Measured Output with RIN = 264Ω serve to improve the sensitivity of the logarithmic detector. ance or sensitivity requirements. Table 2. Matching Network Component Values for 200MHz Figure 6. Input Matching Network

5537 F07

ment of 10dB compared with a simple 50Ω termination. The input return loss is 25dB at the design frequency. Bandwidth for better than 10dB return loss is 18MHz.

5537 F14

Figure 8. Timing Test Setup Figure 9. Response Time (–30dBm to –60dBm)

coupled, the high overall gain requires DC offset control. by the bandwidth of the offset cancellation feedback loop.

5537 F16

Figure 10. Offset Cancellation Loop Filter and the input termination resistance leads to the zero. also sets the lower corner frequency of the signal path). designs suitable for different applications. phase margin (PM) of 75 degrees. Table 3. Application Design Examples

5537 F17

Figure 11. 10kHz Operation purpose design which can operate as low as 1.3MHz. well damped response to any input biasing transients. sponse of this circuit at 10kHz is plotted in Figure 11. tor output, degrading the overall response time of the chip. transient, whichever occurs first. this purpose, but will not operate below 20MHz.

Figure 13. Application Board Schematic Figure 14. Layout of the Evalulation Board the enable circuit biases the chip up for normal operation. Figure 12. Equivalent ENBL Input Circuit

5537 F19

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 represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. UPACKAGE DESCRIPTIO 8-Lead Plastic DFN (3mm × 2mm) (Reference LTC DWG # 05-08-1702) 2.00 ±0.10 (2 SIDES) 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 0.38 ± 0.10 BOTTOM VIEW—EXPOSED PAD 0.56 ± 0.05 (2 SIDES) 0.75 ±0.05 R = 0.115 TYP 2.15 ±0.05 (2 SIDES) 3.00 ±0.10 (2 SIDES) PIN 1 BAR TOP MARK (SEE NOTE 6)

0.200 REF

0 – 0.05 (DDB8) DFN 1103 0.25 ± 0.05 2.20 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 0.61 ±0.05 (2 SIDES) 1.15 ±0.05 0.675 ±0.05 2.50 ±0.05 PACKAGE OUTLINE 0.25 ± 0.05

0.50 BSC

© LINEAR TECHNOLOGY CORPORATION 2005 LT 0306 REV A • PRINTED IN THE USA Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com RELATED PARTS PART NUMBER DESCRIPTION COMMENTS Infrastructure LT5511 High Linearity Upconverting Mixer RF Output to 3GHz, 17dBm IIP3, Integrated LO Buffer LT5512 DC-3GHz High Signal Level Downconverting Mixer DC to 3GHz, 17dBm IIP3, Integrated LO Buffer LT5514 Ultralow Distortion, IF Amplifier/ADC Driver 850MHz Bandwidth, 47dBm OIP3 at 100MHz, 10.5dB to 33dB Gain Control Range with Digitally Controlled Gain LT5515 1.5GHz to 2.5GHz Direct Conversion Quadrature 20dBm IIP3, Integrated LO Quadrature Generator Demodulator LT5516 0.8GHz to 1.5GHz Direct Conversion Quadrature 21.5dBm IIP3, Integrated LO Quadrature Generator Demodulator LT5517 40MHz to 900MHz Quadrature Demodulator 21dBm IIP3, Integrated LO Quadrature Generator LT5519 0.7GHz to 1.4GHz High Linearity Upconverting Mixer 17.1dBm IIP3 at 1GHz, Integrated RF Output Transformer with 50 Ω Matching, Single-Ended LO and RF Ports Operation LT5520 1.3GHz to 2.3GHz High Linearity Upconverting Mixer 15.9dBm IIP3 at 1.9GHz, Integrated RF Output Transformer with 50 Ω Matching, Single-Ended LO and RF Ports Operation Upconverting Mixer LO Port Operation LT5522 400MHz to 2.7GHz High Signal Level 4.5V to 5.25V Supply, 25dBm IIP3 at 900MHz, NF = 12.5dB, 50 Ω Single-Ended RF Downconverting Mixer and LO Ports LT5524 Low Power, Low Distortion ADC Driver with Digitally 450MHz Bandwidth, 40dBm OIP3, 4.5dB to 27dB Gain Control Programmable Gain LT5525 High Linearity, Low Power Downconverting Mixer Single-Ended 50 Ω RF and LO Ports, 17.6dBm IIP3 at 1900MHz, ICC = 28mA LT5526 High Linearity, Low Power Downconverting Mixer 3V to 5.3V Supply, 16.5dBm IIP3, 100kHz to 2GHz RF, NF = 11dB, I CC = 28mA, –65dBm LO-RF Leakage LT5527 400MHz to 3.7GHz High Linearity, 23.5dBm IIP3, 12.5dB NF at 1.9GHz, 50 Ω Single-Ended RF and LO Ports Downconverting Mixer LT5528 1.5GHz to 2.4GHz High Linearity Direct I/Q 21.8dBm OIP3 at 2GHz, –159dBm/Hz Noise Floor, 50 Ω Interface at All Ports Modulator RF Power Detectors LT5504 800MHz to 2.7GHz RF Measuring Receiver 80dB Dynamic Range, Temperature Compensated, 2.7V to 5.25V Supply LTC®5505 RF Power Detectors with >40dB Dynamic Range 300MHz to 3GHz, Temperature Compensated, 2.7V to 6V Supply LTC5507 100kHz to 1000MHz RF Power Detector 100kHz to 1GHz, Temperature Compensated, 2.7V to 6V Supply LTC5508 300MHz to 7GHz RF Power Detector 44dB Dynamic Range, Temperature Compensated, SC70 Package LTC5509 300MHz to 3GHz RF Power Detector 36dB Dynamic Range, Low Power Consumption, SC70 Package LTC5530 300MHz to 7GHz Precision RF Power Detector Precision V OUT Offset Control, Shutdown, Adjustable Gain LTC5531 300MHz to 7GHz Precision RF Power Detector Precision V OUT Offset Control, Shutdown, Adjustable Offset LTC5532 300MHz to 7GHz Precision RF Power Detector Precision V OUT Offset Control, Adjustable Gain and Offset LT5534 50MHz to 3GHz RF Power Detector with 60dB ±1dB Output Variation over Temperature, 38ns Response Time Dynamic Range LTC5536 Precision 600MHz to 7GHz RF Detector 25ns Response Time, Comparator Reference Input, Latch Enable Input, with Fast Comparator Output –26dBm to +12dBm Input Range Low Voltage RF Building Block LT5546 500MHz Quadrature Demodulator with VGA and 17MHz Baseband Bandwidth, 40MHz to 500MHz IF, 1.8V to 5.25V Supply, –7dB to 17MHz Baseband Bandwidth 56dB Linear Power Gain Wide Bandwidth ADCs LTC1749 12-Bit, 80Msps 500MHz BW S/H, 71.8dB SNR LTC1750 14-Bit, 80Msps 500MHz BW S/H, 75.5dB SNR