156531

LTC1565-31_1 LINER

Document overview

• Manufacturer or author: Provided By www.digicamel.com(FREE DATASHEET DOWNLOAD SITE)
• PDF pages: 12

Technical content

650kHz Continuous Time, Linear Phase Lowpass Filter The LTC 1565-31 is a 7th order, continuous time, linear phase lowpass filter. The selectivity of the LTC1565-31, combined with its linear phase and dynamic range, make it suitable for filtering in data communications or data acqui- sition systems. The filter attenuation is 36dB at 2· f CUTOFF and at least 72dB for frequencies above 3· fCUTOFF. Unlike comparable LC filters, the LTC1565-31 achieves this selec- tivity with a linear phase response in the passband. With 5% accuracy of the cutoff frequency, the LTC1565-31 can be used in applications requiring pairs of matched filters, such as transceiver I and Q channels. Furthermore, the differential inputs and outputs provide a simple interface for these wireless systems. With a single 5V supply and a 2V P-P input, the LTC1565-31 features an impressive spurious free dynamic range of 75dB. The maximum signal-to-noise ratio is 78dB and it is achieved with a 2.5V P-P input signal. The LTC1565-31 features a shutdown mode where power supply current is typically less than 10mA. For W-CDMA, 3G, CDMA 2000 and other cellular and noncellular cutoff frequencies or single-ended I/O, please contact LTC Marketing for additional information. n CDMA Base Stations n Data Communications n Antialiasing Filters n Smoothing or Reconstruction Filters n Matched Filter Pairs n Replacement for LC Filters n 7th Order, 650kHz Linear Phase Filter in an SO-8 n Differential Inputs and Outputs n Operates on a Single 5V or a –5V Supply n Low Offset: 5mV Typical n 75dB THD and SNR n 78dB SNR n Shutdown Mode n Requires No External Components n Requires No External Clock Signal Single 5V Supply, Differential 650kHz Lowpass Filter +IN –IN GND +OUT –OUT V SHDN LTC1565-31 0.1µF 0.1µF 15645-31 TA01 VOUT+ VOUT– VIN+ VIN– , LTC and LT are registered trademarks of Linear Technology Corporation. FREQUENCY (Hz) 104 GAIN (dB) DELAY (µs) 105 106 107

1565 G01

–10 –20 –30 –40 –50 –60 –70 –80 –90 –100 2.0 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1.0 0.9 1.9 GAIN DELAY Frequency Response FEATURES DESCRIPTIO U APPLICATIO SU TYPICAL APPLICATIO U

PARAMETER CONDITIONS MIN TYP MAX UNITS Operating Supply Voltage 4.75 11 V Filter Gain V IN = 1VP-P, fIN = 25kHz l –0.3 0 0.3 dB fIN = 200kHz (Gain Relative to 25kHz) l –0.2 0 0.1 dB fIN = 300kHz (Gain Relative to 25kHz) l –0.7 –0.4 –0.1 dB fIN = 500kHz (Gain Relative to 25kHz) l –2.2 –1.6 – 0.95 dB fIN = 650kHz (Gain Relative to 25kHz) l –4 –3 –2 dB fIN = 900kHz (Gain Relative to 25kHz) l –11 –7 dB fIN = 1.3MHz (Gain Relative to 25kHz) l –36 –31 dB fIN = 2.3MHz (Gain Relative to 25kHz) –72 dB Filter Phase V IN = 1VP-P, fIN = 25kHz –13 Deg fIN = 200kHz –101 Deg fIN = 300kHz l –162 –150 –138 Deg fIN = 500kHz 113 Deg fIN = 600kHz l 34 60 85 Deg fIN = 650kHz 36 Deg fIN = 900kHz – 92 Deg Phase Linearity Ratio of 600kHz Phase/300kHz Phase l 1.95 2 2.03 Wideband Noise Noise BW = DC to 2 • f CUTOFF 118 mVRMS THD f IN = 100kHz, 1VP-P (Note 2) 86 dB Filter Differential DC Swing Maximum Difference Between Pins 7 and 8 VS = 5V l –1.4 –1.7 –1.9 V P Input Bias Current 0.1 0.3 0.6 mA Input Offset Current –10 nA Input Resistance Common Mode, V IN = 2.5V 75 M W Differential 145 M W Input Capacitance 3p F Output DC Offset (Note 3) V S = 5V –5 – 12 mV VS = –5V (Note 5) –5 – 12 mV Operating Temperature Range (Note 1) ORDER PART NUMBER LTC1565-31CS8 LTC1565-31IS8 TJMAX = 150°C, qJA = 80°C/ W (NOTE 4) Consult factory for Military grade parts. ABSOLUTE MAXIMUM RATINGSW WW U PACKAGE/ORDER INFORMATIONW UU

ELECTRICAL CHARACTERISTICS

+OUT –OUT V SHDN +IN –IN GND S8 PACKAGE 8-LEAD PLASTIC SO S8 PART MARKING 156531 56531I The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VS = 5V, RLOAD = 10k from each output to AC ground, and Pin 5 open unless otherwise specified.

Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: Input and output voltages expressed as peak-to-peak numbers are assumed to be fully differential. Note 3: Output DC offset is measured between Pin 8 and Pin 7 with Pin 1 and Pin 2 connected to Pin 3. PARAMETER CONDITIONS MIN TYP MAX UNITS Output DC Offset Drift V S = 5V –400 mV/°C VS = –5V –400 mV/°C Ground Voltage (Pin 3) in V S = 5V l 2.49 2.51 2.52 V Single Supply Applications SHDN Pin Logic Thresholds V S = 5V, Minimum Logical “1” l 4.2 V VS = 5V, Maximum Logical “0” l 3.3 V VS = –5V, Minimum Logical “1” l 2.9 V VS = –5V, Maximum Logical “0” l 2.4 V SHDN Pin Pull-Up Current V S = 5V 5 mA VS = –5V 9 mA Power Supply Current V S = 5V l 24 31 mA VS = –5V l 25 33 mA Power Supply Current in Shutdown Mode Shutdown. Includes SHDN Pull-Up Current VS = 5V l 81 6 mA VS = –5V l 20 40 mA Note 4: Thermal resistance varies depending upon the amount of PC board metal attached to the device. qJA is specified for a 3.8 square inch test board covered with 2 oz copper on both sides. Note 5: Output DC offset measurements are performed by automatic test equipment approximately 0.5 seconds after application of power. ELECTRICAL CHARACTERISTICSThe l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VS = 5V, RLOAD = 10k from each output to AC ground, and Pin 5 open unless otherwise specified. TYPICAL PERFOR A CE CHARACTERISTICS UW Frequency Response FREQUENCY (Hz) 104 GAIN (dB) DELAY (µs) 105 106 107 –10 –20 –30 –40 –50 –60 –70 –80 –90 –100 2.0 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1.0 0.9 1.9 GAIN DELAY FREQUENCY (Hz) 25k –4.5 GAIN (dB) DELAY (µs) –3.5 –2.5 –1.5 –0.5 100k 1M

1565 G02

0.5 GAIN

–4.0 –3.0 –2.0 DELAY –1.0 1.0 1.2 1.4 1.6 1.8 2.0 1.1 1.3 1.5 1.7 1.9 5V –5V TA = 25°C Passband Gain and Delay vs Frequency

TYPICAL PERFOR A CE CHARACTERISTICS UW Passband Gain vs Frequency Over Temperature FREQUENCY (Hz) 25k –0.5 GAIN (dB) –0.3 –0.1 0.1 0.3 100k 400k

1565 G03

0.5 –0.4 –0.2 0.2 –40°C 0.4 VS = 5V 85°C 25°C FREQUENCY (MHz) 1.5 GAIN (dB) –60 –50 –40 2.7

1565 G04

–70 –80 –90 1.8 2.1 2.4 3.0 VS = –5V VS = 5V FREQUENCY (MHz) 1.5 GAIN (dB) –60 –50 –40 2.7 –70 –80 –90 1.8 2.1 2.4 3.0 –40°C 85°C 25°C VS = 5V Stopband Gain vs Frequency Stopband Gain vs Frequency Over Temperature Common Mode Rejection Ratio FREQUENCY (Hz) CMRR (dB) 110 100 103 104 105 106 107

1565 G06

VIN = 1VP-P VS = 5V TA = 25°C Power Supply Rejection Ratio FREQUENCY (Hz) PSRR (dB) 103 104 105 106 107

1565 G07

VIN = 200mVP-P VS = 5V TA = 25°C Supply Current vs Temperature TEMPERATURE (°C) –50 SUPPLY CURRENT (mA) 10 50

1565 G08

–30 –10 30 70 90 VS = 5V VS = –5V PIN FUNCTIONSUU U +IN, –IN (Pins 1, 2): Input Pins. Signals can be applied to either or both input pins. The typical DC gain from differ- ential inputs (Pin 1 to Pin 2) to the differential outputs (Pin 8 to Pin 7) is 1.0V/V. The input range is described in the Applications Information section. GND (Pin 3): Ground. The ground pin is the reference voltage for the filter and is internally biased to one-half the total power supply voltage of the filter, maximizing the dynamic range of the filter. For single supply operation, the ground pin should be bypassed with a quality 0.1 mF ceramic capacitor to Pin 4. For dual supply operation, connect Pin 3 to a high quality DC ground. A ground plane should be used. A poor ground will increase noise and distortion. The impedance seen at Pin 3 is 2.5kW in normal mode. In shutdown, the pin is internally biased to the same levels as normal mode. The impedance in shutdown mode is typically 500k W but varies with supply voltage and temperature.

V–, V + (Pins 4, 6): Power Supply Pins. For a single 5V supply (Pin 4 grounded), a quality 0.1mF ceramic bypass capacitor is required from the positive supply pin (Pin 6) to the negative supply pin (Pin 4). The bypass should be as close as possible to the IC. For dual supply applications (Pin 3 is grounded), bypass Pin 6 to Pin 3 and Pin 4 to Pin 3 with a quality 0.1mF ceramic capacitor. The maximum voltage difference between the ground pin (Pin 3) and the positive supply pin (Pin 6) should not exceed 5.5V. BLOCK DIAGRA W R INPUT BUFFERS WITH COMMON MODE TRANSLATION CIRCUIT R ~1M SHUTDOWN SWITCH +IN –IN 7th ORDER LINEAR PHASE FILTER NETWORK GND ~1M SHUTDOWN SWITCH 3 6 4 5 8 +OUT 7 –OUT OUTPUT BUFFER OUTPUT BUFFER SHUTDOWN SHDN 1565-31 BD 4µA SHDN (Pin 5): Shutdown. When the Pin 5 voltage is low, the LTC1565-31 goes into the current saving shutdown mode. Pin 5 has a 4mA pull-up current. Leaving Pin 5 open will place the LTC1565-31 in its normal operating mode. – OUT, + OUT (Pins 7, 8): Output Pins. Pins 7 and 8 are the filter differential output. Each pin can drive 1kW or 300pF loads. The common mode voltage at the output pins is the same as the voltage at Pin 3.

is 2V and – 0.5V respectively. input to Pin 3 or a common mode reference. Figure 5. Dynamic Range Diff-In, Diff-Out Figure 6. THD vs VIN for a Common Mode differentially and the output is observed differentially. single-ended outputs will decrease the performance. mode input voltage that is 0.5V below mid supply.

0 VIN = 2VP-P 100kHz

Figure 7. THD vs Common Mode Output Voltage Figure 8. THD vs Common Mode Output Voltage

in wideband noise with supply voltage. Table 1. Wideband Noise vs Bandwidth, Single 5V Supply Table 2. Wideband Noise vs Supply Voltage, fCUTOFF = 650kHz

Single-Ended Input/Output Dual Supply Filter 0.1µF 0.1µF 0.1µF 5V R2 2.49k +IN –IN GND 1VIN 4–5V +OUT –OUT LTC1565-31 SHDN LT1809 0.1µF 0.1µF 1565-31 TA09 VOUT2.49k –5V 4.99k 4.99k NOTE: FOR SINGLE 5V SUPPLY CONNECTION, PIN 4 (LTC1565-31) AND PIN 4 (LT1809) SHOULD BE GROUNDED AND RESISTOR R2 SHOULD BE DC BIASED AT APPROXIMATELY 2.5V (SEE TEST CIRCUIT FOR SINGLE SUPPLY OPERATION) A Fully Differential Filter with Adjustable Output Common Mode Voltage 0.1µF 0.1µF –3V ≤ VOUT(CM) ≤ 3V *–3.4V ≤ VIN(CM) ≤ 2.5V VIN(CM) CAN BE EQUAL OR DIFFERENT FROM VOUT(CM) NOTE: FOR SINGLE 5V SUPPLY OPERATION, PIN 4 (LTC1565-31), PIN 4 (LT1812) AND RESISTOR R2 SHOULD BE GROUNDED +IN –IN GND V 1VIN+* VIN–* VOUT+ VOUT–2 4–5V +OUT –OUT LTC1565-31 SHDN LT1812 0.1µF 0.1µF 100pF0.1µF 1565-31 TA10 –5V V– + (V+ – V–)R2 R1 + R2VOUT(CM) =

+IN –IN GND +OUT –OUT V SHDN LTC1565-31 0.1µF 0.1µF 15645-31 TA06 VOUT+ 4.99k 1Msps DATA VOUT– 4.99k 10k 4.99k Simple Pulse Shaping Circuit for Single 5V Operation, 2Mbps (1Msps) 4 Level Data 500mV/DIV 200ns/DIV 1565-31 TA07 +IN –IN GND +OUT –OUT V SHDN LTC1565-31 0.1µF 0.1µF 15645-31 TA04 VOUT+ 4.99k 1.25Mbps DATA VOUT– 4.99k 4.99k Simple Pulse Shaping Circuit for Single 5V Operation, 1.25Mbps 2 Level Data 500mV/DIV 250ns/DIV 1565-31 TA05

Dimensions in inches (millimeters) unless otherwise noted.PACKAGE DESCRIPTIONU 8-Lead Plastic Small Outline (Narrow 0.150) (LTC DWG # 05-08-1610) 0.016 – 0.050 (0.406 – 1.270) 0.010 – 0.020 0°– 8° TYP 0.008 – 0.010 (0.203 – 0.254) SO8 1298 0.053 – 0.069 (1.346 – 1.752) 0.014 – 0.019 (0.355 – 0.483) TYP 0.004 – 0.010 (0.101 – 0.254) 0.050 (1.270) BSC 1 2 3 4 0.150 – 0.157** (3.810 – 3.988) 8 7 6 5 0.189 – 0.197* (4.801 – 5.004) 0.228 – 0.244 (5.791 – 6.197) DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE 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. TYPICAL APPLICATIO SU ADC I Q LTC1565-31 LPF ADC 1565-31 TA03 LTC1565-31 LPF RF/IF SECTION DSP90° 90° LO Narrowband Cellular Base Station Receiver

ª LINEAR TECHNOLOGY CORPORATION 2000 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 l FAX: (408) 434-0507 l www.linear-tech.com 156531f LT/LCG 1000 4K • PRINTED IN USA PART NUMBER DESCRIPTION COMMENTS LTC1560-1 1MHz/500kHz Continuous Time, Low Noise, Lowpass Elliptic Filter f CUTOFF = 500kHz or 1MHz LTC1562/LTC1562-2 Universal 8th Order Active RC Filters f CUTOFF(MAX) = 150kHz (LTC1562), fCUTOFF(MAX) = 300kHz (LTC1562-2) LTC1563-2/LTC1563-3 4th Order Active RC Lowpass Filters f CUTOFF(MAX) = 256kHz LTC1569-6/LTC1569-7 Self Clocked, 10th Order Linear Phase Lowpass Filters f CLK/fCUTOFF = 64/1, fCUTOFF(MAX) = 75kHz (LTC1569-6) fCLK/fCUTOFF = 32/1, fCUTOFF(MAX) = 300kHz (LTC1569-7) RELATED PARTS TYPICAL APPLICATIO U Selective 620kHz CDMA Filter +IN –IN GND +OUT –OUT V SHDN LTC1565-31 0.1µF 180pF FGND 0.1µF 18pF 0.1µF 15645-31 TA11 VOUT1 VOUT2 LT1813 18pF 1000pF 150pF R11 R12 1.24k 1.24k 562Ω 562Ω 562Ω VIN1 VIN2 562Ω R10 1.13k 1.13k FREQUENCY (Hz) 100k GAIN (dB) –42 –30 –18

1565 TA12

–48 –36 –24 –12 Frequency Response