LTC1069-7 Linear Phase 8th Order Lowpass Filter FEATURES ■ ■ ■ ■ ■ ■ ■ 8th Order, Linear Phase Filter in SO-8 Package Raised Cosine Amplitude Response – 43dB Attenuation at 2× fCUTOFF Wideband Noise: 140µVRMS Operates from Single 5V Supply to ±5V Power Supplies Clock-Tunable to 200kHz with ±5V Supplies Clock-Tunable to 120kHz with Single 5V Supply U APPLICATIONS ■ ■ ■ Digital Communication Filter Antialiasing Filter with Linear Phase Smoothing Filters U DESCRIPTION The LTC ®1069-7 is a monolithic, clock-tunable, linear phase, 8th order lowpass filter. The amplitude response of the filter approximates a raised cosine filter with an alpha of one. The gain at the cutoff frequency is – 3dB and the attenuation at twice the cutoff frequency is 43dB. The cutoff frequency of the LTC1069-7 is set by an external clock and is equal to the clock frequency divided by 25. The ratio of the internal sampling frequency to the cutoff frequency is 50:1 that is, the input signal is sampled twice per clock cycle to lower the risk of aliasing. The LTC10697 can be operated from a single 5V supply up to dual ±5V supplies. The gain and phase response of the LTC1069-7 can be used in digital communication systems where pulse shaping and channel bandwidth limiting must be carried out. Any system that requires an analog filter with linear phase and sharper roll off than conventional Bessel filters can use the LTC1069-7. The LTC1069-7 has a wide dynamic range. With ±5V supplies and an input range of 0.1VRMS to 2VRMS, the signal-to-(noise + THD) ratio is ≥ 60dB. The wideband noise of the LTC1069-7 is 140µVRMS. Unlike other LTC1069-X filters, the typical passband gain of the LTC1069-7 is equal to –1V/V. The LTC1069-7 is available in an SO-8 package. Other filter responses with lower power/speed specifications can be obtained. Please contact LTC Marketing. , LTC and LT are registered trademarks of Linear Technology Corporation. U TYPICAL APPLICATION Frequency Response 10 Single 5V Supply, Linear Phase 100kHz Lowpass Filter AGND VOUT 0 –10 VOUT V+ 0.47µF 0.1µF GAIN (dB) 5V V– LTC1069-7 VIN NC NC VIN CLK fCLK = 2.5MHz –20 – 30 – 40 – 50 1069-7 TA01 – 60 –70 10 100 FREQUENCY (kHz) 1000 1069-7 TA02 1 LTC1069-7 W U U W W W Total Supply Voltage (V + to V –) ............................. 12V Power Dissipation............................................. 400mW Operating Temperature Range LTC1069-7C ........................................... 0°C to 70°C LTC1069-7I ....................................... – 40°C to 85°C Storage Temperature ............................ – 65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300°C U ABSOLUTE MAXIMUM RATINGS PACKAGE/ORDER INFORMATION ORDER PART NUMBER TOP VIEW AGND 1 8 VOUT V+ 2 7 V– NC 3 6 NC VIN 4 5 CLK LTC1069-7CS8 LTC1069-7IS8 S8 PART MARKING S8 PACKAGE 8-LEAD PLASTIC SO TJMAX = 125°C, θJA = 110°C/ W 10697 10697I Consult factory for Military grade parts. ELECTRICAL CHARACTERISTICS fCUTOFF is the filter’s cutoff frequency and is equal to fCLK/25. The fCLK signal level is TTL or CMOS (max clock rise or fall time ≤ 1µs), RL = 10k, TA = 25°C, unless otherwise specified. All AC gains are measured relative to the passband gain. PARAMETER CONDITIONS Passband Gain (fIN ≤ 0.2fCUTOFF) VS = ±5V, fCLK = 2.5MHz fTEST = 1kHz, VIN = 1VRMS ● VS = 4.75V, fCLK = 500kHz fTEST = 1kHz, VIN = 0.5VRMS ● VS = ±5V, fCLK = 2.5MHz fTEST = 25kHz, VIN = 1VRMS ● – 0.55 VS = 4.75V, fCLK = 500kHz fTEST = 5kHz, VIN = 0.5VRMS ● – 0.30 VS = ±5V, fCLK = 2.5MHz fTEST = 50kHz, VIN = 1VRMS ● – 1.40 VS = 4.75V, fCLK = 500kHz fTEST = 10kHz, VIN = 0.5VRMS ● – 0.60 VS = ±5V, fCLK = 2.5MHz fTEST = 75kHz, VIN = 1VRMS ● – 2.1 VS = 4.75V, fCLK = 500kHz fTEST = 15kHz, VIN = 0.5VRMS ● – 1.15 VS = ±5V, fCLK = 2.5MHz fTEST = 100kHz, VIN = 1VRMS ● – 4.0 VS = 4.75V, fCLK = 500kHz fTEST = 20kHz, VIN = 0.5VRMS ● – 3.3 VS = ±5V, fCLK = 2.5MHz fTEST = 150kHz, VIN = 1VRMS ● – 19 VS = 4.75V, fCLK = 500kHz fTEST = 30kHz, VIN = 0.5VRMS ● – 20 VS = ±5V, fCLK = 2.5MHz fTEST = 200kHz, VIN = 1VRMS ● – 55 VS = 4.75V, fCLK = 500kHz fTEST = 40kHz, VIN = 0.5VRMS ● – 48 Gain at 0.25fCUTOFF Gain at 0.50fCUTOFF Gain at 0.75fCUTOFF Gain at fCUTOFF Gain at 1.5fCUTOFF Gain at 2.0fCUTOFF 2 MIN TYP MAX UNITS – 0.10 ±0.75 ±0.90 dB dB – 0.10 ±0.75 ±0.90 dB dB – 0.1 dB dB 0.15 dB dB – 0.35 dB dB 0 dB dB – 0.80 dB dB – 0.25 dB dB – 2.7 dB dB – 2.4 dB dB – 14 dB dB – 17 dB dB – 38 dB dB – 39 dB dB – 0.30 – 0.05 – 1.0 – 0.30 – 1.65 – 0.75 – 3.5 – 2.9 – 16.5 – 18.1 – 43 – 41 LTC1069-7 ELECTRICAL CHARACTERISTICS fCUTOFF is the filter’s cutoff frequency and is equal to fCLK/25. The fCLK signal level is TTL or CMOS (max clock rise or fall time ≤ 1µs), RL = 10k, TA = 25°C, unless otherwise specified. All AC gains are measured relative to the passband gain. PARAMETER CONDITIONS MIN TYP MAX UNITS Gain at 5.0fCUTOFF VS = 4.75V, fCLK = 500kHz fTEST = 100kHz, VIN = 0.5VRMS – 70 –59 – 55 dB Gain at fCUTOFF (160kHz) VS = ±5V, fCLK = 4MHz fTEST = 160kHz, VIN = 1VRMS Phase at 0.5fCUTOFF VS = ±5V, fCLK = 2.5MHz fTEST = 50kHz – 35 – 30.5 – 25 Deg Phase at fCUTOFF VS = ±5V, fCLK = 2.5MHz fTEST = 100kHz – 240 – 235 – 230 Deg Passband Phase Deviation from Linear Phase (Note 1) VS = ±5V, fCLK = 500kHz – 3.0 Output DC Offset (Input at GND) VS = ±5V, fCLK = 500kHz VS = 4.75V, fCLK = 400kHz 50 25 – 2.1 Output Voltage Swing VS = ±5V, ISOURCE/ISINK ≤ 1mA, RL = 10k VS = 4.75V, ISOURCE/ISINK ≤ 1mA, RL = 10k Power Supply Current VS = ±5V, fCLK = 500kHz ● ● ±3.5 2.6 ● The ● denotes specifications which apply over the full operating temperature range. Note 1: Phase Deviation = 1/2(Phase at 0Hz – Phase at fCUTOFF) – (Phase at 0Hz – Phase at 0.5fCUTOFF) Phase at 0Hz = 180° (guaranteed by design) Deg mV mV 125 ±4.0 3.6 V VP-P 18 26 29 mA mA 13 15 16.5 mA mA ● VS = 4.75V, fCLK = 400kHz dB Example: An LTC1069-7 has Phase at 0.5fCUTOFF = – 30.5° and Phase at fCUTOFF = – 235°. Passband Phase Deviation from Linear Phase = 1/2[180° – (– 235°)] – [(180° – (– 30.5°)] = – 3° U W TYPICAL PERFORMANCE CHARACTERISTICS Passband Gain vs Frequency Transition Band Gain vs Frequency 10 1.0 VS = ±5V fCLK = 500kHz fC = 20kHz VIN = 2VRMS 0.5 0 0 VS = ±5V fCLK = 500kHz fC = 20kHz VIN = 2VRMS –44 –2.0 –20 –30 –2.5 –3.0 VS = ±5V fCLK = 500kHz fC = 20kHz VIN = 2VRMS –46 GAIN (dB) –1.5 –48 –50 –52 –54 –56 –40 –58 –3.5 –4.0 –42 –10 –1.0 GAIN (dB) GAIN (dB) –0.5 Stopband Gain vs Frequency –40 –50 1 3 5 7 9 11 13 15 17 19 21 FREQUENCY (kHz) LTC1069-7 • TPC01 21 23 25 27 29 31 33 35 37 39 41 FREQUENCY (kHz) LTC1069-7 • TPC02 –60 41 45 49 53 57 61 65 69 73 77 81 FREQUENCY (kHz) LTC1069-7 • TPC03 3 LTC1069-7 U W TYPICAL PERFORMANCE CHARACTERISTICS Passband Gain vs Clock Frequency Gain vs Frequency VS = ±5V fCLK = 250kHz fC = 10kHz VIN = 1VRMS 0 fCLK = 5MHz 0 –3 –20 –30 –0.5 –6 fCLK = 2.5MHz fCLK = 4.5MHz fCLK = 4MHz fCLK = 3.5MHz –9 –12 –40 –15 –60 –18 20 10 FREQUENCY (kHz) 100 –4.0 60 40 80 100 120 140 160 180 200 FREQUENCY (kHz) fCLK = 2MHz fC = 80kHz VIN = 0.5VRMS 0 GAIN (dB) GAIN (dB) GAIN (dB) –30 –6 –9 fCLK = 2.5MHz –12 VS = 5V VS = ±5V –18 20 –60 10 30 50 70 90 110 130 150 170 190 210 FREQUENCY (kHz) VS = 5V fCLK = 2.5MHz fC = 100kHz VIN = 1VRMS –4.0 60 40 10 20 80 100 120 140 160 180 200 FREQUENCY (kHz) 30 40 50 60 70 FREQUENCY (kHz) 2 135 1 90 0 45 –1 0 –45 –90 PHASE 13.5 13.0 GAIN 12.5 –3 –4 –135 –5 –6 –180 –6 –7 –225 –7 –8 –270 10 20 30 40 50 60 70 80 90 100 FREQUENCY (kHz) –8 LTC1069-7 • TPC10 VS = ±5V fCLK = 2.5MHz fC = 100kHz –2 –5 12.0 DELAY 0 90 100 LTC1069-7 • TPC09 11.5 11.0 10 20 30 40 50 60 70 80 90 100 FREQUENCY (kHz) LTC1069-7 • TPC12 DELAY (µs) –3 180 PHASE (DEG) GAIN 80 Passband Gain and Delay vs Frequency GAIN (dB) –1 GAIN (dB) TA = 25°C LTC1069-7 • TPC08 VS = ±5V fCLK = 2.5MHz fC = 100kHz 0 TA = –40°C –2.0 –3.5 Passband Gain and Phase vs Frequency –4 –1.5 –3.0 fCLK = 1.5MHz LTC1069-7 • TPC07 –2 –1.0 –2.5 fCLK = 2MHz –15 TA = 85°C –0.5 fCLK = 3MHz –20 4 0.5 –3 0 160 130 Passband Gain vs Frequency VS = 5V VIN = 1VRMS 0 –10 1 100 70 FREQUENCY (kHz) 1.0 3 2 40 10 LTC1069-7 • TPC06 Passband Gain vs Clock Frequency 10 –50 TA = 25°C LTC1069-7 • TPC05 Gain vs Supply Voltage –40 TA = –40°C –2.0 –3.5 LTC1069-7 • TPC04 0 –1.5 –3.0 VS = ±5V VIN = 2VRMS –50 TA = 85°C –1.0 –2.5 fCLK = 3MHz 1 VS = ±5V fCLK = 4MHz fC = 160kHz VIN = 2VRMS 0.5 0 GAIN (dB) GAIN (dB) –10 Passband Gain vs Frequency 1.0 3 GAIN (dB) 10 LTC1069-7 U W TYPICAL PERFORMANCE CHARACTERISTICS Phase Matching vs Frequency THD + Noise vs Input (VP-P) –40 fCLK = 1MHz fC = 40kHz fIN = 1kHz –45 2.00 1.75 25°C 1.50 1.25 1.00 VS = ±5V fCLK ≤ 2.5MHz PHASE DIFFERENCE BETWEEN ANY TWO UNITS (SAMPLE OF 20 REPRESENTATIVE UNITS) 0.75 0.50 0.25 –50 –50 –55 VS = 5V –60 –65 –55 VS = 5V, VIN = 1VP-P –60 –65 –70 VS = ±5V –70 1 INPUT (VP-P) 0.1 VS = ±5V, VIN = 2VP-P –75 –75 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 FREQUENCY (fCUTOFF/FREQUENCY) fCLK = 2.5MHz fC = 100kHz –45 THD + NOISE (dB) 70°C THD + NOISE (dB) PHASE DIFFERENCE (DEG) 2.25 0 THD + Noise vs Frequency –40 2.50 –80 10 1 10 FREQUENCY (kHz) LTC1609-7 • TPC13 LTC1069-7 • TPC11 Transient Response 100 LTC1069-7 • TPC14 Output Voltage Swing vs Temperature Output Offset vs Clock Frequency –10 4.3 VS = ±5V 0.1ms/DIV fCLK = 500kHz fCUTOFF = 20kHz VIN = 4VP-P SQUARE WAVE AT 1kHz 4.2 –20 VOLTAGE SWING (V) 1V/DIV OUTPUT OFFSET (mV) –15 VS = 5V –25 –30 –35 VS = ±5V –40 VS = 5V (AGND AT 2.5V) fCLK = 500kHz fCUTOFF = 20kHz RL = 10k ISOURCE/ISINK ≤ 1mA 4.1 1.2 1.1 LTC1069-7 • TPC15 –45 –50 0.25 1.25 3.25 4.25 2.25 CLOCK FREQUENCY (MHz) 1.0 –40 –20 5.25 40 20 0 60 TEMPERATURE (°C) LTC1069-7 • TPC16 Output Voltage Swing vs Temperature Supply Current vs Supply Voltage Supply Current vs Clock Frequency 22 fCLK = 10Hz VS = ±5V fCLK = 2.5MHz fCUTOFF = 100kHz RL = 10k ISOURCE/ISINK = 1mA SUPPLY CURRENT (mA) VOLTAGE SWING (V) 4.1 21 25°C 20 85°C SUPPLY CURRENT (mA) 25 –4.5 100 LTC1069-7 • TPC17 4.2 4.0 80 20 –40°C 15 10 –4.6 5 –4.7 –40 –20 0 19 17 16 15 14 13 12 11 40 20 0 60 TEMPERATURE (°C) 80 100 LTC1069-7 • TPC18 VS = ±5V 18 0 1 4 2 3 SUPPLY VOLTAGE (±V) 5 6 LTC1069-7 • TPC19 10 0.25 VS = 5V 1.25 2.25 3.25 4.25 CLOCK FREQUENCY (MHz) 5.25 LTC1263 • TPC20 5 LTC1069-7 U U U PIN FUNCTIONS AGND (Pin 1): Analog Ground. The quality of the analog signal ground can affect the filter performance. For either single or dual supply operation, an analog ground plane surrounding the package is recommended. The analog ground plane should be connected to any digital ground at a single point. For dual supply operation, Pin 1 should be connected to the analog ground plane. For single supply operation, Pin 1 should be bypassed to the analog ground plane with a capacitor 0.47µF or larger. An internal resistive divider biases Pin 1 to half the total power supply. Pin 1 should be buffered if used to bias other ICs. Figure 1 shows the connections for single supply operation. V+, V – (Pins 2, 7): Power Supplies. The V+ (Pin 2) and V – (Pin 7) should be bypassed with a 0.1µF capacitor to an adequate analog ground. The filter’s power supplies should be isolated from other digital or high voltage analog supplies. A low noise linear supply is recommended. Using switching power supplies will lower the signal-tonoise ratio of the filter. Unlike previous monolithic filters, the power supplies can be applied in any order, that is, the positive supply can be applied before the negative supply and vice versa. Figure 2 shows the connections for dual supply operation. NC (Pins 3, 6): No Connection. Pins 3 and 6 are not connected to any internal circuitry; they should be tied to ground. VIN (Pin 4): Filter Input. The filter input pin is internally connected to the inverting inputs of two op amps through V+ 0.1µF 2 3 4 VIN AGND V+ VOUT LTC1069-7 V– NC NC VIN CLK DIGITAL GROUND PLANE 8 VOUT 7 POWER SUPPLY HIGH LEVEL LOW LEVEL Dual Supply = ±5V 1.5V 0.5V Single Supply = 10V 6.5V 5.5V Single Supply = 5V 1.5V 0.5V VOUT (Pin 8): Filter Output. Pin 8 is the output of the filter, and it can source 23mA or sink 16mA. The total harmonic distortion of the filter will degrade when driving coaxial cables or loads less than 20k without an output buffer. 2 V+ 0.1µF 6 5 1k CLOCK SOURCE LTC1069-7 • F01 Figure 1. Connections for Single Supply Operation 6 Table 1. Clock Source High and Low Thresholds 1 1 STAR SYSTEM GROUND CLK (Pin 5): Clock Input. Any TTL or CMOS clock source with a square wave output and 50% duty cycle (±10%) is an adequate clock source for the device. The power supply for the clock source should not necessarily be the filter’s power supply. The analog ground of the filter should only be connected to the clock’s ground at a single point. Table 1 shows the clock’s low and high level threshold value for a dual or single supply operation. A pulse generator can be used as a clock source provided the high level on-time is greater than 0.42µs (VS = ± 5V). Sine waves less than 100kHz are not recommended for clock sources because excessive slow clock rise or fall times generate internal clock jitter. The maximum clock rise or fall time is 1µs. The clock signal should be routed from the right side of the IC package to avoid coupling into any input or output analog signal path. A 1k resistor between the clock source and the clock input (Pin 5) will slow down the rise and fall times of the clock to further reduce charge coupling, Figure 1. ANALOG GROUND PLANE ANALOG GROUND PLANE 0.47µF a 36k resistor for each op amp. This parallel combination creates an 18k input impedance. STAR SYSTEM GROUND AGND V+ VOUT V– 8 VOUT 7 LTC1069-7 3 6 NC NC 4 5 VIN CLK VIN DIGITAL GROUND PLANE V– 0.1µF 1k CLOCK SOURCE LTC1069 F02 Figure 2. Connections for Dual Supply Operation LTC1069-7 U W U U APPLICATIONS INFORMATION Temperature Behavior The power supply current of the LTC1069-7 has a positive temperature coefficient. The GBW product of its internal op amps is nearly constant and the speed of the device does not degrade at high temperatures. the clock frequency and depends slightly on the power supply voltage (see Table 3). The clock feedthrough specifications are not part of the wideband noise. Table 3. Wideband Noise VS Clock Feedthrough The clock feedthrough is defined as the RMS value of the clock frequency and its harmonics that are present at the filter’s output (Pin 8). The clock feedthrough is tested with the input (Pin 4) shorted to the AGND pin and depends on PC board layout and on the value of the power supplies. With proper layout techniques the values of the clock feedthrough are shown on Table 2. Table 2. Clock Feedthrough VS CLOCK FEEDTHROUGH 5V 400µVRMS ±5V 850µVRMS Any parasitic switching transients during the rising and falling edges of the incoming clock are not part of the clock feedthrough specifications. Switching transients have frequency contents much higher than the applied clock; their amplitude strongly depends on scope probing techniques as well as grounding and power supply bypassing. The clock feedthrough can be reduced by adding a single RC lowpass filter at the output (Pin 8) of the LTC1069-7. WIDEBAND NOISE 4.75V 125µVRMS ± 5V 140µVRMS Aliasing Aliasing is an inherent phenomenon of sampled data systems and it occurs for input frequencies approaching the sampling frequency. The internal sampling frequency of the LTC1069-7 is 50 times its fCUTOFF frequency. For instance if a 48kHz, 100mVRMS signal is applied at the input of an LTC1069-7 operating with a 50% duty cycle 25kHz clock, a 2kHz, 741µVRMS alias signal will appear at the filter output. Table 4 shows details. Table 4. Aliasing INPUT FREQUENCY VIN = 1VRMS OUTPUT LEVEL Relative to Input OUTPUT FREQUENCY Aliased Frequency fCLK /fC = 25:1, fCUTOFF = 1kHz 40kHz (or 60kHz) –59.9dB 10kHz 47kHz (or 53kHz) –54.2dB 3kHz 48kHz (or 52kHz) –42.6dB 2kHz 48.5kHz (or 51.5kHz) –18.3dB 1.5kHz 49kHz (or 52kHz) –2.9dB 1.0kHz 49.5kHz (or 50.5kHz) –0.65dB 0.5kHz Wideband Noise Speed Limitations The wideband noise of the filter is the total RMS value of the device’s noise spectral density and determines the operating signal-to-noise ratio. Most of the wideband noise frequency contents lie within the filter passband. The wideband noise cannot be reduced by adding post filtering. The total wideband noise is nearly independent of To avoid op amp slew rate limiting, the signal amplitude should be kept below a specified level as shown in Table 5. Table 5. Maximum VIN vs VS and Clock VS MAXIMUM CLOCK MAXIMUM VIN 5V ≥ 2.5MHz 340mVRMS (fIN ≥ 200kHz) ±5V ≥ 4.5MHz 1.2VRMS (fIN ≥ 400kHz) 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. 7 LTC1069-7 U TYPICAL APPLICATION Clock Tunable, Noninverting, Linear Phase 8th Order Filter to 200kHz fCUTOFF 51pF 10k 5V 0.1µF 1µF AGND 10k VOUT –5V 5V V+ 0.1µF LT ®1354 V– VOUT + 0.1µF LTC1069-7 NC – NC 0.1µF –5V VIN VIN CLK fCLK ≤ 5MHz 1069-7 TA03 U PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. S8 Package 8-Lead Plastic Small Outline (Narrow 0.150) (LTC DWG # 05-08-1610) 0.189 – 0.197* (4.801 – 5.004) 8 0.010 – 0.020 × 45° (0.254 – 0.508) 0.008 – 0.010 (0.203 – 0.254) 0.053 – 0.069 (1.346 – 1.752) 0°– 8° TYP 0.016 – 0.050 0.406 – 1.270 0.014 – 0.019 (0.355 – 0.483) *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 7 6 5 0.004 – 0.010 0.228 – 0.244 (0.101 – 0.254) (5.791 – 6.197) 0.050 (1.270) TYP 0.150 – 0.157** (3.810 – 3.988) 1 2 3 4 SO8 0996 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC1064-3 Linear Phase, Bessel 8th Order Filter fCLK/fC = 75/1 or 150/1, Very Low Noise LTC1064-7 Linear Phase, 8th Order Lowpass Filter fCLK/fC = 50/1 or 100/1, fC(MAX) = 100kHz LTC1164-7 Low Power, Linear Phase Lowpass Filter fCLK/fC = 50/1 or 100/1, IS = 2.5mA, VS = 5V LTC1264-7 Linear Phase 8th Order Lowpass Filter fCLK/fC = 25/1 or 50/1, fC(MAX) = 200kHz 8 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 ● (408) 432-1900 FAX: (408) 434-0507● TELEX: 499-3977 ● www.linear-tech.com 10697f LT/TP 0697 7K • PRINTED IN USA LINEAR TECHNOLOGY CORPORATION 1996