LTC Low Power, 8th Order Progressive Elliptic, Lowpass Filter DESCRIPTION FEATURES APPLICATIONS TYPICAL APPLICATION

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1 FEATURES n th Order Eiptic Fiter in SO- Package n Operates from Singe.V to ±V Power Suppies n at.f CUTOFF n at.f CUTOFF n at f CUTOFF n Wide Dynamic Range n μv RMS Wideband Noise n.ma Suppy Current with ±V Suppies n.ma Suppy Current with Singe V Suppy n ma Suppy Current with Singe.V Suppy APPLICATIONS n Teecommunication Fiters n Antiaiasing Fiters L, LT, LTC and LTM are registered trademarks of Linear Technoogy Corporation. A other trademarks are the property of their respective owners. LTC9- Low Power, th Order Progressive Eiptic, Lowpass Fiter DESCRIPTION The LTC 9- is a monoithic th order owpass fiter featuring cock-tunabe cutoff frequency and.ma power suppy current with a singe V suppy. An additiona feature of the LTC9- is operation with a singe.v suppy. The cutoff frequency (f CUTOFF ) of the LTC9- is equa to the cock frequency divided by. The gain at f CUTOFF is. and the typica passband rippe is ±. up to.9f CUTOFF. The stopband attenuation of the LTC9- features a progressive eiptic response reaching attenuation at.f CUTOFF, attenuation at.f CUTOFF and attenuation at f CUTOFF. With ±V suppies, the LTC9- cutoff frequency can be cock-tuned up to khz; with a singe V suppy, the maximum cutoff frequency is khz. The ow power feature of the LTC9- does not penaize the device s dynamic range. With ±V suppies and an input range of.v RMS to.v RMS, the signa-to-(noise + THD) ratio is. The wideband noise of the LTC9- is μv RMS. Other fiter responses with ower power or higher speed can be obtained. Pease contact LTC marketing for detais. The LTC9- is avaiabe in -pin PDIP and -pin SO packages. TYPICAL APPLICATION Singe.V Suppy khz Eiptic Lowpass Fiter +.μf.v.μf AGND V + V LTC9- f khz 9- TA GAIN () Frequency Response... 9 TA 9fa

2 LTC9- ABSOLUTE MAXIMUM RATINGS (Note ) Tota Suppy Votage (V + to V )...V Maximum Votage at Any Pin...(V.V) V (V+ +.V) Operating Temperature Range LTC9C-... C to C LTC9I-... C to C Storage Temperature Range... C to C Lead Temperature (Sodering, sec)... C PIN CONFIGURATION TOP VIEW TOP VIEW AGND V + V AGND V + V NC NC NC NC N PACKAGE -LEAD PLASTIC DIP T JMAX = C, θ JA = C/W S PACKAGE -LEAD PLASTIC SO T JMAX = C, θ JA = C/W ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION SPECIFIED TEMPERATURE RANGE LTC9-CN#PBF LTC9- -Lead Pastic DIP C to C LTC9-IN#PBF LTC9- -Lead Pastic DIP C to C LTC9-CS#PBF LTC9-CS#TRPBF 9 -Lead Pastic SO C to C LTC9-IS#PBF LTC9-IS#TRPBF 9I -Lead Pastic SO C to C Consut LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a abe on the shipping container. Consut LTC Marketing for information on non-standard ead based fi nish parts. For more information on ead free part marking, go to: For more information on tape and ree specifi cations, go to: ELECTRICAL CHARACTERISTICS The denotes the specifi cations which appy over the fu operating temperature range, otherwise specifi cations are at T A = C. f CUTOFF is the fi ter s cutoff frequency and is equa to f /. The f signa eve is TTL or CMOS (cock rise or fa time μs), V S =.V to ±V, R L = k, uness otherwise noted. A AC gains are measured reative to the passband gain. PARAMETER CONDITIONS MIN TYP MAX UNITS Passband Gain (f IN.f CUTOFF ), f = khz... f TEST =.khz, = V RMS.. V S =.V, f = khz f TEST =.khz, =.V RMS fa

3 ELECTRICAL CHARACTERISTICS Note : Stresses beyond those isted under Absoute Maximum Ratings may cause permanent damage to the device. Exposure to any Absoute Maximum Rating condition for extended periods may affect device reiabiity and ifetime. LTC9- The denotes the specifi cations which appy over the fu operating temperature range, otherwise specifi cations are at T A = C. f CUTOFF is the fi ter s cutoff frequency and is equa to f /. The f signa eve is TTL or CMOS (cock rise or fa time μs), V S =.V to ±V, R L = k, uness otherwise noted. A AC gains are measured reative to the passband gain. PARAMETER CONDITIONS MIN TYP MAX UNITS Gain at.f CUTOFF, f = khz... f TEST =.khz, = V RMS.. V S =.V, f = khz f TEST = khz, =.V RMS Gain at.f CUTOFF, f = khz f TEST =.khz, = V RMS V S =.V, f = khz f TEST =.khz, =.V RMS Gain at.9f CUTOFF, f = khz f TEST =.khz, = V RMS V S =.V, f = khz f TEST =.khz, =.V RMS Gain at.9f CUTOFF, f = khz f TEST =.khz, = V RMS V S =.V, f = khz f TEST =.9kHz, =.V RMS Gain at f CUTOFF, f = khz f TEST =.khz, = V RMS V S =.V, f = khz f TEST =.khz, =.V RMS Gain at.f CUTOFF, f = khz f TEST =.khz, = V RMS V S =.V, f = khz f TEST =.khz, =.V RMS Gain at.f CUTOFF, f = khz f TEST =.khz, = V RMS V S =.V, f = khz f TEST = khz, =.V RMS Output DC Offset (Input at AGND), f = khz V S =.V, f = khz V S =.V, f = khz Output Votage Swing V S =.V V S =.V Power Suppy Current, f = khz V S =.V, f = khz V S =.V, f = khz Maximum Cock Frequency V S =.V V S =.V Input Frequency Range f / MHz Input Resistance kω Operating Power Suppy Votage ±. ±. V... ±. ±. ± mv mv mv V V V ma ma ma MHz MHz MHz 9fa

4 LTC9- TYPICAL PERFORMANCE CHARACTERISTICS GAIN () Passband Gain vs Frequency f = khz f C = khz = V RMS G GAIN (DB) Transition Band Gain vs Frequency f = khz f C = khz = V RMS G GAIN () Stopband Gain vs Frequency f = khz f C = khz = V RMS G.. Passband Gain vs Cock Frequency, V S = Singe.V V S = SINGLE.V =.V RMS.. Passband Gain vs Cock Frequency, V S = Singe V V S = SINGLE V =.V RMS.. Passband Gain vs Cock Frequency, = V RMS GAIN ()..... f = khz f C = khz f = khz f C =.khz GAIN ()..... f = khz f C =.khz f = khz f C = khz f = MHz f C = khz GAIN ()..... f = khz f C = khz f =.MHz f C = khz f = MHz f C = khz G G. 9 9 G GAIN () Gain vs Suppy Votage f = khz =.V RMS V S =.V V S = V G PHASE (DEG) 9 Phase and Group Deay vs Frequency PHASE GROUP DELAY V S = SINGLE V f = khz f C = khz 9 G GROUP DELAY (ms) V/DIV Transient Response.ms/DIV f = MHz f IN = Hz V P-P SQUARE WAVE 9 G9 9fa

5 TYPICAL PERFORMANCE CHARACTERISTICS LTC9- THD + NOISE () Dynamic Range THD + Noise vs (V RMS ) THD + Noise vs Frequency THD + Noise vs Frequency f = khz f IN = khz V S =.V V S = V V S = ±V INPUT VOLTAGE (V RMS ) 9 G THD + NOISE () f = khz = mv RMS V S =.V V S = V INPUT 9 G THD + NOISE () 9 f = khz V S =.V =.V RMS V S = V = V RMS = V RMS INPUT 9 G Suppy Current vs Suppy Votage f = Hz. Suppy Current vs Cock Frequency Output Votage Swing vs Temperature SUPPLY CURRENT (ma) C C C SUPPLY CURRENT (ma)..... V S = V V S =.V OUTPUT VOLTAGE SWING (V) V S = ±.V V S = ±.V V S = ±.V V S = ±.V TOTAL SUPPLY VOLTAGE (±V) 9 G CLOCK FREQUENCY (MHz) 9 G AMBIENT TEMPERATURE ( C) 9 G 9fa

6 LTC9- PIN FUNCTIONS AGND (Pin ): Anaog Ground. The quaity of the anaog signa ground can affect the fiter performance. For either singe or dua suppy operation, an anaog ground pane surrounding the package is recommended. The anaog ground pane shoud be connected to any digita ground at a singe point. For dua suppy operation Pin shoud be connected to the anaog ground pane. For singe suppy operation Pin shoud be bypassed to the anaog ground pane with a.μf or arger capacitor. An interna resistive divider biases Pin to / the tota power suppy. Pin shoud be buffered if used to bias other ICs. Figure shows the connections for singe suppy operation. V +, V (Pins, ): Power Suppy Pins. The V + (Pin ) and the V (Pin ) shoud be bypassed with a.μf capacitor to an adequate anaog ground. The fiter s power suppies shoud be isoated from other digita or high votage anaog suppies. A ow noise inear suppy is recommended. Using switching power suppies wi ower the signa-to-noise ratio of the fiter. Unike previous monoithic fi ters, the power suppies can be appied at any order, that is, the positive suppy can be appied before the negative suppy and vice versa. Figure shows the connection for dua suppy operation. NC (Pins, ): No Connection. Pins and are not connected to any interna circuity; they shoud be preferaby tied to ground. (Pin ): Fiter Input Pin. The fi ter input pin is internay connected to the inverting input of an op amp through a k resistor. (Pin ): Cock Input Pin. Any TTL or CMOS cock source with a square wave output and % duty cyce (±%) is an adequate cock source for the device. The power suppy for the cock source shoud not necessariy be the fiter s power suppy. The anaog ground of the fiter shoud be connected to cock s ground at a singe point ony. Tabe shows the cock s ow and high eve threshod vaue for a dua or a singe suppy operation. A puse generator can be used as a cock source provided the high eve ON time is greater than.μs (). Sine waves ess than khz are not recommended for cock signa because excessive sow cock rise or fa times generate interna cock jitter. The maximum cock rise or fa is μs. The cock signa shoud be routed from the right side of the IC package to avoid couping into any input or output anaog signa path. A k resistor between the cock source and the cock input pin () wi sow down the rise and fa times of the cock to further reduce charge couping, Figure. Tabe. Cock Source High and Low Threshods POWER SUPPLY HIGH LEVEL LOW LEVEL Dua Suppy = ±V.V.V Singe Suppy = V.V.V Singe Suppy = V.V.V Singe Suppy =.V.V.V (Pin ): Fiter Output Pin. Pin is the output of the fiter and it can source or sink ma. Driving coaxia cabes or resistive oads ess than k wi degrade the tota harmonic distortion of the fiter. When evauating the device s dynamic range, a buffer is required to isoate the fi ter s output from coax cabes and instruments..μf V +.μf AGND V + V LTC9- AGND V + V + V V.μF LTC9-.μF ANALOG GROUND PLANE ANALOG GROUND PLANE STAR SYSTEM GROUND DIGITAL GROUND PLANE k CLOCK SOURCE STAR SYSTEM GROUND DIGITAL GROUND PLANE k CLOCK SOURCE 9 F 9 F Figure. Connections for Singe Suppy Operation Figure. Connections for Dua Suppy Operation 9fa

7 APPLICATIONS INFORMATION Temperature Behavior The power suppy current of the LTC9- has a positive temperature coefficient. The GBW product of its interna op amps is neary constant and the speed of the device does not degrade at high temperatures. Figures a, b and c show the behavior of the maximum passband of the device for various suppies and temperatures. The fiter, especiay at ±V suppy, has a passband behavior which is neary temperature independent. Cock Feedthrough The cock feedthrough is defined as the RMS vaue of the cock frequency and its harmonics that are present at the fiter s output pin (). The cock feedthrough is tested with the input pin () shorted to the AGND pin and depends on PC board ayout and on the vaue of the power suppies. With proper ayout techniques the vaues of the cock feedthrough are shown on Tabe. Tabe. Cock Feedthrough V S CLOCK FEEDTHROUGH.V μv RMS V μv RMS ±V μvrms LTC9- Any parasitic switching transients during the rise and fa edges of the incoming cock are not part of the cock feedthrough specifi cations. Switching transients have frequency contents much higher than the appied cock; their ampitude strongy depends on scope probing techniques as we as grounding and power suppy bypassing. The cock feedthrough can be reduced, if bothersome, by adding a singe RC owpass fiter at the output pin () of the LTC9-. Wideband Noise The wideband noise of the fiter is the tota RMS vaue of the device s noise spectra density and determines the operating signa-to-noise ratio. Most of the wideband noise frequency contents ie within the fiter passband. The wideband noise cannot be reduced by adding post fitering. The tota wideband noise is neary independent of the cock frequency and depends sighty on the power suppy votage (see Tabe ). The cock feedthrough speci fications are not part of the wideband noise. Tabe. Wideband Noise V S WIDEBAND NOISE.V μv RMS V μv RMS ±V μv RMS GAIN () V S =.V f = khz =.V RMS T A = C T A = C T A = C GAIN () V S = V f = MHz =.V RMS T A = C T A = C T A = C GAIN () f =.MHz = V RMS T A = C T A = C T A = C Fa Fb. 9 9 Fc Figure a Figure b Figure c 9fa

8 LTC9- APPLICATIONS INFORMATION Aiasing Aiasing is an inherent phenomenon of samped data systems and it occurs for input frequencies approaching the samping frequency. The interna samping frequency of the LTC9- is times its cutoff frequency. For instance, if a 9kHz, mv RMS signa is appied at the input of an LTC9- operating with a khz cock, a khz, μv RMS aias signa wi appear at the fiter output. Tabe shows detais. Tabe. Aiasing (f = khz) INPUT FREQUENCY ( = V RMS ) (khz) f /f C = :, f CUTOFF = khz 9 (or ) 9 (or ) 9 (or ) 9. (or.) 99 (or ) 99. (or.) OUTPUT LEVEL (Reative to Input) () OUTPUT FREQUENCY (Aiased Frequency) (khz) TYPICAL APPLICATIONS Singe V Operation with Power Shutdown SHUTDOWN ON V CMOS LOGIC AGND.μF.μF V + V LTC9- f khz V V 9- TA Singe.V Suppy Operation with Output Buffer.V.μF.μF.μF AGND V + V LTC9- + / LT f khz.v V 9 TA 9fa

9 PACKAGE DESCRIPTION N Package -Lead PDIP (Narrow. Inch) (Reference LTC DWG # --).* (.) MAX LTC9-. ±.* (. ±.).. (..).. (..). ±. (. ±.).. (..) ( ). (.) TYP. (.) BSC NOTE: INCHES. DIMENSIONS ARE MILLIMETERS *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED. INCH (.mm). (.) MIN. ±. (. ±.). (.) MIN N S Package -Lead Pastic Sma Outine (Narrow. Inch) (Reference LTC DWG # --). BSC. ±..9.9 (..) NOTE. MIN. ±... (.9.9).. (..9) NOTE. ±. TYP RECOMMENDED SOLDER PAD LAYOUT.. (..).. (..) TYP..9 (..).. (..)....9 (..) (..) NOTE: INCHES TYP. DIMENSIONS IN (MILLIMETERS). DRAWING NOT TO SCALE. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED." (.mm). (.) BSC Information furnished by Linear Technoogy Corporation is beieved to be accurate and reiabe. However, no responsibiity is assumed for its use. Linear Technoogy Corporation makes no representation that the interconnection of its circuits as described herein wi not infringe on existing patent rights. SO 9fa 9

10 LTC9- TYPICAL APPLICATION Dua Suppy Operation f IN = khz AGND V V + V V.μF LTC9-.μF f khz f C = khz V V THD + NOISE (). INPUT VOLTAGE (V RMS ) 9 TA RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC Very Low Noise, High Accuracy, Quad Universa Fiter Buiding Bock User-Confi gurabe, SSOP Package LTC9- Singe Suppy, Very Low Power, Eiptic LPF : f /f C Ratio, -Pin SO Package LTC- Low Power th Order Butterworth LPF : and : f /f C Ratio LTC- Low Power th Order Eiptic LPF : and : f /f C Ratio LTC- Low Power th Order Linear Phase LPF : and : f /f C Ratio LT 9 REV A PRINTED IN USA Linear Technoogy Corporation McCarthy Bvd., Mipitas, CA 9- () -9 FAX: () - LINEAR TECHNOLOGY CORPORATION 99 9fa