1 ltc1560-1 sn15601 15601fs 1mhz/500khz continuous time, low noise, lowpass elliptic filter features 5th order, 1mhz elliptic filter in so-8 package pin selectable 1mhz/500khz cutoff frequency signal-to-noise ratio (snr): 75db signal-to-noise ratio with 63db thd: 69db passband ripple (f cutoff = 1mhz): 0.3db stopband attenuation better than 60db no external components required either 500khz (pin 5 to v + ) or 1mhz (pin 5 to v ). when programmed for 1mhz, the passband ripple is typically 0.2db up to 0.55f cutoff and 0.3db to 0.9f cutoff . the transition band gain is 24db at 1.4f cutoff and 51db at 2f cutoff . stopband attenuation is 63db at 2.43f cutoff and above, remaining at least 60db to 10mhz with properboard layout. when the ltc1560-1 is programmed for f cutoff = 500khz, the filter response closely follows the 1mhz case with the exception of passband flatness nearthe cutoff frequency; the gain at f cutoff is 1.3db. the ltc1560-1, unlike other high frequency filters, isdesigned for low noise and low distortion. with a 1v rms input signal, the signal-to-noise ratio is 69db and the thd is 63db. the maximum snr of 75db is obtained with a 2.1v rms input signal. this results in 46db thd. the ltc1560-1 operates with 5v supplies, has a power saving mode and is available in an so-8 surface mountpackage. other cutoff frequencies from 450khz to 1.5mhz can be obtained. demo board dc135a is available for the ltc1560-1. for more information please contact ltc marketing. frequency (mhz) 0.1 ?0 gain (db) ?0 ?0 ?0 ?0 11 0 1560-1 ta02 10 ?0 ?0 ?0 ?0 0 f cutoff = 1mhz/500khz frequency response , ltc and lt are registered trademarks of linear technology corporation. typical applicatio n u descriptio n u the ltc 1560-1 is a 5th order, continuous-time, lowpass filter. the elliptic transfer function of the ltc1560-1 was carefully chosen to reach a compromise between selectiv- ity, for antialiasing applications, and transient response. the filter cutoff frequency, f cutoff , is pin selectable to antialiasing filters smoothing or reconstruction filters communication filters applicatio n s u v in v out 5v (or 5v) 0.01 f 0.1 f 0.1 f ?v 1560-1 ta01 0.01 f ?v 1mhz 5v 500khz gndv v + gnd v in 14 3 2 85 6 7 v out shdn 0.5f c /f c ltc1560-1 1mhz/500khz elliptic lowpass filter downloaded from: http:///
2 ltc1560-1 sn15601 15601fs absolute m axi m u m ratings w ww u package/order i n for m atio n w u u total supply voltage (v + to v ) ............................. 12v power dissipation ............................................. 400mw burn-in voltage ................................................... 5.5v operating temperature range ltc1560-1c ........................................... 0 c to 70 c ltc1560-1i ....................................... 40 c to 85 c maximum junction temperature ......................... 150 c storage temperature range ................. 65 c to 150 c lead temperature (soldering, 10 sec).................. 300 c order part number ltc1560-1cs8ltc1560-1is8 the denotes specifications which apply over the full operating temperature range.note 1: to properly measure high frequency characteristics of the filter, a noninverting output buffer is recommended as shown on the demo board connection diagram, figure 2. a small resistor (e.g. 100 w ) can also be used instead of the buffer to isolate any high capacitive load (c l > 10pf) from the filter output.note 2: the stopband gain at 2.44mhz is guaranteed by design. parameter conditions min typ max units operating supply voltage range 4.5 5.0 5.5 v passband gain (f cutoff = 1mhz) v in = 0.5v rms ,f in = 20khz 0.17 db f in = 100khz 0.3 0.18 0.6 db f in = 300khz 0.08 db f in = 550khz (gain relative to 100khz) 0.35 0.05 0.3 db f in = 850khz (gain relative to 100khz) 0.8 0.3 0 db f in = 950khz (gain relative to 100khz) 3.0 0.6 0.5 db f in = f cutoff = 1mhz (gain relative to 100khz) 5.0 1.0 1.0 db transition band gain (note 1) v in = 0.5v rms ,f in = 1.4mhz ?4 18 db f in = 1.9mhz 42 db f in = 2.0mhz 51 db stopband gain (f cutoff = 1mhz) (note 2) f in = 2.44mhz ?0 ?5 db f in = 3.0mhz 68 db f in = 6.0mhz 66.1 db passband gain (f cutoff = 500khz) f in = 100khz, pin 5 = 5v 0.14 db f in = f cutoff = 500khz 4 1.6 0.5 db f in = 1.4mhz 45 db output voltage swing r l = 5k 2.20 3v r l = 5k 1.75 v output dc offset (v os ) 250 mv power supply current (i s ) 22 29 ma power supply current in shutdown mode pin 7 at 5v 1 ma total output noise v in (pin 2) tied to ground, f cutoff = 1mhz, bw = 2mhz 350 m v rms v in (pin 2) tied to ground, f cutoff = 0.5mhz, bw = 1mhz 322 m v rms total harmonic distortion (thd) v in = 1v rms , f in = 200khz, f cutoff = 1mhz, bw = 1mhz 63 db f in = 300khz, f cutoff = 1mhz, bw = 1mhz 61 db f in = 1mhz, f cutoff = 1mhz, bw = 2mhz 62 db f in = 300khz, f cutoff = 0.5mhz, bw = 1mhz 62 db f in = 500khz, f cutoff = 0.5mhz, bw = 1mhz 63 db input resistance (r in ) 681 0 k w electrical characteristics v s = 5v, t a = 25 c, pin 5 = 5v (f cutoff = 1mhz), pin 7 = 0v unless otherwise specified. s8 part marking 1560115601i consult factory for military grade parts. t jmax = 150 c, q ja = 125 c/ w 12 3 4 87 6 5 top view v out shdnv + gnd v in gnd v s8 package 8-lead plastic so 0.5f c/ f c downloaded from: http:///
3 ltc1560-1 sn15601 15601fs frequency (mhz) 0.1 gain (db) 0 0.2 0.4 0.6 0.5 1560-1 g03 0.2 0.4 0.6 0.2 0.3 0.4 0.6 0.7 0.8 0.9 1.0 f cutoff = 1mhz frequency (mhz) 0 gain (db) ?0 ?0 ?0 2.0 1560-1 g02 ?0 ?0 ?0 ?0 0.5 1.0 1.5 ?0 0 10 ?0 f cutoff = 500khz frequency response passband gain group delay passband gain frequency (mhz) ?.4 gain (db) ?.2 0.8 0.6 0.4 0.3 0.4 0.4 1560-1 g04 ?.0 0.2 0.1 0.5 0.2 0 0.2 f cutoff = 500khz frequency (mhz) 0 0 group delay ( m s) 0.25 0.75 1.00 1.25 0.2 0.4 0.5 0.6 0.7 0.8 0.9 1.0 2.25 1560-1 g06 0.50 0.1 0.3 1.50 1.75 2.00 f cutoff = 500khz frequency (mhz) 0 gain (db) ?0 ?0 ?0 4 1560-1 g01 ?0 ?0 ?0 1 2 3 ?0 0 10 ?0 f cutoff = 1mhz frequency response typical perfor m a n ce characteristics u w group delay frequency (mhz) 0 group delay ( m s) 0.8 1.2 2.0 1560-1 g05 0.4 0 0.50 1.0 1.50 0.25 0.75 1.25 1.75 1.60.6 1.00.2 1.4 f cutoff = 1mhz phase vs frequency frequency (khz) 20 phase (deg) ?5 0 500 660 820 980 1560-1 g08 ?0 135 225 270 180 340 180 f cutoff = 1mhz phase vs frequency frequency (khz) 20 phase (deg) ?5 0 45 500 420 1560-1 g07 ?0 135 225 260 100 180 340 180 f cutoff = 500khz downloaded from: http:///
4 ltc1560-1 sn15601 15601fs typical perfor m a n ce characteristics u w frequency (mhz) 0.1 0 output noise ( m v rms ) 12 24 36 48 0.5 1.5 1.0 1560-1 g11 60 6 18 30 42 54 f cutoff = 1mhz total output noise = 232 m v rms output noise vs frequency 2 m s/div f cutoff = 0.5mhz v in = 5v p-p f in = 50khz 1v/div 1560-1 g09 transient response transient response 2 m s/div f cutoff = 1mhz v in = 5v p-p f in = 50khz 1v/div 1560-1 g10 output noise vs frequency dynamic range input voltage (v rms ) ?0 ?0 ?0 ?0 ?0 ?0 ?0 ?0 1560-1 g13 thd + noise 0.1 3 1 f cutoff = 500khz or 1mhz f in = 45khz frequency (khz) 50 0 output noise ( m v rms ) 12 24 36 48 200 400 600 100 1560-1 g12 60 6 18 30 42 54 f cutoff = 0.5mhz total output noise = 198 m v rms input frequency (khz) 40 thd (db) ?2 ?4 ?6 ?8 ?0 ?2 ?4 ?6 ?8 ?0 ?2 80 120 140 1560-1 g15 60 100 160 180 200 f cutoff = 1mhz v in = 1v rms s/n = 72db v in = 0.6v rms s/n = 68db thd + noise vs input frequency thd + noise vs input frequency input frequency (khz) 40 thd (db) ?2 ?4 ?6 ?8 ?0 ?2 ?4 ?6 ?8 ?0 ?2 80 120 140 1560-1 g14 60 100 160 180 200 f cutoff = 500khz v in = 1v rms s/n = 74db v in = 0.6v rms s/n = 69.5db downloaded from: http:///
5 ltc1560-1 sn15601 15601fs pi n fu n ctio n s uuu g nd (pins 1, 3) : analog ground pins. the quality of the analog ground can affect the filter performance. for dualsupply operation the analog ground pin should be con- nected to an analog ground plane surrounding the pack- age. the analog ground plane should be connected to a digital ground plane (if any) at a single point. for single supply operation, the analog ground pin should be biased at one-half the power supply across the device (see figure 1) and the analog ground plane should then be connected to v (pin 4). v in (pin 2) : the filter input is internally connected to the inverting input of a high frequency op amp through an 8kresistor. v , v + (pins 4, 6) : power supply pins. the negative and positive power supply (pins 4 and 6 respectively) shouldbe decoupled with a 0.1 m f capacitor in parallel with a 0.01 m f. both capacitors should be types designed for decoupling video frequencies and they should be placedas close as possible to the power supply pins of the filter. parallel routing of high frequency signal paths should be avoided; they will couple into the device? power supply pins and cause gain inaccuracy and stopband degrada- tion. the power supplies can be applied in any order, thatis, the positive supply can be applied before the negative supply and vice versa. switching power supplies are not recommended. 0.5f c /f c (pin 5) : by tying pin 5 high the filter cutoff frequency is internally programmed for 500khz. by tyingpin 5 low the cutoff frequency will switch to 1mhz. pin 5 should not be left floating. the logic threshold of pin 5 is approximately 0.4 times the total power supply across the device. shdn (pin 7) : shutdown. under normal operating condi- tions, pin 7 should be shorted either to the analog ground(pin 1) or to v (pin 4). if pin 7 is pulled high to v + , the filter operation will stop and the ic will be placed in a powersaving mode. the power supply current will then be reduced to 1ma. for a 5v supply, the logic threshold of pin 7 is 2.5v. pin 7 is internally connected to the analogground pin via a 50k resistor. v out (pin 8) : the filter output pin can sink or source 1ma. the total harmonic distortion of the filter will degradewhen driving coaxial cables or loads less than 10k without an output buffer. figure 1. connections for single supply operation v + 1560-1 f01 v in v out 0.01 m f 0.1 m f 0.01 m f 1 m f 10k 10k gnd or v + analog ground plane system ground digital ground plane gndv v + gnd v in 14 3 2 85 6 7 v out shdn 0.5f c /f c ltc1560-1 downloaded from: http:///
6 ltc1560-1 sn15601 15601fs applicatio n s i n for m atio n wu u u the performance of the ltc1560-1 can be easily evaluatedby using demo board 135a which can be obtained through ltc marketing. figure 2 shows the circuit connection of the ltc1560-1 in demo board 135a. the filter cutoff frequency can be switched via s2 and the power savings mode can also be activated via s1. the output of the filter is buffered by u2, an lt 1360 op amp. the buffering can be bypassed by using jumper jp1. figure 3 shows thedemo board layout. figure 3. demo board 135a layout unbuffered output filter input ground + 5v filter supply ground 5v filter supply buffered output ground +15v buffer supply 15v buffer supply 1560-1 f03 12 3 4 87 6 5 u1 ltc1560-1 jp1 jumper r1 1k 2 74 3 6 v out shdn v + 0.5f c /f c gndv in gndv c10.01 m f c90.01 m f c101 m f 25vy5v c81 m f 25vy5v c61 m f 16vx7r c50.22 m f c40.01 m f c20.22 m f e2 tp ?v c31 m f 16vx7r s1 gs01mscke s2 gs01mscke e1 tp v in 32 1 r2 332 w + u2 lt1360cs8 c70.01 m f e10tp gnd e9tp gnd e8tp gnd e7tp 5v 1560-1 f02 e6tp 15v e5tp out1 e4tp 15v e3tp out2 figure 2. demo board 135a connection diagram downloaded from: http:///
7 ltc1560-1 sn15601 15601fs 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 n s n u augmenting the ltc1560-1 for improved delay flatness gain vs frequency 1mhz lowpass filter cascaded with a 30khz 3rd order highpass filter frequency (khz) 0.1 ?0 gain (db) ?0 ?0 ?0 ?0 ?0 1 10 100 1000 10,000 1560-1 ta10 ?0 ?0 ?0 100 110 0 10 + + ?v 5v 0.1 m f 0.1 m f 2.61k 560pf 560pf 560pf 3 1k 23.7k 2 4 8 1/2 lt1364 1 65 1/2 lt1364 7 0.1 m f 39pf (or 5v) 0.01 m f 0.1 m f 0.01 m f v in 1560-1 ta09 560pf gndv v + gnd v in 14 3 2 85 6 7 v out shdn 0.5f c /f c ltc1560-1 + + 5v 2 6.49k 6.65k 49.9 w 22pf 0.1 m f 0.1 m f 22pf 9.75k 20k 40.2k 3 v out 1/2 lt1364 1 65 4 8 5v 1/2 lt1364 ?v 7 0.1 m f (or 5v) 0.01 m f 0.01 m f 0.1 m f v in ?v 1560-1 ta05 gndv v + gnd v in 14 3 2 85 6 7 v out shdn 0.5f c /f c ltc1560-1 2-level eye diagram of the equalized filter 2mbps/s 1560-1 ta06 downloaded from: http:///
8 ltc1560-1 sn15601 15601fs linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax: (408) 434-0507 telex: 499-3977 www.linear-tech.com ? linear technology corporation 1997 lt/gp 1197 4k ? printed in usa typical applicatio n u package descriptio n u dimensions in inches (millimeters) unless otherwise noted. related parts part number description comments lt1360/lt1361/ 50mhz, 800v/ m s op amp(s) single/dual/quad c-load tm op amps lt1362 ltc1562 active rc quad universal filter very low noise, low distortion c-load is a trademark of linear technology corporation s8 package 8-lead plastic small outline (narrow 0.150) (ltc dwg # 05-08-1610) 0.016 ?0.0500.406 ?1.270 0.010 ?0.020 (0.254 ?0.508) 45 0 ?8 typ 0.008 ?0.010 (0.203 ?0.254) so8 0695 0.053 ?0.069 (1.346 ?1.752) 0.014 ?0.019 (0.355 ?0.483) 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 * ** + 15v 15v 0.1 m f 0.1 m f 5v 3 1k 2 4 v out 7 lt1360 8 0.1 m f (or 5v) 0.01 m f 0.01 m f 8.1k 0.1 m f v in 300pf ?v 1560-1 ta07 300pf gndv v + gnd v in 14 3 2 85 6 7 v out shdn 0.5f c /f c ltc1560-1 frequency (khz) ?0 ?0 ?0 ?0 ?0 ?0 0 ?0 ?0 ?0 10 gain (db) 10000 1560-1 ta08 20 100 1000 a simple highpass/lowpass filter measured frequency response downloaded from: http:///
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