Linear Technology LTC1560-1 Datasheet

LTC1560-1

FREQUENCY (MHz)

0.1

–90

GAIN (dB)

–70

–50

–30

–10

110

1560-1 TA02

10

–80

–60

–40

–20

0

f

CUTOFF

= 1MHz/500kHz

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

■

Stopband Attenuation Better Than 60dB

■

No External Components Required

= 1MHz): ±0.3dB

CUTOFF

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APPLICATIONS

■

Antialiasing Filters

■

Smoothing or Reconstruction Filters

■

Communication Filters

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DESCRIPTION

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 selectiv­ity, for antialiasing applications, and transient response.

The filter cutoff frequency, f

, is pin selectable to

CUTOFF

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
transition band gain is –24dB at 1.4f
2f

. Stopband attenuation is 63dB at 2.43f

CUTOFF

and ±0.3dB to 0.9f

CUTOFF

CUTOFF

. The

CUTOFF

and –51dB at

and

CUTOFF

above, remaining at least 60dB to 10MHz with proper
board layout. When the LTC1560-1 is programmed for
f

= 500kHz, the filter response closely follows the

CUTOFF

1MHz case with the exception of passband flatness near
the cutoff frequency; the gain at f

CUTOFF

is –1.3dB.

The LTC1560-1, unlike other high frequency filters, is
designed 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

input signal. This results in –46dB THD.

RMS

The LTC1560-1 operates with ±5V supplies, has a power
saving mode and is available in an SO-8 surface mount
package.

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.

, LTC and LT are registered trademarks of Linear Technology Corporation.

TYPICAL APPLICATION

1MHz/500kHz Elliptic Lowpass Filter

1

GND

2

V

3

GND

4

V

–5V

0.1µF

V

IN

0.01µF

IN

LTC1560-1

–

0.5f

V

OUT

SHDN

V

C/fC

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Frequency Response

8

V

OUT

7

(OR –5V)

6

+

5

0.1µF

5V

0.01µF

–5V
1MHz
5V
500kHz

1560-1 TA01

1

LTC1560-1

WW

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ABSOLUTE MAXIMUM RATINGS

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

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PACKAGE/ORDER INFORMATION

TOP VIEW

GND

1

V



2

IN

GND

3

–

V

4

S8 PACKAGE

8-LEAD PLASTIC SO

T

= 150°C, θJA = 125°C/ W

JMAX

Consult factory for Military grade parts.

V



8

OUT

SHDN

7

+

V



6



0.5fC/f

5

C

ORDER PART

NUMBER

LTC1560-1CS8
LTC1560-1IS8

S8 PART MARKING

15601
15601I

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ELECTRICAL CHARACTERISTICS

VS = ±5V, TA = 25°C, Pin 5 = –5V (f

PARAMETER CONDITIONS MIN TYP MAX UNITS

Operating Supply Voltage Range ±4.5 ±5.0 ±5.5 V
Passband Gain (f

Transition Band Gain (Note 1) VIN = 0.5V

Stopband Gain (f

Passband Gain (f

Output Voltage Swing RL = 5k ● ±1.9 ±3V
Output DC Offset (VOS) ±250 mV
Power Supply Current (IS) ● 22 29 mA
Power Supply Current in Shutdown Mode Pin 7 at 5V 1 mA
Total Output Noise VIN (Pin 2) Tied to Ground, f

Total Harmonic Distortion (THD) VIN = 1V

Input Resistance (RIN) ● 6 8 10 kΩ

= 1MHz) VIN = 0.5V

CUTOFF

= 1MHz) (Note 2) fIN = 2.44MHz ● –70 –65 dB

CUTOFF

= 500kHz) fIN = 100kHz, Pin 5 = 5V 0.14 dB

CUTOFF

= 1MHz), Pin 7 = 0V unless otherwise specified.

CUTOFF

= 20kHz 0.17 dB

RMS,fIN

f

= 100kHz ● –0.3 0.18 0.6 dB

IN

f

= 300kHz 0.08 dB

IN

f

= 550kHz (Gain Relative to 100kHz) ● –0.35 0.05 0.3 dB

IN

= 850kHz (Gain Relative to 100kHz) ● –0.8 –0.3 0 dB

f

IN

f

= 950kHz (Gain Relative to 100kHz) ● –3.0 0.6 0.5 dB

IN

f

= f

IN

= 1.4MHz ● –24 –18 dB

RMS,fIN

f

= 1.9MHz –42 dB

IN

f

= 2.0MHz –51 dB

IN

f

= 3.0MHz –68 dB

IN

f

= 6.0MHz –66.1 dB

IN

f

= f

IN

f

= 1.4MHz –45 dB

IN

VIN (Pin 2) Tied to Ground, f

, fIN = 200kHz, f

RMS

f

= 300kHz, f

IN

= 1MHz, f

f

IN

fIN = 300kHz, f
f

= 500kHz, f

IN

= 1MHz (Gain Relative to 100kHz) ● –5.0 – 1.0 1.0 dB

CUTOFF

= 500kHz ● –4 –1.6 0.5 dB

CUTOFF

= 1MHz, BW = 2MHz 350 µV

CUTOFF

= 0.5MHz, BW = 1MHz 322 µV

CUTOFF

= 1MHz, BW = 1MHz –63 dB

CUTOFF

= 1MHz, BW = 1MHz –61 dB

CUTOFF

= 1MHz, BW = 2MHz –62 dB

CUTOFF

= 0.5MHz, BW = 1MHz –62 dB

CUTOFF

= 0.5MHz, BW = 1MHz –63 dB

CUTOFF

RMS
RMS

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

2

connection diagram, Figure 2. A small resistor (e.g. 100Ω) can also be
used instead of the buffer to isolate any high capacitive load (C
from the filter output.

Note 2: The stopband gain at 2.44MHz is guaranteed by design.

> 10pF)

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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

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TYPICAL PERFORMANCE CHARACTERISTICS

LTC1560-1

Frequency Response

10

f

= 1MHz

CUTOFF

0

–10

–20

–30

–40

GAIN (dB)

–50

–60

–70

–80

0.4

0.2

0

–0.2

–0.4

–0.6

GAIN (dB)

–0.8

–1.0

–1.2

–1.4

0

f

CUTOFF

1

= 500kHz

2

FREQUENCY (MHz)

0.20.1 0.5

FREQUENCY (MHz)

3

1560-1 G01

0.3 0.4

1560-1 G04

Frequency Response Passband Gain

10

f

= 500kHz

CUTOFF

0
–10
–20
–30
–40

GAIN (dB)

–50
–60
–70
–80

4

–90

0

Group Delay

1.6
f

CUTOFF

1.4

1.2

1.0

0.8

0.6

GROUP DELAY (µs)

0.4

0.2

0

0

0.25

= 1MHz

0.50

0.5

1.0

FREQUENCY (MHz)

1.0

0.75

FREQUENCY (MHz)

1.25

1.5

1.50

1560-1 G02

1.75

1560-1 G05

2.0

2.0

GROUP DELAY (µs)

2.25

2.00

1.75

1.50

1.25

1.00

0.75

0.50

0.25

Group DelayPassband Gain

0

0

f

= 500kHz

CUTOFF

0.1 0.3

0.2 0.4 0.5 0.6 0.7 0.8 0.9 1.0
FREQUENCY (MHz)

1560-1 G06

Phase vs Frequency

45

f

CUTOFF

0

–45

–90

PHASE (DEG)

–135

–180

–225

20

= 500kHz

180

FREQUENCY (kHz)

Phase vs Frequency

0

–45

–90

–135

PHASE (DEG)

–180

–225

–270

260100

340

500420

1560-1 G07

20

180

340

FREQUENCY (kHz)

f

= 1MHz

CUTOFF

500 660 820 980

1560-1 G08

3