Linear DC266B-A, DC266B-B Demo Manual

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Description

DEMO MANUAL DC266B

LTC1562/LTC1562-2

Quad 2nd Order Active RC Filter IC

Demonstration circuit DC266B-A is for the evaluation of 8th order filter circuits using an LTC1562 (no dash) and DC266B-B for an LTC1562-2. LTC1562 and LTC1562-2 are quad 2nd order active-RC filter building blocks. The LTC1562 or LTC1562-2 2nd order sections can be con figured with external resistors to implement lowpass and narrow or wide band bandpass filters. The frequency range for a

lowpass

filter is 10kHz to 150kHz and 20kHz to

For other possible LTC1562 or LTC1562-2 configurations, the DC226B-A and DC226B-B have unused pads for 0805 surface mount resistors and capacitors preconfigured with PCB traces to allow for the following filter circuits:

1. 8th order lowpass filter

2. Dual 4th or 5th order lowpass filter

3. 8th order narrow band bandpass

300kHz for the LTC1562 and LTC1562-2 respectively. The frequency range for a bandpass filter is 20kHz to 120kHz and 40kHz to 250kHz for the LTC1562 and LTC1562-2 respectively (the LTC1562A is higher precision version of the LTC1562).

For testing and evaluation, the DC266B-A is configured as an 8th order, 50kHz bandpass filter and the DC266B-B is configured as an 8th order, 200kHz bandpass filter.

4. 8th order wide band bandpass.

Refer to the LTC1562 or LTC1562-2 data sheet for com prehensive filter design information.

Design files for this circuit board are available at

http://www.linear.com/demo/DC266B

L, LT, LTC, LTM, Linear Technology, LTspce, FilterCAD and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.

Ltc1562 anD Ltc1562-2 BLock Diagram

–

SHUTDOWN SWITCH

–

PINS 4, 7, 14

AND 17 MUST BE

CONNECTED TO

–

, PIN 16

10 9 8 1 2 3

INV V1 V2

A B

–

∫ ∫

2ND ORDER SECTIONS

SHDN

AGND

D C

∫ ∫

–

C C

11 12 13 20 19 18

INV V1 V2 INV V1 V2

A B

2ND ORDER LOWPASS (V2) AND BANDPASS (V1) 2ND ORDER BANDPASS (V2) AND HIGHPASS (V1)

INV V1 V2

–

∫ ∫

*100kHz FOR

LTC1562 AND 200kHz FOR LTC1562-2

INV V1 V2

–

INV V1 V2

–

THE MAXIMUM FREQUENCY ERROR IS ±0.6% FOR LTC162A, ±1.0% FOR LTC1562 AND ±1.7% FOR LTC1562-2

DC266 BD

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DEMO MANUAL DC266B

Quick start proceDure

See Figure 1 for proper measurement equipment setup and follow the procedure below.

1. Set SW1 to DUAL.

2. With power off, connect a dual 5V power supply to +V and –V.

3. Connect a function generator to IN.

4. For a DC266B-A, set the function generator to a 2V 50kHz, sine wave.

5. For a DC266B-B, set the function generator to a 2V 200kHz, sine wave.

P-P

6. Connect an oscilloscope channel to OUT.

7. For a DC266B-A, set the scaling of an oscilloscope to 1V/20µs per division.

For a DC266B-B, set the scaling of an oscilloscope to

1V/5µs per division.

8. Power up the system and the oscilloscope should show

sine wave.

P-P

9. To test stopband attenuation of DC266B-A, set the input frequency to 25kHz or 75kHz.

10. To test stopband attenuation of DC266B-B, set the input frequency to 150kHz or 250kHz.

Figure 1. Quick Start Test Equipment Setup

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Dc266B FiLter circuits

INV

AGND

–

INV

LTC1562A

OUT

–

V1 AC1

V2 5

R21 46.4k

RQ2 68.1k

R22 39.2k

RQ1 61.9k

R23

53.6k

RQ3 88.7k

R24 33.2k

RQ4 100k

0.1µF

Z1C

61.9k

Z1A

61.9k

RIN1 150k

Z1B

61.9k

V3 –5

0.1µF

LTC1562A LINEAR PHASE 8TH ORDER BPF

(SHORT TRANSIENT RESPONSE)

CENTER

= 50kHz

–3dB BW = 10kHz

LTC1562A, ±0.6% 2ND ORDER FREQUENCY ERROR

DUAL SUPPLY CIRCUIT

.ac oct 250 5k 200k

+–+–+ –

DC266 F02a

FREQUENCY

5kHz

50kHz

200kHz

–100

–90

–80

–70

–60

–50

–40

–30

–20

–10

Magnitude vs Frequency

DC266 F02b

DEMO MANUAL DC266B

For testing and evaluation, the DC266B-A is configured as an 8th order, 50kHz bandpass filter (Figure 2) and the DC266B-B is configured as an 8th order, 200kHz bandpass filter (Figure 3). The external resistors for the 50kHz and 200kHz bandpass filter are ±0.1% precision to highlight the frequency accuracy of the LTC1562A or LTC1562-2 (±0.6% and ±1.7% 2nd order frequency error for the LTC1562A and LTC1562-2 respectively).

NOTE 1: The precision of external resistors and capaci

tors depend on the filter type. A lowpass and wideband bandpass filter can be implemented with ±1% resistors and ±5% capacitors. A narrowband bandpass filter requires ±0.1% resistors and 1% capacitors to implement a 100% reliable manufacturing lot.

NOTE 2: In a dual supply operation, the DC266B connects

–

two Schottky diodes in series with the V

supply. The diodes provide 100% protection for possible 2nd order oscillations when a V1 or V2

output

approaches the supply rails.

The V1 diodes can be shorted out on the board if testing the filter circuit with an input that saturates the output nodes does not produce any oscillations.

Re-Configuring the DC266B

Removing the default passive components (RIN1, RQ1, R21, Z1B, RQ2, R22, Z1C, RQ3, R23, Z1A, RQ4, R24) a variety of bandpass and lowpass LTC1562/LTC1562-2 filter circuits can be implemented.

The LTC1562 and LTC1562-2 data sheets provide filter design guides and a variety of pre-designed filter circuits.

The typical f A guideline is to consider an f

and gain error can be evaluated by LTspice®.*

error greater than 3% or

a passband gain peak greater than 2dB as an indication the circuit is operating beyond a reliable f

error less than 3% or gain error less than 2dB can be

frequency (an

adjusted using the external resistors).

*LTspice is a high performance simulator, schematic capture and waveform viewer available for free download at www.linear.com/LTspice.

150k

RIN1

150k

GAIN

61.9k GAIN

•

61.9k Z1B

GAIN =

RIN1=

Z1B =

MAXIMUM GAIN: 40dB

Figure 2. The Default DC266B-A Circuit

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DEMO MANUAL DC266B

INV

AGND

–

INV

LTC1562-2

OUT

–

V1 AC1

V2 5

R21 9.09k

RQ2 23.2k

R22 7.32k

RQ1 23.2k

R23

10.5k

RQ3 29.4k

R24 6.34k

RQ4 29.4k

0.1µF

Z1C

23.2k

Z1A

23.2k

RIN1

23.2k

Z1B

23.2k

V3 –5

0.1µF

LTC1562-2 LINEAR PHASE 8TH ORDER BPF

(SHORT TRANSIENT RESPONSE)

CENTER

= 200kHz

–3dB BW = 40kHz

LTC1562-2, ±1.7% 2ND ORDER FREQUENCY ERROR

DUAL SUPPLY CIRCUIT

.ac oct 250 20k 800k

+–+–+ –

DC266 F03a

INV

AGND

–

INV

LTC1562A

+–+ –

CIN1 (C

)

Z2B

)

RQ2 205k

OUT

V1 AC1

V2 5

R21 41.2k

R22 41.2

RQ1 205k

R23

42.2k

RQ3 232k

R24 39.2k

RQ4 232k

0.1µF

Z1A 39pF

Z2C

232k

Z2A 301k

Z1C 18pF

0.1µF

LTC1562A HIGH SELECTIVITY 8TH ORDER BPF f

CENTER

= 50kHz

–3dB = 2kHz

LTC1562A 2ND ORDER SECTION FREQUENCY ERROR: ±0.6%

SINGLE SUPPLY CIRCUIT

DC266 F04a

GAIN C

0dB 6.8pF 10dB 10pF 21dB 22pF 31dB 39pF 40dB 68pF MAXIMUM GAIN, 40dB

.ac lin 500 10k 100k

.param CIN = 6.8p

FREQUENCY

20kHz

200kHz

800kHz

–100

–90

–80

–70

–60

–50

–40

–30

–20

–10

Magnitude vs Frequency

DC266 F03b

FREQUENCY (Hz)

5kHz

50kHz

200kHz

–100

–90

–80

–70

–60

–50

–40

–30

–20

–10

Magnitude vs Frequency

DC266 F04b

Dc266B FiLter circuits

23.2k RIN1

23.2k GAIN

•

23.2k Z1B

GAIN =

RIN1=

Z1B =

MAXIMUM GAIN: 20dB

Figure 3. The Default DC266B-B Circuit

ALL RESISTORS: 0.1% Z1C AND Z1A CAPACITORS: 1% CIN1 AND Z2B: 5%

Figure 4. Reconfigured for LTC1562A 8th Order, 50kHz High Selectivity, Bandpass Filter

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Dc266B FiLter circuits

INV

AGND

–

INV

LTC1562A

+–+ –

RIN1

GAIN

)

Z1B

GAIN

)

RQ2 100k

OUT

V1 AC1

2.5

V2 5

R21 10.2k

R22 10.2

RQ1 100k

R23

10.5k

RQ3 115k

R24 9.76k

RQ4 115k

0.1µF

Z1A 33pF

Z2C 59k

Z2A 80.6k

Z1C 18pF

0.1µF

LTC1562A HIGH SELECTIVITY 8TH ORDER BPF f

CENTER

= 100kHz

–3dB = 4kHz

LTC1562A 2ND ORDER SECTION FREQUENCY ERROR: ±0.6%

SINGLE SUPPLY CIRCUIT

DC266 F05a

.ac lin 500 20k 200k

.param R

GAIN

= 140k

FREQUENCY (Hz)

10kHz

100kHz

400kHz

–100

–90

–80

–70

–60

–50

–40

–30

–20

–10

Magnitude vs Frequency

DC266 F05b

⎛

⎞

140k

GAIN =

⎜

⎟

⎝

⎠

GAIN

140k

GAIN

MAXIMUM GAIN: 26dB

DEMO MANUAL DC266B

RESISTORS: 0.1% (RIN1 AND Z1B: 1%) Z1C AND Z1A CAPACITORS: 1%

Figure 5. Reconfigured for LTC1562A 8th Order, 100kHz High Selectivity, Bandpass Filter

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 representa-

tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.

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DEMO MANUAL DC266B

DEMONSTRATION BOARD IMPORTANT NOTICE

Linear Technology Corporation (LTC) provides the enclosed product(s) under the following AS IS conditions:

This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT OR EVALUATION PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO BOARD herein may not be complete in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations.

If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the date of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.

The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user releases LTC from all claims arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or agency certified (FCC, UL, CE, etc.).

No License is granted under any patent right or other intellectual property whatsoever. LTC assumes no liability for applications assistance,

customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.

LTC currently services a variety of customers for products around the world, and therefore this transaction is not exclusive.

Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training and

observe good laboratory practice standards. Common sense is encouraged.

This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LTC application engineer.

Mailing Address:

Linear Technology

1630 McCarthy Blvd.

Milpitas, CA 95035

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com

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LT 1116 • PRINTED IN USA