LTC1060CSW View Datasheet(PDF) - Linear Technology

Part Name

Description

Manufacturer

LTC1060CSW

Universal Dual Filter Building Block

Linear Technology 

LTC1060

COMM E TS ON THE M ODES OF OPERATIO

mode 2b section (Figure 22), has a gain exceeding unity

which limits the dynamic range of the overall filter. For

very selective bandpass/bandreject filters, the mode 3a

approach, as in Figure 20, yields better dynamic range

since the external op amp helps to optimize the dynamics

of the output nodes of the LTC1060.

RH1

RL1

RG

R41

R31

R21

R11

VIN

–7.5V

V+ = 7.5V

T2L OR CMOS

LTC1060

RL2

1

LPA

2

BPA

3

HPA

4

INVA

5

S1A

20 R42

LPB

19 R32

BPB

18 R22

HPB

RH2

17

INVB

16

S1B

6

SA/B

7 VA+

8 VD+

9

LSh

15

AGND

VA– 14

VD– 13

12

50/100

–7.5V

7.5V

10

CLKA

11

CLKB

–

EXTERNAL

OP AMP

+

CLOCK IN

PRECISE RESISTOR VALUES

R11 = 155.93k R21 = 5k

R31 = 152k

R41 = 5.27k

RH1 = 13.2k

R42 = 5k

RL1 = 10.74k

RL2 = 6.11k

R22 = 5.26k

RH2 = 5k

R32 = 151.8k

RG = 37.3k

NOTE: FOR CLOCK FREQUENCIES ABOVE 700kHz, A 12pF CAPACITOR ACROSS R41 AND A 20pF

CAPACITOR ACROSS R42 WERE USED TO PREVENT THE PASSBAND RIPPLE FROM ANY

ADDITIONAL PEAKING

VOUT

LTC1060 • CM02

Figure 20. Combining Mode 3 with Mode 3a to Make The 4th Order BP Filter of Figure 21 with Improved

Dynamics. The Gain at Each Output Node is ≤ 0dB for all Input Frequencies.

0dB

–10dB

fCLK = 100kHz

0dB

–10dB

fCLK = 1MHz

–20dB

–30dB

–20dB

–30dB

–40dB

–40dB

–50dB

–50dB

1.5kHz 1.75kHz 2kHz 2.25kHz 2.5kHz

15kHz 17.5kHz 20kHz 22.5kHz 25kHz

TLC1060 • CMO03

Figure 21. The BP Filter of Figure 20, When Swept From a 2kHz to 20kHz Center Frequency.

1060fb

17

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