LT1016

20

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

„LINEAR TECHNOLOGY CORPORATION 1991

sn1016 1016fcs LT/TP 0601 1.5K REV C • PRINTED IN USA

RELATED PARTS

PART NUMBER

DESCRIPTION

COMMENTS

LT1116

12ns Single Supply Ground-Sensing Comparator

Single Supply Version of LT1016, LT1016 Pinout and Functionality

LT1394

7ns, UltraFast, Single Supply Comparator

6mA, 100MHz Data Rate, LT1016 Pinout and Functionality

LT1671

60ns, Low Power, Single Supply Comparator

450

mA, Single Supply Comparator, LT1016 Pinout and Functionality

LT1711/LT1712

Single/Dual 4.5ns 3V/5V/

±5V Rail-to-Rail Comparators Rail-to-Rail Inputs and Outputs

LT1713/LT1714

Single/Dual 7ns 3V/5V/

±5V Rail-to-Rail Comparators

5mA per Comparator, Rail-to-Rail Inputs and Outputs

LT1715

Dual 150MHz 4ns 3V/5V Comparator

150MHz Toggle Rate, Independent Input/Output Supplies

LT1719/LT1720/LT1721 Single/Dual/Quad 4.5ns 3V/5V Comparators

4mA per Comparator, Ground-Sensing Rail-to-Rail Inputs and Outputs

APPLICATIO S I FOR ATIO

1Hz to 10MHz V-to-F Converter

The LT1016 and the LT1122 FET input amplifier combine

to form a high speed V-to-F converter in Figure 16. A

variety of techniques is used to achieve a 1Hz to 10MHz

circuit’s dynamic range is 140dB, or seven decades, which

is wider than any commercially available unit. The 10MHz

full-scale frequency is 10 times faster than monolithic

V-to-F’s now available. The theory of operation is based on

the identity Q = CV.

Each time the circuit produces an output pulse, it feeds

back a fixed quantity of charge, Q, to a summing node,

S.

The circuit’s input furnishes a comparison current at the

summing node. This difference current is integrated in

A1’s 68pF feedback capacitor. The amplifier controls the

circuit’s output pulse generator, closing feedback loop

around the integrating amplifier. To maintain the sum-

ming node at zero, the pulse generator runs at a frequency

that permits enough charge pumping to offset the input

signal. Thus, the output frequency is linearly related to the

input voltage.

To trim this circuit, apply 6.000V at the input and adjust the

2k

W pot for 6.000MHz output. Next, excite the circuit with

a 10.000V input and trim the 20k resistor for 10.000MHz

output. Repeat these adjustments until both points are

fixed. Linearity of the circuit is 0.03%, with full-scale drift

of 50ppm/

∞C. The LTC1050 chopper op amp servos the

integrator’s noninverting input and eliminates the need for

a zero trim. Residual zero point error is 0.05Hz/

∞C.

Figure 16. 1Hz to 10MHz V-to-F Converter. Linearity is Better Than 0.03% with 50ppm/

∞C Drift

–

+

–

+

–

+

100

Ω

68pF

1.2k

15V

15V

15V

5V

5V

5V

–5V

–5V

–5V

150pF

+

10

µF

36k

1k

1k

10M

LTC1050

A1

LT1122

A2

LT1016

5pF

0.1

µF

4.7

µF

10MHz

TRIM

A4

LT1010

5V REF

–

+

A3

LT1006

OUTPUT

1Hz TO 10MHz

–15V

15pF

(POLYSTYRENE)

Q1

Q2

Q3

Q4

INPUT

0V TO 10V

2k

6MHz

TRIM

10k*

100k*

100k*

10k

470

Ω

6.8

Ω

LT1034-1.2V

LT1034-2.5V

2.2M*

0.02

µF

1016 F16

20k

LM134

* = 1% METAL FILM/10ppm/

°C

BYPASS ALL ICs WITH 2.2

µF ON

EACH SUPPLY DIRECTLY AT PINS

8

= 2N2369

= 74HC14