LT1016
20
1016fc
LINEAR TECHNOLOGY CORPORATION 1991
LT 0601 1.5K REV C • PRINTED IN USA
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507
●
www.linear.com
relaTeD parTs
applicaTions inForMaTion
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
output. Overrange to 12MHz (V
IN
= 12V) is provided. This
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,
Σ. 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 summing
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
2kΩ
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
–
+
–
+
–
+
100Ω
68pF
1.2k
15V
15V 15V
5V
5V
5V
–5V
–5V
–5V
150pF
+
10F
36k 1k
1k
10M
LTC1050
A1
LT1122
A2
LT1016
5pF
+
0.1µF
4.7µF
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
470Ω
6.8Ω
LT1034-1.2V
LT1034-2.5V
2.2M*
0.02µF
1016 F16
20k
LM134
* = 1% METAL FILM/10ppm/°C
BYPASS ALL ICs WITH 2.2µF
ON EACH SUPPLY DIRECTLY AT PINS
Σ
8
= 2N2369
= 74HC14
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 450µA, 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
