Digital potentiometer system
AssigneeHoneywell International Inc.
InventorsRobert J. Thomas, Michael L. Underhill
Life of this patent
Estimating the term…
Abstract
A system or circuit for simulating a potentiometer, thermistor, or the like. A pulse stream, having a duty cycle which is varied as a changing pulse width or as a differing number of time slices per time period, may be input to the system. The pulse stream to a transistor or switch-like mechanism may allow a controlled connection of a fixed value resistor to a reference voltage or ground to provide various resultant values of impedance or resistance. A measuring circuit connected to the output of the system may determine a value which is of the fixed value resistor divided by the duty cycle of the pulse train effectively controlling the connection of the resistor to ground. One or more additional circuits may be connected in parallel to achieve greater accuracy.
Claims18
An adjustable impedance system comprising:
- a first impedance having a first end and a second end;
- a second impedance having a first end connected to the second end of the first impedance, and having a second end;
- a switch having a first terminal connected to the second end of the second impedance, and having second and third terminals;
- and
- a capacitance having a first terminal connected to the first end of the second impedance and a second terminal connected to the third terminal of the switch;
- and
- wherein:
- the second terminal of the switch is an input for a signal to control a connection between the first and third terminals of the switch;
- to control the connection between the first and third terminals of the switch is to control a third impedance between the first end of the second impedance and the third terminal of the switch, wherein the capacitance is in parallel with the third impedance;
- and
- each of the first and second impedances comprises one or more resistors.
An adjustable impedance system comprising:
- a first impedance having a first end and a second end;
- a second impedance having a first end connected to the second end of the first impedance, and having a second end;
- and
- a switch having a first terminal connected to the second end of the second impedance, and having second and third terminals;
- and
- wherein:
- the second terminal of the switch is an input for a signal to control a connection between the first and third terminals of the switch;
- and
- to control the connection between the first and third terminals of the switch is to control a third impedance between the first end of the second impedance and the third terminal of the switch;
- each of the first and second impedances comprises one or more resistors;
- the switch is a semiconductor;
- the signal comprises a duty cycle;
- a size of the duty cycle determines a magnitude of the third impedance;
- the signal comprises a stream of time slices;
- and
- a number of time slices per period of time effectively determines the size of the duty cycle.
A method of providing a variable resistance, comprising:
- connecting first and second resistances in a series having a first end, a common connection and a second end;
- connecting a first terminal of a switch to the second end of the series;
- connecting the first end of the series to a first voltage terminal;
- connecting a third terminal of the switch to a second voltage terminal, wherein a third resistance is between the common connection and the third terminal of the switch;
- connecting a second terminal of the switch to a signal source for controlling a connection between the first and third terminals of the switch;
- and
- connecting a first terminal of a capacitive element to the common connection and a second terminal of the capacitive element to the third terminal of the switch.
A digital potentiometer system comprising:
- a first resistor having first and second ends;
- a second resistor having a first end connected to the second end of the first resistor, and having a second end;
- a semiconductor having a first terminal connected to the second end of the second resistor, and having second and third terminals;
- and
- a capacitance connected between the first end of the second resistor and the third terminal of the semiconductor;
- and
- wherein:
- the second and third terminals of the semiconductor are for receiving signals having a duty cycle;
- and
- the duty cycle can be modulated to adjust an amount of resistance between the first end of the second resistor and the third terminal of the semiconductor.
Dependencies are inferred from the claim text.