Piecewise linear digital to analog conversion
AssigneeTexas Instruments Incorporated
InventorMark A. Burns
Life of this patent
Estimating the term…
Abstract
A digital to analog converter includes a network of impedance components having a plurality of nodes having associated voltages. A tap is coupled to one or more associated one of the plurality of nodes to source or sink electrical current relative to the associated node(s). A switching system is operative to couple a selected one of the nodes to an output according to a digital input word and thereby provide an analog voltage corresponding to the digital input.
Claims30
A digital to analog converter, comprising:
- a series network of impedance components comprising at least one resistor, the series network being divided into segments of n resistors, where n is a positive integer;
- a plurality of nodes associated with digital input words connecting adjacent impedance components;
- a tap coupled to an associated node of the plurality of nodes and operative to one of source and sink electrical current relative to the associated node;
- a switching system operative to couple a selected one of the nodes to an output according to a digital input word, and
- a plurality of taps each coupled to an associated breakpoint node that interconnects an adjacent pair of resistor segments so as to one of source and sink electrical current relative to the breakpoint node to which the tap is coupled.
A digital to analog converter, comprising:
- a resistor string comprising a plurality of resistors connected in series between first and second reference voltages, the resistor string including nodes between adjacent of the plurality of resistors associated with digital input words;
- at least one resistive tap coupled to at least one associated node of the resistor string and to a third reference voltage so as to provide a desired breakpoint voltage at the at least one associated node;
- and
- at least one multiplexer operative to couple a selected node of the resistor string to an output based on a value of a digital input word.
A method for making a digital to analog converter (DAC), comprising:
- determining desired non-linear transfer characteristics of the DAC;
- determining a number of breakpoints for approximating the desired transfer characteristics;
- and
- determining breakpoint voltages for each of the breakpoints.
A method for testing operating characteristics of a digital to analog converter (DAC) comprising a plurality of resistors connected in series between first and second reference voltages with nodes between adjacent resistors, at least one tap being coupled to an associated node to source or sink current relative to the associated node, a switch being coupled to a test node for, when activated, supplying a higher than normal test voltage at the test node, the method comprising:
- activating the switch;
- supplying the test voltage to the test node;
- applying digital input words for the DAC up to a word associated with the test node;
- and
- measuring an output voltage of the DAC in response to the application of digital words.
A digital to analog converter (DAC), comprising:
- a series network of impedance components, a plurality of nodes associated with digital input words connecting adjacent impedance components;
- One or more breakpoint circuits each of which is associated with a breakpoint node of the plurality of nodes, the total number of breakpoint nodes fewer than the total number of nodes in the plurality of nodes, each breakpoint node operative to one of source and sink electrical current relative to the associated node such that the desired non-linear transfer characteristics of the DAC can be approximated by selection of breakpoint voltages;
- and
- a switching system operative to couple a selected one of the nodes to an output according to a digital input word.
Dependencies are inferred from the claim text.