Matched digital-to-analog converters
AssigneeRambus Inc.
InventorsRavi Shivnaraine, Marcus Van Ierssel
Life of this patent
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Abstract
A voltage ladder is used to generate reference voltages. The voltage ladder is used by multiple digital-to-analog converters (DACs). In particular, the voltage ladder is used by multiple pulse-width modulation (PWM) DACs. Having multiple DACs utilize a common voltage ladder for their reference voltages reduces mismatched output voltages between DACs. Having multiple DACs utilize the common voltage ladder helps ensure that the reference voltages used by different DACs are not affected by process, voltage, and/or temperature variations in the reference voltages that would occur when using different voltage ladders for each DAC.
Claims20
An integrated circuit, comprising:
- a resistive ladder to generate a plurality of reference voltages;
- and,
- a first pulse width modulation stage coupled to the resistive ladder to alternately select between a first selected one of the plurality of reference voltages for a first portion of a clock cycle of a clock signal and a second one of the plurality of reference voltages for a second portion of the clock cycle to produce a first output signal, the second portion of the clock cycle to be a remaining portion of the clock cycle after the first portion of the clock cycle is removed from the clock cycle.
An integrated circuit, comprising:
- a plurality of pulse-width modulation (PWM) digital to analog converters (DACs) sharing a common voltage reference ladder to produce a plurality of reference voltages;
- and,
- the PWM DACs comprising:
- selection circuitry to provide a first selected reference voltage and a second selected reference voltage to PWM selection circuitry, the PWM selection circuitry to select the first selected reference voltage to as a PWM output voltage with a first duty cycle and to select the second selected reference voltage to as the PWM output voltage with a second duty cycle.
A method, comprising:
- selecting a first reference voltage and a second reference voltage from a plurality of reference voltages generated by a resistive ladder that is shared by a plurality of pulse-width modulation digital to analog converters;
- receiving a first clock signal cycling at a clock signal cycle time;
- selecting the first reference voltage to be provided to a pulse-width modulation output node for a first portion of a clock signal cycle time;
- and,
- selecting the second reference voltage to be provided to the pulse-width modulation output node for a second portion of the clock signal cycle time.
Dependencies are inferred from the claim text.