초록 ▼

A circuit apparatus comprises interface circuitry between analog and digital circuitry. A multiple reference circuit provides a variety of reference voltage signals. The multiple reference circuitry is coupled to a selection circuit that selectively couples one of the reference voltage signals to a

A circuit apparatus comprises interface circuitry between analog and digital circuitry. A multiple reference circuit provides a variety of reference voltage signals. The multiple reference circuitry is coupled to a selection circuit that selectively couples one of the reference voltage signals to a first reference input of the interface circuitry and selectively couples another of the reference voltage signals to a second reference input of the interface circuitry, whereby the first and second reference inputs may be selectively coupled to the reference voltages and the circuit maintains a ratiometric relationship between the digital and analog circuitry.

대표청구항 ▼

A circuit apparatus comprising: multiple reference circuit means, coupled to an unregulated voltage supply, for providing multiple reference signals at a variety of voltage levels that vary in relation to variations of the unregulated voltage supply; analog circuitry coupled to the unregulated volta

A circuit apparatus comprising: multiple reference circuit means, coupled to an unregulated voltage supply, for providing multiple reference signals at a variety of voltage levels that vary in relation to variations of the unregulated voltage supply; analog circuitry coupled to the unregulated voltage supply for performing operations that vary in relation to variations of the unregulated voltage supply; digital circuitry having a regulated voltage supply coupled to the unregulated voltage supply for rendering operations performed by the digital circuitry insensitive to variations in the unregulated voltage supply; means for interfacing the digital and analog circuitry, the interfacing means having positive and negative reference inputs and performing conversion between analog and digital signals, the conversion varying in relation to reference voltage levels applied to the positive and negative reference inputs; and select means for coupling the positive reference input of the interfacing means to a first reference signal of the multiple reference circuit means and for coupling the negative reference input of the interfacing means to a second reference signal of the multiple reference circuit means, wherein variations in operations performed by the analog circuitry due to the unregulated voltage supply compensate for variations in the conversion between analog and digital signals due to the unregulated power supply to maintain a ratiometric relationship between the analog and digital circuitry.