Digital-to-analog converter having programmable transfer function errors and method of programming same

A digital-to-analog converter with programmable transfer function errors for providing accuracy and resolution improvements, comprising:

• first current-steering converter means responsive to first digital data signals and having predetermined transfer function errors,
• second current-steering converter means responsive to second digital data signals and having transfer function errors less than implied by the combined resolution of said first and said second digital data signals,
• third current-steering converter means responsive to third digital data signals and having transfer function errors of less than those of said second current-steering converter means,
• memorizing means for said third digital data signals,
• resistive means, having a predetermined number of terminals connected to the outputs of said first, said second and said third current-steering converter means and providing a digital-to-analog voltage output between two of said number of terminals,
• calibration means determining said third digital data signals in a manner to program the transfer function of said first current-steering converter means for the purpose of reducing transfer function errors of said digital-to-analog converter voltage output to less than implied by the combined resolution of said first and second digital data signals,
• digital data signal control means operatively controlling said first and said second current-steering converter means in response to said first and said second digital data signals and further operatively controlling said third current-steering converter means by selectively accessing said memorizing means for said third digital data signals.

A Digital-to-Analog Converter with programmable transfer function errors having a digital data input signal, the Converter comprising:

• a Main-Converter receiving a digital data input signal and producing an output current responding to said digital data input signal, the Main-Converter output current having a first range at a first resolution with predetermined transfer function errors;
• a predetermined number of Sub-Converters each responding to one of a predetermined number of computed digital signals and each Sub-Converter producing output currents in response to said computed digital signals, the output current of each Sub-Converter having a range smaller than said first range at a resolution finer than said first resolution with transfer function errors smaller than implied by said first resolution;
• a resistor network having input terminals connected to receive the Main-Converter output current and any Sub-Converter output currrent and having two output terminals;
• and
• a Calibration circuit connected to the output terminals of the Resistor Network and connected to the digital data input signal and providing the computed digital signals for each Sub-Converter.