Digital-to-analog converter

A digital to analog converter for converting a time variant digital input signal into a time variant analog signal, comprising:

• an input port for receiving an input data signal, the input data signal being composed of a plurality of bits, a first group of which represents a mantissa value and a second group of which represents both the number of bits in the first group and an exponent value;
• decoder means, coupled to the input port, for receiving a portion of the input signal and generating a first data signal representing the number of bits in the first group and a second data signal representing the exponent value;
• a mantissa digital-to-analog converter, coupled to receive the first group of bits, the mantissa digital-to-analog converter including a number of bit stages which are connected together in a weighted sum fashion so as to produce an analog signal composed of a plurality of differently weighted signal levels, wherein the signal levels are either less than, greater than or equal to a preselected zero level and wherein the bit stages are adapted to operatively respond to the first group of bits to produce therefrom a first analog signal whose amplitude represents the mantissa value, and wherein the mantissa digital-to-analog converter further includes a neutralizing means, which is responsive to the second data signal, for selectively neutralizing one or more of the less signficant bit stages in the mantissa digital-to-analog converter such that the neutralized bit stages will not contribute non-zero signal levels to the first analog signal;
• and
• an exponent multiplier means, coupled to the decoder means and the mantissa digital-to-analog converter, for multiplying the first analog signal by the exponent value represented by the second data signal to produce a second analog signal.

A digital to analog converter comprising:

• an output terminal;
• an R-2R ladder network having a series of R-2R bit stages arranged in order of significance from a least significant end of the network to a most significant end of the network, the most significant end being connected to the output terminal;
• a voltage supply means for supplying a first voltage to the R-2R ladder network, the magnitude of the first voltage relative to a ground level being representative of a full range of discrete output voltage levels than can be generated at the output terminal;
• a biasing means, connected to the least significant end of the network, for generating a bias voltage thereat which is less than the first voltage and greater than the ground level;
• and
• a plurality of switching means for applying either the first voltage or the ground level to respective 2R elements of the R-2R ladder network, wherein at least one of the switching means is adapted to also apply an intermediate voltage, between the first voltage and the ground level, to a respective one of the 2R elements.

A digital-to-analog converter for converting digital input data into an analog output signal, where the digital input data is composed of an a mantissa part and has an exponent value, the exponent value representing a magnitude range and the mantissa part representing a magnitude within the magnitude range, comprising:

• (a) detector means responsive to the digital input data for detecting the magnitude range thereof, said detector means outputting a detection signal representative of the magnitude range of said digital input data;
• (b) digital-to-analog converting means of a predetermined number of bit stages, responsive to said detection signal for converting the mantissa part of said digital input data into an intermediate analog signal, the bit stages being adapted to operatively respond to the mantissa part of the digital input data;
• (c) analog shift means responsive to said detection signal for shifting said intermediate analog signal by an amount corresponding to the magnitude range of said digital input data, said analog shift means outputting said shifted analog signal as the analog output signal;
• and
• (d) control means responsive to said detection signal for changing the number of operative bit stages of said digital-to-analog converting means, said control means decreasing the number of operative bit stages of said digital-to-analog converting means with a decrease of the magnitude range of said digital input data.

A digital-to-analog converter for converting digital input data into an analog output signal, where the digital input data is composed of a number of bits and includes size information representing an exponent value and a bit length number, the bit length number being the number of bits in a variable length mantissa part of the digital input signal, comprising:

• (a) detector means, responsive to the size information of the digital input data, for outputting a detection signal representative of the exponent value of said digital input data;
• (b) digital-to-analog converting means of a predetermined number of bit stages, responsive to said detection signal, for converting the mantissa part of said digital input data into an intermediate analog signal, the bit stages being adapted to operatively respond to the mantissa part bits of the digital input data;
• (c) analog shift means, responsive to said detection signal, for shifting said intermediate analog signal by an amount corresponding to the exponent value of said digital input data, said analog shift means outputting said shifted analog signal as the analog output signal;
• and
• (d) control means, responsive to said detection signal, for changing the number of operative bit stages of said digital-to-analog converting means, said control means decreasing the number of operative bit stages of said digital-to-analog converting means with a decrease of the exponent value of said digital input data.