Digital to analog converter (DAC) with ternary or tri-state current source
View Patent ↗Digital to analog converter (DAC) with ternary or tri-state current source. A DAC including a number of ternary or tri-state devices operates based upon codewords provided thereto. Generally, each respective codeword bit directs operation of one of the respective ternary or tri-state devices within the DAC. Each ternary or tri-state device operates in at least three respective operational states (e.g., based upon the respective values of +1, −1, or 0 being provided thereto). In a current source implementation, each respective current source is implemented to deliver current, draw current, or neither delivered or draw current. In a voltage source implementation, each respective voltage source is implemented to provide a positive voltage, a negative voltage, or provide no voltage. A DAC coding table may be designed based upon characterization of codewords provided to one or more DACs (e.g., based upon a distribution, a probability density function (PDF), etc. of such codewords).
1. An apparatus, comprising:
a plurality of digital to analog converters (DACs), wherein:
a first of the plurality of DACs for processing a first number of bits of a codeword thereby generating a first analog signal; and
a second of the plurality of DACs for processing a second number of bits of the codeword thereby generating a second analog signal; and
a combiner for combining the first analog signal and the second analog signal thereby generating a third analog signal; and wherein:
each of the plurality of DACs respectively including a plurality of ternary or tri-state current or voltage sources operative in accordance with a DAC encoding table based on a probability density function (PDF) of a plurality of codewords such that each of the plurality of ternary or tri-state current or voltage sources respectively operative based on one respective bit of the codeword, such that each bit of the codeword respectively having a value of +1, −1, or 0; and
the PDF of the plurality of codewords having an approximately Gaussian distribution.
2. The apparatus of claim 1 , wherein:
the plurality of ternary or tri-state current or voltage sources being a plurality of ternary or tri-state current sources; and
each of the plurality of ternary or tri-state current sources respectively delivering current when the respective bit of the codeword corresponding thereto having a value of +1, drawing current when the respective bit of the codeword corresponding thereto having a value of −1, and being off when the respective bit of the codeword corresponding thereto having a value of 0.
3. The apparatus of claim 1 , wherein:
the plurality of ternary or tri-state current or voltage sources being a plurality of ternary or tri-state voltage sources; and
each of the plurality of ternary or tri-state voltage sources respectively providing a positive voltage when the respective bit of the codeword corresponding thereto having a value of +1, providing a negative voltage when the respective bit of the codeword corresponding thereto having a value of −1, and being off when the respective bit of the codeword corresponding thereto having a value of 0.
4. The apparatus of claim 1 , wherein:
the DAC encoding table implemented such that one of the plurality of ternary or tri-state current or voltage sources corresponding to a most significant bit (MSB) of the codeword operative, statistically, less than a predetermined amount of time during which the device being operational.
5. The apparatus of claim 1 , wherein:
the apparatus being a communication device operative within at least one of a satellite communication system, a wireless communication system, a wired communication system, a fiber-optic communication system, and a mobile communication system.
6. An apparatus, comprising:
a digital to analog converter (DAC) for processing a codeword thereby generating an analog signal, wherein:
the DAC including a plurality of ternary or tri-state current or voltage sources operative in accordance with a DAC encoding table based on a probability density function (PDF) of a plurality of codewords such that each of the plurality of ternary or tri-state current or voltage sources respectively operative based on one respective bit of the codeword, such that each bit of the codeword respectively having a value of +1, −1, or 0.
7. The apparatus of claim 6 , wherein:
the plurality of ternary or tri-state current or voltage sources being a plurality of ternary or tri-state current sources; and
each of the plurality of ternary or tri-state current sources respectively delivering current when the respective bit of the codeword corresponding thereto having a value of +1, drawing current when the respective bit of the codeword corresponding thereto having a value of −1, and being off when the respective bit of the codeword corresponding thereto having a value of 0.
8. The apparatus of claim 6 , wherein:
the plurality of ternary or tri-state current or voltage sources being a plurality of ternary or tri-state voltage sources; and
each of the plurality of ternary or tri-state voltage sources respectively providing a positive voltage when the respective bit of the codeword corresponding thereto having a value of +1, providing a negative voltage when the respective bit of the codeword corresponding thereto having a value of −1, and being off when the respective bit of the codeword corresponding thereto having a value of 0.
9. The apparatus of claim 6 , wherein:
the DAC including a plurality of DACs;
a first of the plurality of DACs operative in accordance with a first subset of bits of the codeword generating a first analog signal; and
a second of the plurality of DACs operative in accordance with a second subset of bits of the codeword generating a second analog signal; and further comprising:
a combiner for combining the first analog signal and the second analog signal thereby generating the analog signal.
10. The apparatus of claim 9 , wherein:
the first subset of bits of the codeword including a first number of bits; and
the second subset of bits of the codeword including a second number of bits.
11. The apparatus of claim 6 , wherein:
the PDF of the plurality of codewords having an approximately Gaussian distribution.
12. The apparatus of claim 6 , wherein:
the DAC encoding table implemented such that one of the plurality of ternary or tri-state current or voltage sources corresponding to a most significant bit (MSB) of the codeword operative, statistically, less than a predetermined amount of time during which the device being operational.
13. The apparatus of claim 6 , wherein:
the apparatus being a communication device operative within at least one of a satellite communication system, a wireless communication system, a wired communication system, a fiber-optic communication system, and a mobile communication system.
14. A method for operating a device including a digital to analog converter (DAC), the method comprising:
operating a digital to analog converter (DAC) for processing a codeword thereby generating an analog signal, wherein the DAC including a plurality of ternary or tri-state current or voltage sources operative in accordance with a DAC encoding table based on a probability density function (PDF) of a plurality of codewords such that each of the plurality of ternary or tri-state current or voltage sources respectively operative based on one respective bit of the codeword, such that each bit of the codeword respectively having a value of +1, −1, or 0.
15. The method of claim 14 , wherein:
the plurality of ternary or tri-state current or voltage sources being a plurality of ternary or tri-state current sources; and
each of the plurality of ternary or tri-state current sources respectively delivering current when the respective bit of the codeword corresponding thereto having a value of +1, drawing current when the respective bit of the codeword corresponding thereto having a value of −1, and being off when the respective bit of the codeword corresponding thereto having a value of 0.
16. The method of claim 14 , wherein:
the plurality of ternary or tri-state current or voltage sources being a plurality of ternary or tri-state voltage sources; and
each of the plurality of ternary or tri-state voltage sources respectively providing a positive voltage when the respective bit of the codeword corresponding thereto having a value of +1, providing a negative voltage when the respective bit of the codeword corresponding thereto having a value of −1, and being off when the respective bit of the codeword corresponding thereto having a value of 0.
17. The method of claim 14 , wherein:
the DAC including a plurality of DACs; and further comprising:
operating a first of the plurality of DACs in accordance with a first subset of bits of the codeword generating a first analog signal; and
operating a second of the plurality of DACs in accordance with a second subset of bits of the codeword generating a second analog signal; and
combining the first analog signal and the second analog signal thereby generating the analog signal.
18. The method of claim 17 , wherein:
the first subset of bits of the codeword including a first number of bits; and
the second subset of bits of the codeword including a second number of bits.
19. The method of claim 14 , wherein:
the PDF of the plurality of codewords having an approximately Gaussian distribution.
20. The method of claim 14 , wherein:
the DAC encoding table implemented such that one of the plurality of ternary or tri-state current or voltage sources corresponding to a most significant bit (MSB) of the codeword operative, statistically, less than a predetermined amount of time during which the device being operational.
21. The method of claim 14 , wherein:
the device being a communication device operative within at least one of a satellite communication system, a wireless communication system, a wired communication system, a fiber-optic communication system, and a mobile communication system.