Digital to analog converter

A digital to analog converter, comprising:

• a multi-bit counter;
• a first plurality of AND logic gates coupled to the multi-bit counter;
• a second plurality of AND logic gates coupled to the multi-bit counter;
• a digital input selectively coupled to the first and second plurality of AND logic gates;
• a first OR logic gate coupled to an output of the first plurality of AND logic gates;
• a second OR logic gate coupled to an output of the second plurality of AND logic gates;
• a first AND logic gate coupled to an output of the first OR logic gate;
• a second AND logic gate coupled to an output of the second OR logic gate;
• a clock coupled to an input of the first and second AND logic gates and an input of the multi-bit counter;
• a filter coupled to an output of the first and second AND logic gates;
• and
• an analog output coupled to the filter, wherein the analog output is based on the digital input.

A method of converting a multi-bit digital input signal to an analog signal, the method comprising:

• receiving a digital number;
• converting the digital number to a series of pulses;
• summing the series of pulses, wherein the pulses in a predetermined period represents the received digital number;
• and
• applying a clock signal to the sum of the series of pulses to obtain an analog signal that represents the digital number.

A digital to analog converter, comprising:

• a multi-bit counter;
• a plurality of logic circuits coupled to the multi-bit counter;
• a digital input selectively coupled to the plurality of logic circuits;
• a plurality of AND gates, each AND gate coupled to an output of one of the plurality of logic circuits;
• a clock signal coupled to an input of each of the plurality of AND gates;
• and
• a filter coupled to an output of each of the plurality of AND gates, wherein the filter includes an output for an analog signal based on the digital input.

A multi-bit digital to analog converter, comprising:

• a multi-bit counter;
• a clock coupled to an input of the multi-bit counter;
• an inverter coupled to an output of the multi-bit counter;
• a first and a second parallel-in, serial-out shift register each coupled to an output of the multi-bit counter;
• a digital input selectively coupled to the first and second shift registers;
• a first clock inverter coupled to an output of the clock;
• a second clock inverter coupled to an output of the clock;
• a first AND gate coupled to an output of the first clock inverter and an output of the first shift register;
• a second AND gate coupled to an output of the second clock inverter and the second shift register;
• a first resistor coupled to an output of the first AND gate;
• a second resistor coupled to an output of the second AND gate;
• wherein the first and second resistors are coupled to an analog output that is based on the digital input.

A method of testing a multi-bit digital to analog converter, the method comprising:

• generating an 8-bit digital number using the four most significant bits and four least significant bits of an analog to digital converter output;
• applying the four most significant bits to a plurality of inputs of a first 16-bit parallel-in, serial-out shift register;
• applying the four least significant bits to a plurality of inputs of a second 16-bit parallel-in, serial-out shift register;
• converting the four most significant bits to a first series of pulses;
• converting the four least significant bits to a second series of pulses;
• summing the first series of pulses, wherein the first series of pulses represents the digital equivalent of the 4 most significant bits received;
• summing the second series of pulses, wherein the second series of pulses represents the digital equivalent of the 4 least significant bits received;
• applying a clock signal to the sum of the first series of pulses to obtain an first analog signal that represents the digital equivalent of the 4 most significant bits;
• applying the clock signal to the sum of the second series of pulses to obtain a second analog signal that represents the digital equivalent of the 4 least significant bits;
• combining the first and second analog signals so as to produce a third analog signal that represents the 8-bit digital number;
• and
• comparing the third analog output to an output of an 8-bit digital to analog converter.