Pulse modulated digital to analog converter (DAC)

A device comprising:

• a plurality of resistive elements;
• at least one switch connected to one of said resistive elements;
• a capacitive element connected to said resistive elements thereby forming a low pass filter with said resistive elements;
• and
• a controller connected to said at least one switch, said controller operative to open and close said at least one switch thereby switching the resistance of said low pass filter.

A device comprising:

• a plurality of resistive elements;
• at least one switch connected to one of said resistive elements;
• a capacitive element connected to said resistive elements thereby forming a low pass filter with said resistive elements, said low pass filter having a response time;
• and
• a controller connected to said at least one switch, said controller operative to open and close said at least one switch thereby changing said response time.

A digital to analog converter comprising:

• a digital circuit which produces a pulse modulated signal;
• and
• a switchable low pass filter having a plurality of response times for converting said pulse modulated signal to an analog signal having ripples,
• wherein switching said low pass filter among said response times changes the size of said ripples.

A device for producing a pulse density modulated signal whose pulse timing is jittered, the device comprising:

• a flip flop for storing a value;
• a random number generator for producing a substantially random number;
• and
• an adder for adding said substantially random number and a multi-bit number to said value, said adder having an upper limit,
• wherein a pulse is produced when the sum of said substantially random number, said multi-bit number and said value is not less than said upper limit.

A method for producing a pulse density modulated signal whose pulse timing is jittered, the method comprising the steps of:

• adding a substantially random number and a multi-bit number to a value stored in a flip flop, thereby producing a sum;
• if said sum is less than an upper limit, storing said sum in said flip flop, thereby replacing said value;
• if said sum is not less than said upper limit, producing a pulse;
• subtracting said upper limit from said sum, thereby producing a result;
• and
• storing said result in a flip flop;
• and repeating said steps.