Pulse width modulator

Abstract

In accordance with some embodiments, a pulse width modulator having a comparator with an applied adjustable waveform to generate a bit stream with a controllably adjustable duty cycle is provided.

1 . A circuit, comprising:
 a pulse width modulator comprising:
 a comparator having an associated reference level, and 
 an adjustable waveform generator coupled to said comparator to provide it with a periodic waveform, the comparator to generate a bit stream having a controllably adjustable duty cycle corresponding to adjustment of the position of the periodic waveform. 
   
   
   
       2 . The circuit of  claim 1 , in which the periodic waveform comprises a triangle wave. 
   
   
       3 . The circuit of  claim 2 , in which the adjustable waveform generator comprises a control to adjust the offset of the periodic waveform, relative to the reference level, in order to adjust said duty cycle. 
   
   
       4 . The circuit of  claim 3 , in which the adjustable waveform generator comprises a dual rail generator coupled to a triangle waveform generator to generate said adjustable periodic waveform. 
   
   
       5 . The circuit of  claim 4 , in which the comparator comprises an inverter, the associated reference level corresponding to the trip point of the inverter. 
   
   
       6 . The circuit of  claim 5 , in which the dual rail generator comprises at least one inverter configured to function as an analog amplifier, said at least one inverter having a trip point substantially the same as the inverter of the comparator. 
   
   
       7 . The circuit of  claim 1 , in which the comparator's associated reference level is defined by a voltage reference coupled to an input of the comparator. 
   
   
       8 . A voltage regulator comprising at least one pulse width modulator as defined in  claim 1 . 
   
   
       9 . A method, comprising:
 comparing a periodic waveform against a fixed reference to generate a bit stream having a controllably variable duty cycle; and   providing a control to adjust the periodic waveform relative to the fixed reference level in order to adjust the duty cycle.   
   
   
       10 . The method of  claim 9 , in which the periodic waveform comprises a triangular wave form. 
   
   
       11 . The method of  claim 10 , further comprising generating the triangular waveform using a dual rail generator. 
   
   
       12 . The method of  claim 1  in which providing a control to adjust the waveform comprises providing an offset control to adjust the offset of the waveform relative to the fixed reference. 
   
   
       13 . The method of  claim 9 , in which the fixed reference is coupled to a comparator to compare the waveform against the fixed reference. 
   
   
       14 . The method of  claim 9 , in which comparing comprises comparing the waveform using an inverter to compare the waveform against the trip point of the inverter. 
   
   
       15 . A computer system, comprising:
 a microprocessor;   a voltage regulator coupled to the microprocessor to provide it with a regulated voltage supply, the voltage regulator comprising at least one a pulse width modulator comprising: a comparator having an associated reference level, and an adjustable waveform generator coupled to said comparator to provide it with a periodic waveform, the comparator to generate a bit stream having a controllably adjustable duty cycle corresponding to adjustment of the position of the periodic waveform; and   a power supply coupled to the voltage regulator to provide it with power to generate the regulated voltage supply.   
   
   
       16 . The system of  claim 15 , in which the power supply comprises a re-chargeable battery. 
   
   
       17 . The system of  claim 15 , in which the periodic waveform comprises a triangle wave. 
   
   
       18 . The system of  claim 17 , in which the adjustable waveform generator comprises a control to adjust the offset of the periodic waveform, relative to the reference level, in order to adjust said duty cycle. 
   
   
       19 . The system of  claim 18 , in which the adjustable waveform generator comprises a dual rail generator coupled to a triangle waveform generator to generate said adjustable periodic waveform. 
   
   
       20 . The system of  claim 19 , in which the comparator comprises an inverter, the associated reference level corresponding to the trip point of the inverter.