fig1 shows the basic components of the present invention which include : a programmable waveform generator 101 , a digital - to - analog converter ( dac ) 103 , a coupling capacitor 105 , a rectifier and multiplexer circuit 107 , and a filter 109 . fig1 blocks 110a , 110b and 110c , shows that the programmable , negative voltage v o can , for example , be utilized for biasing dual - gate mesfet amplifiers in the transmitter section of a cellular telephone , for biasing the liquid crystal display ( lcd ) of a cellular telephone , and for regulating a voltage controlled amplifier ( vco ) in a dual - band cellular telephone . in a first exemplary embodiment of the present invention , as illustrated in fig2 a microprocessor 201 controls the generation of a sequence of digital signals representing an ac waveform , for example , a square wave having a fundamental frequency of approximately 100 khz . however , one skilled in the art will understand that other ac waveforms may be generated , such as sawtooth waveforms and sinusoidal waveforms . the digital values representing the ac waveform are stored in a memory ( not shown ) associated with the microprocessor 201 . a dac 203 then converts the digital ac waveform to an analog ac waveform . the analog ac waveform is then coupled through a capacitor 205 to a rectifier / multiplier circuit 207 which rectifies the analog ac waveform producing a negative , substantially dc voltage . the coupling capacitor 205 serves as a low to medium pass filter . in the above - identified exemplary embodiment , the rectifier / multiplier circuit 207 is a voltage - doubler comprising a pair of diodes d 1 and d 2 . however , one skilled in the art will also readily understand that other rectifier circuit configurations may be employed to accomplish this task , such as voltage triplers , quadruplers , and full - wave bridges . once rectified and multiplied , the substantially dc voltage encounters a low - pass filter 209 , which is designed to further smooth the substantially dc voltage . this produces a first voltage v b which is a negative dc voltage . a second dac 211 , also operatively connected to the microprocessor 201 , produces a second voltage v a . in the exemplary embodiment , the second voltage v a is a positive dc voltage . the difference between the negative voltage v b and the positive voltage v a is applied across a voltage divider circuit 213 . the voltage divider circuit 213 comprises resistors r 1 and r 2 . the center junction between resistors r 1 and r 2 serves as the output point from which a low - current voltage v o is generated . an advantage of this exemplary embodiment is that the low - current voltage v o , can be varied by programming the microprocessor 201 to modify the positive dc voltage level of v a . although , one skilled in the art will understand that the low - current , voltage v o can also be controlled by varying the amplitude of the ac waveform in lieu of , or in addition to , varying the voltage level of v a . moreover , the voltage level of v a and / or the amplitude of the ac waveform can be adjusted so as to produce either a positive or a negative output voltage v o , wherein a positive voltage output v o can be made to exceed the available supply voltage through the employment of voltage - multiplying rectifier circuits . in a second exemplary alternative embodiment , as illustrated in fig3 the low - current , voltage output v o is regulated by a feedback circuit 315 . the feedback circuit comprises an analog - to - digital converter ( adc ) 317 , which digitizes ( i . e ., samples ) the output voltage v o and supplies the digital values to the microprocessor 301 . the microprocessor 301 then compares the digitized values with a desired output voltage v d . based upon the outcome of this comparison , the microprocessor 301 takes corrective action by adjusting the positive dc voltage level of v a , or in the alternative , by adjusting the amplitude of the ac waveform . fig4 illustrates yet a third exemplary embodiment of the present invention , which operates in a similar manner as the exemplary embodiments depicted in fig2 and 3 , but for the ac waveform used to create v b is independently generated , as illustrated in block 401 . in contrast to the above - described embodiments , the ac waveform associated with v b is not generated by the microprocessor , such as microprocessor 201 in fig2 . rather , the ac waveform is independently generated , for example , by a temperature controlled crystal oscillator ( tcxo ) or a transistor - transistor logic ( ttl ) device , such that the periodic loading of a digitized ac waveform from a microprocessor to a digital - to - analog converter is no longer necessary . therefore , an independently generated analog ac waveform is coupled directly to a rectifier / multiplier circuit , for example , the rectifier / multiplier circuit 407 . in this embodiment , the microprocessor 410 controls the low - current voltage output v o by adjusting the voltage level of v a . fig5 illustrates the method steps of an exemplary control algorithm that may be used to control the output voltage v o in accordance with the exemplary embodiment shown in fig3 . in accordance with fig5 an output voltage v o is generated , as illustrated by step 501 , which is then digitized ( i . e ., sampled ) by the adc 317 , as illustrated by step 503 . each of the digitized values of the output voltage v o is then supplied to the microprocessor 301 which determines the difference between each digitized value and a predefined , desired voltage output value v d . each difference value is then compared to a predefined threshold value e , in accordance with step 505 . if the difference value is less than the predefined threshold e , in accordance with the &# 34 ; yes &# 34 ; path out of decision block 505 , the microprocessor 301 need not take corrective action and another digitized value of the output voltage v 0 is retrieved . if , however , the difference between the sampled output voltage v 0 and the desired output voltage v d is not less than the predefined threshold e , in accordance with the &# 34 ; no &# 34 ; path out of decision block 505 , the microprocessor 301 determines whether the desired output voltage v d is greater than or less than the digitized value of the output voltage v o , according to step 507 . if v d is greater than v o , in accordance with the &# 34 ; yes &# 34 ; path out of decision block 507 , the microprocessor 301 will lower the voltage level of v a , for example , by 5 % as shown in step 509 . if v d is less then v o , in accordance with the &# 34 ; no &# 34 ; path out of decision block 507 , the microprocessor 301 will increase the voltage level of v a , for example by 5 %, as shown in step 511 . again , one skilled in the art will understand that alternative control algorithms may be employed to achieve the same purpose . the present invention has been described with reference to a few exemplary embodiments . however , it will be readily apparent to those skilled in the art that is possible to embody the invention in specific forms other than the exemplary embodiments described above , and that this may be done without departing from the spirit of the invention . the exemplary embodiments described hereinabove are merely illustrative and should not be considered restrictive in any way . the scope of the invention is given by the appended claims , rather than the preceding description , and all variations and equivalents which fall within the range of the claims are intended to be embraced therein .