Patent ID: 6853227
Filing Date: 2005-02-08
Classification: H03K

Abstract:
1. A pulse width controller circuit for generating a periodic digital output signal, the controller circuit comprising: a voltage controlled current source, said voltage controlled current source further comprising a PMOSFET connected to shut off said current source; a timing capacitor connected to said current source; a reset switch circuit, said switch circuit connected in parallel with said timing capacitor and driven by an input clock signal; an invert gate serving as a detector, the input of said invert gate connected to said current source and said timing capacitor; a low pass filter circuit connected to the output of said invert gate; and an integrator circuit having an inverting input connected to said low pass filter, a non-inverting input connected to an external ratio control voltage source, and an output connected to and providing the control voltage for said voltage controlled current source, wherein said integrator circuit operates as a servo control amplifier such that its output will adjust the duty cycle of the waveform appearing at the output of said invert gate so that its average value is substantially equal to said external ratio control voltage.