Pulse width modulator with two-way integrator

A pulse width modulator (PWM), comprising:

• a driver coupled to output a first and a subsequent period of a PWM signal in response to an oscillator signal and a duty ratio signal, wherein the first period includes the PWM signal changing between first and second states, and wherein the subsequent period includes the PWM signal changing between first and second states;
• a two-way oscillator, including a first capacitor, coupled to integrate an oscillator current and to generate the oscillator signal, wherein the two-way oscillator integrates the oscillator current during the first period by charging the first capacitor and integrates the oscillator current during the subsequent period by discharging the first capacitor, wherein the driver determines a first period length of the first period and a subsequent period length of the subsequent period by adjusting the PWM signal to the first state in response to the oscillator signal;
• and
• a two-way integrator, including a second capacitor, coupled to integrate an input current and coupled to generate the duty ratio signal, wherein the two-way integrator integrates the input current during the first period by charging the second capacitor and integrates the input current during the subsequent period by discharging the second capacitor, wherein driver determines a first duty ratio of the first period and a subsequent duty ratio of the subsequent period by adjusting the PWM signal to the second state in response to the duty ratio signal.

A two-way integrator, comprising:

• a first input to be coupled to receive an input signal;
• a second input to be coupled to receive a reference signal having a first and a second logic state;
• a first current source coupled to source a first input current that is responsive to the input signal;
• a second current source coupled to sink a second input current that is responsive to the input signal;
• a capacitor coupled to integrate the first input current by charging with the first current source when the reference signal is at the first logic state and coupled to integrate the second input current by discharging with the second current source when the reference signal is at the second logic state;
• a switching reference coupled to receive a pulse signal, wherein the switching reference is adapted to output a first reference voltage responsive to a first pulse of the pulse signal and to output a second reference voltage responsive to a subsequent pulse of the pulse signal;
• and
• a comparator, the comparator having a first input coupled to the switching reference and a second input coupled to the capacitor.