METHOD AND APPARATUS FOR DC-TO-DC CONVERSION
A direct current-to-direct current (‘DC-DC’) converter generates a pulse-width modulated (‘PWM’) control signal, and generates an output voltage from an input voltage as a function of a duty cycle of the PWM control signal. A feed-forward module controls both the duty cycle and a repetition rate of the PWM control signal as regressive functions of the input voltage so as to tend to compensate for variation in the input voltage.
1 . A direct current-to-direct current (‘DC-DC’) converter, comprising:
a control signal generator for generating a pulse-width modulated (‘PWM’) control signal; and
an output voltage generator for generating an output voltage from an input voltage as a function of a duty cycle of said PWM control signal,
wherein said control signal generator comprises a feed-forward module for controlling both said duty cycle and a repetition rate of said PWM control signal as regressive functions of said input voltage to compensate for variation in said input voltage.
2 . The DC-DC converter of claim 1 , wherein said feed-forward module comprises a periodic signal generator for generating a periodic signal whose amplitude is a progressive function of said input voltage and whose repetition rate is a regressive function of said input voltage, and a comparator for comparing said periodic signal with a reference signal and producing a comparator output for controlling said duty cycle to compensate for variation in said input voltage.
3 . The DC-DC converter of claim 2 , wherein said periodic signal generator comprises a saw-tooth signal generator for generating said periodic signal as a saw-tooth signal whose peak value is a progressive function of said input voltage.
4 . The DC-DC converter of claim 3 , wherein said saw-tooth signal generator comprises a capacitor, a current source that is a progressive function of said input voltage for charging said capacitor, and a path for periodically discharging said capacitor.
5 . The DC-DC converter of claim 2 , wherein said periodic signal generator comprises an oscillator whose repetition rate is a regressive function of said input voltage for controlling said repetition rate of said periodic signal.
6 . The DC-DC converter of claim 2 , wherein said control signal generator includes a feedback module for generating said reference signal as a function of said output voltage to compensate for variation in said output voltage.
7 . The DC-DC converter of claim 6 , wherein a relationship between said duty cycle and said input voltage is of the form:
d
=
Q
+
P
V
in
+
K
and
Q
=
-
α
V
err
,
P
=
α
V
err
K
+
V
err
M
where d is said duty cycle, V in is said input voltage, V err is said reference signal and α, K and M are independent of said input voltage, said duty cycle and said output voltage.
8 . A direct current-to-direct current (‘DC-DC’) converter, comprising:
a control signal generator for generating a pulse-width modulated (‘PWM’) control signal; and
an output voltage generator for generating an output voltage from an input voltage as a function of a duty cycle of the PWM control signal,
wherein the control signal generator comprises,
a feed-forward module for controlling both the duty cycle and a repetition rate of the PWM control signal as regressive functions of the input voltage to compensate for variation in the input voltage,
wherein the feed-forward module comprises a periodic signal generator for generating a periodic signal whose amplitude is a progressive function of the input voltage and whose repetition rate is a regressive function of the input voltage, and a comparator for comparing the periodic signal with a reference signal and producing a comparator output for controlling the duty cycle to compensate for variation in the input voltage, and
wherein the periodic signal generator comprises a saw-tooth signal generator for generating the periodic signal as a saw-tooth signal whose peak value is a progressive function of the input voltage.
9 . The DC-DC converter of claim 8 , wherein said saw-tooth signal generator comprises a capacitor, a current source that is a progressive function of said input voltage for charging said capacitor, and a path for periodically discharging said capacitor.
10 . The DC-DC converter of claim 8 , wherein said periodic signal generator comprises an oscillator whose repetition rate is a regressive function of said input voltage for controlling said repetition rate of said periodic signal.
11 . A method of direct current-to-direct current (‘DC-DC’) conversion, comprising:
generating a pulse-width modulated (‘PWM’) control signal;
generating an output voltage from an input voltage as a function of a duty cycle of said PWM control signal; and
controlling both said duty cycle and a repetition rate of said PWM control signal using feed-forward control as regressive functions of said input voltage to compensate for variation in said input voltage.
12 . The DC-DC conversion method of claim 11 , wherein generating said PWM control signal includes generating a periodic signal whose amplitude is a progressive function of said input voltage and whose repetition rate is a regressive function of said input voltage, and controlling said duty cycle includes comparing said periodic signal with a reference signal to compensate for variation in said input voltage.
13 . The DC-DC conversion method of claim 12 , wherein said periodic signal is a saw-tooth signal whose peak value is a progressive function of said input voltage.
14 . The DC-DC conversion method of claim 13 , wherein generating said saw-tooth signal comprises charging a capacitor using a current that is a progressive function of said input voltage, and periodically discharging said capacitor.
15 . The DC-DC conversion method of claim 12 , wherein generating said periodic signal includes using an oscillator to generate a signal whose frequency is a regressive function of said input voltage for controlling said repetition rate of said periodic signal.
16 . The DC-DC conversion method of claim 12 , wherein the reference signal is generated using feedback control as a function of said output voltage to compensate for variation in said output voltage.
17 . The DC-DC conversion method of claim 16 , wherein a relationship between said duty cycle and said input voltage is of the form:
d
=
Q
+
P
V
in
+
K
and
Q
=
-
α
V
err
,
P
=
α
V
err
K
+
V
err
M
where d is said duty cycle, V IN is said input voltage, V err is said reference signal and α, K and M are independent of said input voltage, said duty cycle and said output voltage.