Adaptive slope generator

1. An adaptive slope generator comprising:

a current mirror configured to:

receive a multiplied current that varies as a function of an output voltage and a switching frequency of a switching current, wherein the output voltage characterizes the switching current provided to a load coupled to an inductor;

receive an oscillation current, wherein the oscillation current has an amplitude that corresponds to the switching frequency of the switching current;

generate an output current substantially equivalent to the product of the oscillation current and the output voltage; and

a ramp generator configured to generate a slope compensation signal based on the output current, the slope compensation signal having a sawtooth shape and a slope that varies as a function of the output voltage.

2. The adaptive slope generator of claim 1 , wherein the ramp generator further comprises a slope compensation capacitor, wherein the slope of the slope compensation signal also varies as a function of a capacitance of the slope compensation capacitor.

3. The adaptive slope generator of claim 2 , wherein:

m s =V OUT ·K R ·I OSC /C

wherein:

m s is the slope of the slope compensation signal;

V out is the output voltage;

K R is a circuit parameter with a range of about 1 to about 1000;

I OSC is the oscillation current; and

C is the capacitance of the slope compensation capacitor.

4. The adaptive slope generator of claim 2 , wherein the ramp generator further comprises a current mirror having a transfer ratio, wherein the slope of the slope compensation signal also varies as a function of the transfer ratio of the current mirror.

5. The adaptive slope generator of claim 4 , wherein the ramp generator further comprises an offset current configured to set a minimum slope of the slope compensation signal.

6. The adaptive slope generator of claim 1 , further comprising a translinear multiplier configured to:

receive a first current that varies as a function of the output voltage;

receive the oscillation current;

receive a reference current that comprises a current that varies based on a reference voltage and a given reference resistor; and

generate the multiplied current, the multiplied current being substantially equal to a product of the output voltage and the oscillation current minus the oscillation current.

7. The adaptive slope generator of claim 6 , further comprising an error compensated voltage to current (V-I) converter configured to generate the first current that characterizes a difference of the output voltage and the reference voltage divided by a resistance of another reference resistor.

8. The adaptive slope generator of claim 7 , wherein the given reference resistor and the another reference resistor have substantially equal resistances.

9. The adaptive slope generator of claim 8 , wherein the reference voltage is about 1 volt (V).

10. The adaptive slope generator of claim 1 comprising a plurality of field effect transistors (FETs).

11. The adaptive slope generator of claim 10 , wherein each of the FETs is configured to operate in saturation mode.

12. The adaptive slope generator of claim 1 , wherein the adaptive slope generator is configured in the absence of a bipolar junction transistor (BJT).

13. An integrated circuit (IC) chip comprising the adaptive slope generator of claim 1 .

14. The IC chip of claim 13 , further comprising:

a controller configured to:

provide a control signal to a switch to control the switching current provided to the load; and

adjust a slope of the switching current based on the slope compensation signal.

15. An adaptive slope generator comprising:

a ramp generator configured to:

receive a clock signal;

receive an output current that characterizes a product of an output voltage and an oscillation current; and

generate a slope compensation signal having a sawtooth shape and a slope that varies as a function of the output voltage and a capacitance of a slope compensation capacitor;

wherein the output voltage corresponds to voltage at a load coupled to an inductor;

wherein the oscillation current has an amplitude corresponding to a switching frequency of a switching current provided to the load.

16. The adaptive slope generator of claim 15 further comprising:

a reference voltage to current (V-I) converter configured to generate a reference current based on a reference voltage;

a translinear multiplier configured to:

receive a first current from an error compensated V-I converter that varies as a function of the output voltage;

receive the oscillation current from an oscillator; and

receive the reference current from the reference V-I converter; and

generate a multiplied current, wherein:

I

MULT

=

I

1

*

I

OSC

I

REF

;

wherein:

I MULT is the multiplied current;

I 1 is the first current;

I OSC is the oscillation current; and

I REF is the reference current.

17. The adaptive slope generator of claim 15 , wherein:

m

s

=

V

OUT

*

K

R

*

I

OSC

C

wherein:

m s is the slope of the slope compensation signal;

V out is the output voltage;

K R is a circuit parameter with a range of about 1 to about 1000;

C is the capacitance of the slope compensation capacitor.

18. The adaptive slope generator of claim 15 , wherein the ramp generator further comprises a current mirror having a transfer ratio, wherein the slope of the slope compensation signal also varies as a function of the transfer ratio of the current mirror.

19. The adaptive slope generator of claim 18 , wherein the ramp generator further comprises an offset current configured to set a minimum slope of the slope compensation signal.

20. An integrated circuit (IC) chip comprising:

an error compensated voltage to current (V-I) converter configured to output a first current that characterizes an output voltage, wherein the output voltage characterizes a switching current provided to a load coupled to an inductor;

an oscillator configured to provide an oscillation current that has an amplitude that corresponds to a switching frequency of the switching current;

a reference V-I converter configured to generate a reference current based on a reference voltage;

a translinear multiplier configured to:

generate a multiplied current, the multiplied current being substantially equal to a product of the output voltage and the oscillation current minus the oscillation current;

a current mirror configured to:

generate an output current substantially equivalent to the product of the oscillation current and the output voltage; and

a ramp generator configured to generate a slope compensation signal having a sawtooth shape and a slope that varies as a function of the output voltage, wherein the slope of the switching current is based on the slope compensation signal.