Cancellation of regulator output filter poles by second derivative feedback and error amplifier compensation

Claim 2

In the method of regulating a power supply driving a load of value R ohms, which power supply incorporates a series choke of value L henries and a parallel output capacitor of value C farads (and having an effective series resistance of r ohms) in an output filter having a damping factor, which method includes the step of feeding back a selected multiple "a" of the output voltage appearing across the output capacitor to a control circuit for comparison with a reference voltage and responsive correction, which control circuit includes an error amplifier, the improvement wherein: (A) there is also fed back to the control circuit the first derivative of the output voltage in the multiple "b"; (B) there is also fed back to the control circuit the second derivative of the output voltage in the multiple "c"; (C) the frequency/gain characteristic of the error amplifier is adjusted to be flat above a predetermined crossover frequency; and (D) the ratios among "a", "b" and "c" are selected to eliminate the factors contributed by the output filter from the power supply characteristic equation.

Claim 3

The method of claim 1 in which the frequency/gain characteristic of the error amplifier is adjusted to be decreasing-gain-with-increasing-frequency below the crossover frequency.

Claim 4

In the method of regulating a power supply driving a load of value R ohms, which power supply incorporates a series choke of value L henries and a parallel output capacitor of value C farads (and having an effective series resistance of rohms) in an output filter having a damping factor, which method includes the step of feeding back a selected multiple "a" of the output voltage appearing across the output capacitor to a control circuit for comparison with a reference voltage and responsive correction, which control circuit includes an error amplifier, the improvement wherein: (A) there is also fed back to the control circuit the first derivative of the output voltage in the multiple "b" in which: b=(L/R)+Cr; (B) there is also fed back to the control circuit the second derivative of the output voltage in the multiple "c" in which: c=LC(R+r)/R; (C) the error amplifier has: (1) a crossover frequency Ω 3 in radians per second; (2) an input impedance of value R 1 ohms; and (3) a feedback loop including a feedback resistor of value R 2 ohms disposed in series with a first feedback capacitor of value C 1 farads, the feedback loop further including a second feedback capacitor of value C 2 farads, the second feedback capacitor being disposed in parallel with the feedback resistor; and wherein the value relationship among the components is given by: (D) Ω.sub.3 =(C.sub.2 R.sub.2 +C.sub.1 R.sub.2)/R.sub.1 C.sub.1 and (E) C.sub.2 R.sub.2 =rC.

Claim 5

In the method of regulating a power supply driving a load of value R ohms, which power supply incorporates a series choke of value L henries and a parallel output capacitor of value C farads (and having an effective series resistance of rohms) in an output filter having a damping factor, which method includes the step of feeding back a selected multiple "a" of the output voltage appearing across the output capacitor to a control circuit for comparison with a reference voltage and responsive correction, which control circuit includes an error amplifier, the improvement wherein: (A) there is also fed back to the control circuit the first derivative of the output voltage in the multiple "b" in which: b=(L/R)+Cr; (B) there is also fed back to the control circuit the second derivative of the output voltage in the multiple "c" in which: c=LC(R+r)/R; (C) the error amplifier has: (1) a crossover frequency Ω 3 in radians per second; (2) an input impedance of value R 1 ohms; and (3) a feedback loop including a feedback resistor of value R 2 ohms disposed in series with a first feedback capacitor of value C 1 farads, the feedback loop further including a second feedback capacitor of value C 2 farads, the second feedback capacitor being disposed in parallel with the feedback resistor; and wherein the value relationship among the components is given by: (D) Ω.sub.3 =(C.sub.2 R.sub.2 +C.sub.1 R.sub.2)/R.sub.1 C.sub.1 and (E) C.sub.2 R.sub.2 =rC.

Claim 6

The method of claim 3 in which the relationship among the components is further defined by: R 1 C 1 >(C 1 +C 2 )R 2 .

Claim 7

In a regulated power supply driving a load of value R ohms, incorporating a series choke of value L henries and a parallel output capacitor of value C farads (and having an effective series resistance of r ohms) in an output filter and which includes zero derivative means for feeding back a selected multiple "a" of the output voltage appearing across said output capacitor to a control circuit, said control circuit including an error amplifier, for comparison with a reference voltage and responsive correction, the improvement wherein said regulated power supply further includes: (A) first derivative feedback means adapted to feed back to said control circuit the first derivative of the output voltage in the multiple "b" in which: b=(L/R)+Cr; and (B) second derivative feedback means adapted to feed back to said control circuit the second derivative of the output voltage in the multiple "c" in which: c=LC(R+r)/R; (C) said error amplifier is characterized by: (1) a crossover frequency Ω 3 in radians per second; (2) an input impedance of value R 1 ohms; and (3) feedback loop comprising a feedback resistor of value R 2 ohms disposed in series with a first feedback capacitor of value C 1 farads, said feedback loop further comprising a second feedback capacitor of value C 2 farads, said second feedback capacitor being disposed in parallel with said feedback resistor; and wherein the value relationship among the components is given by: (D) Ω.sub.3 =(C.sub.2 R.sub.2 +C.sub.1 R.sub.2)/R.sub.1 C.sub.1 and (E) C.sub.2 R.sub.2 =rC.

Claim 8

In a regulated power supply driving a load of value R ohms, incorporating a series choke of value L henries and a parallel output capacitor of value C farads (and having an effective series resistance of r ohms) in an output filter and which includes zero derivative means for feeding back a selected multiple "a" of the output voltage appearing across said output capacitor to a control circuit, said control circuit including an error amplifier, for comparison with a reference voltage and responsive correction, the improvement wherein said regulated power supply further includes: (A) first derivative feedback means adapted to feed back to said control circuit the first derivative of the output voltage in the multiple "b" in which: b=(L/R)+Cr; and (B) second derivative feedback means adapted to feed back to said control circuit the second derivative of the output voltage in the multiple "c" in which: c=LC(R+r)/R; (C) said error amplifier is characterized by: (1) a crossover frequency Ω 3 in radians per second; (2) an input impedance of value R 1 ohms; and (3) feedback loop comprising a feedback resistor of value R 2 ohms disposed in series with a first feedback capacitor of value C 1 farads, said feedback loop further comprising a second feedback capacitor of value C 2 farads, said second feedback capacitor being disposed in parallel with said feedback resistor; and wherein the value relationship among the components is given by: (D) Ω.sub.3 =(C.sub.2 R.sub.2 +C.sub.1 R.sub.2)/R.sub.1 C.sub.1 and (E) C.sub.2 R.sub.2 =rC.

Claim 9

The regulated power supply of claim 5 in which the relationship among the components is further defined by: R 1 C 1 >(C 1 +C 2 )R 2 .