1. An audio amplifier comprising:
an output stage for generating an output stage voltage in response to an input signal and an output stage quiescent current;
a controlled current source, operatively coupled to the output stage, for controlling the output stage quiescent current in response to a quiescent current signal during a start-up cycle;
a ramp generator, operatively coupled to the output stage, for generating a ramp signal during the start-up cycle;
wherein the output stage, based on the ramp signal, ramps the output stage voltage from a supply voltage to a quiescent voltage; and
a signal operatively coupled to the ramp generator, for generating the quiescent current signal as a function of the ramp signal.
2. The audio amplifier of claim 1 wherein the quiescent current signal is a nonlinear function of the ramp signal.
3. An audio amplifier comprising:
an output stage for generating an output stage voltage in response to an input signal and an output stage quiescent current;
a controlled current source, operatively coupled to the output stage, for controlling the output stage quiescent current in response to a quiescent current signal during a start-up cycle; and
wherein the output stage quiescent current has a magnitude and the output stage voltage ramps during the start-up cycle and wherein the controlled current source controls the magnitude of the output stage quiescent current to increase monotonically with the ramping of the output stage voltage during the start-up cycle.
4. The audio amplifier of claim 1 wherein the controlled current source produces an offset current during the start-up cycle when the output stage voltage is ground.
5. The audio amplifier of claim 1 wherein the controlled current source includes a current mirror circuit.
6. The audio amplifier of claim 1 wherein the output stage and the controlled current source are implemented on an integrated circuit.
7. An method comprising:
controlling an output stage quiescent current of an audio amplifier during a start-up cycle and in response to a quiescent current signal;
ramping an output stage voltage of the audio amplifier from a supply voltage to a quiescent voltage during the start-up cycle; and
wherein the quiescent current signal is a function of the output stage voltage during the start-up cycle.
8. The method of claim 7 wherein the step of controlling the output stage quiescent current includes controlling the output stage quiescent current to an offset current during the start-up cycle when the output stage voltage is the supply voltage.
9. The method of claim 7 wherein the quiescent current signal is a nonlinear function of the output stage voltage during the start-up cycle.
10. The method of claim 7 wherein the output stage quiescent current signal has a magnitude that increases monotonically with ramping output stage voltage during the start-up cycle.
11. An method for starting an audio amplifier comprising:
applying an output stage quiescent current to an output stage of the audio amplifier;
ramping an output voltage of the output stage from a supply voltage to a quiescent voltage;
increasing a magnitude of the output stage quiescent current to an operating current level;
applying an input voltage to the audio amplifier after the output voltage has reached the quiescent voltage and the magnitude of the output stage quiescent current has reached the operating current level; and
wherein the step of increasing the magnitude of the output stage quiescent current includes controlling the magnitude of the output stage quiescent current as a function of the output stage voltage.
12. The method of claim 11 wherein the step of increasing the magnitude of the output stage quiescent current includes controlling the magnitude of the output stage quiescent current as a non-linear function of the output stage voltage.
13. The method of claim 11 wherein the step of increasing the magnitude of the output stage quiescent current includes increasing the magnitude of the output stage quiescent current monotonically with ramping output stage voltage.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method for producing an aqueous solution of a quaternary ammonium hydroxide which comprises the steps of:
synthesizing a quaternary ammonium inorganic acid salt by the reaction of a trialkylamine with a dialkyl carbonate; and
electrolyzing the inorganic acid salt in an electrolytic cell partitioned by a cation exchange membrane with the use of an electrode for electrolysis, wherein
the electrode comprises:
an electrode base material of an electrically conductive metal of a metal selected from the group consisting of Ti, Ta, Nb and Zr or an alloy of at least one metal selected from the group consisting of Ti, Ta, Nb and Zr;
an electrode active layer of a mixed oxide of an oxide of Sn and an oxide of at least one metal selected from the group consisting of In and Ir covering the electrode base material; and
an intermediate layer of a mixed oxide of an oxide of Sn and an oxide of at least one metal selected from the group consisting of In and Ir disposed between the electrode base material and the electrode active layer,
wherein a content of Sn in the mixed oxide forming the electrode active layer is 50-80% by weight,
a content of Sn in the mixed oxide forming the intermediate layer is 50-80% by weight, and
the mixed oxide of the intermediate layer further contains an oxide of at least one metal selected from the group consisting of Ti, Ta and Nb, and the mixed oxide of the electrode active layer does not contain essentially an oxide of an oxide of the electrically conductive metal.
2. The method as described in claim 1, wherein the quaternary ammonium inorganic acid salt is a compound represented by the following general formula (1)
wherein R1, R2, R3, and R4 are methyl or ethyl and they may be identical with or different from one another.
3. The method as described in claim 1, wherein the quaternary ammonium hydroxide is tetramethylammonium hydroxide.
4. The method as described in any one of claims 1, 2, and 3, wherein the electrode base material is either the electrically conductive metal of Ti or the electrically conductive metal of alloy of Ti.
5. The method as described in claim 4, wherein the mixed oxide of the electrode active layer is the oxide of Sn and the oxide of Ir.
6. The method as described in claim 4, wherein the mixed oxide of the intermediate layer is the oxide of Sn, the oxide of In and the oxide of Ti.
7. A method for producing an aqueous solution of a quaternary ammonium hydroxide which comprises the steps of:
synthesizing a quaternary ammonium inorganic acid salt by the reaction of a trialkylamine with a dialkyl carbonate; and
electrolyzing the inorganic acid salt in an electrolytic cell partitioned by a cation exchange membrane with the use of an electrode for electrolysis, wherein
the electrode comprises:
an electrode base material of an electrically conductive metal of a metal selected from the group consisting of Ti, Ta, Nb and Zr or an alloy of at least one metal selected from the group consisting of Ti, Ta, Nb and Zr;
an electrode active layer of a mixed oxide of an oxide of Sn and an oxide of at least one metal selected from the group consisting of In and Ir covering the electrode base material; and
an intermediate layer of a mixed oxide of an oxide of Sn and an oxide of at least one metal selected from the group consisting of In and Ir disposed between the electrode base material and the electrode active layer,
wherein a content of Sn in the mixed oxide forming the electrode active layer is 50-80% by weight,
a content of Sn in the mixed oxide forming the intermediate layer is 50-80% by weight,
the mixed oxide of the intermediate layer further contains an oxide of at least one metal selected from the group consisting of Ti, Ta and Nb, and
the mixed oxide of the electrode active layer consists essentially of the oxide of Sn and the oxide of at least one metal selected from the group consisting of In and Ir.