Technique for controlling the slope of a periodic waveform
First Claim
1. A circuit for forming a periodic waveform comprising:
- a. means for integrating a current for forming a voltage;
b. a transconductance amplifier for forming the current coupled to the means for integrating the current;
c. means for periodically alternating a direction of the current coupled to the transconductance amplifier;
d. means for controlling a level of the current coupled to the transconductance amplifier; and
e. means for sensing a level of the voltage wherein the means for controlling controls the level of the current according to the level of the voltage.
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Accused Products
Abstract
A circuit for forming a substantially periodic signal having a linear relationship between amplitude and time over a portion of its period, wherein a slope in the linear portion is controllable. A transconductance amplifier has a gain which is controllable depending upon a level of biasing current. A capacitor is coupled to an output of the transconductance amplifier wherein a voltage level on the capacitor defines the periodic waveform. Logic signals coupled to inputs to the transconductance amplifier control a direction of current flow from the transconductance amplifier to charge and discharge the capacitor. The biasing current is controllable to control a slope of the periodic waveform. In the preferred embodiment, the invention is used in conjunction with a circuit for forming pulses centered about positive zero crossings of a sinusoidal signal. The biasing current to the transconductance amplifier has two components. A first component of the biasing current is constantly supplied and a second component of the biasing current is selectively supplied. Therefore, the slope of the waveform may have one of two values depending upon whether or not the second component of the biasing current is selected to increase the biasing current of the transconductance amplifier.
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Citations
31 Claims
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1. A circuit for forming a periodic waveform comprising:
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a. means for integrating a current for forming a voltage; b. a transconductance amplifier for forming the current coupled to the means for integrating the current; c. means for periodically alternating a direction of the current coupled to the transconductance amplifier; d. means for controlling a level of the current coupled to the transconductance amplifier; and e. means for sensing a level of the voltage wherein the means for controlling controls the level of the current according to the level of the voltage.
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2. A circuit for forming a periodic waveform comprising:
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a. means for integrating a current for forming a voltage; b. a transconductance amplifier for forming the current coupled to the means for integrating the current; c. means for periodically alternating a direction of the current coupled to the transconductance amplifier; d. means for controlling a level of the current coupled to the transconductance amplifier; e. means for initializing the voltage. - View Dependent Claims (3)
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4. A circuit for forming a periodic waveform comprising:
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a. a charge storage device wherein a voltage level on the charge storage device forms the periodic waveform; b. a transconductance amplifier having a first pair of differential inputs, a first biasing input and a first output, wherein the first output is coupled to the charge storage device; c. a logic circuit for forming a logic signal coupled to a selected one of the first pair of differential inputs for controlling a direction of output current according to a level of the logic signal; and d. a biasing circuit coupled to the first biasing input for controlling a level of output current. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 22, 23)
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15. A method of forming a periodic waveform comprising the steps of:
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a. biasing a transconductance amplifier with a first biasing current; b. periodically charging and discharging a capacitor with the transconductance amplifier wherein a voltage level on the capacitor forms the periodic waveform and wherein the periodic waveform has a first positive slope and a first negative slope when the transconductance amplifier is biased with the first biasing current; and c. selectively biasing the transconductance amplifier with a second biasing current wherein the periodic waveform has a second positive slope and a second negative slope when the transconductance amplifier is biased with both the first biasing current and the second biasing current. - View Dependent Claims (16, 17, 18, 19, 24)
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20. A circuit for forming a periodic waveform comprising:
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a. means for integrating a current for forming a voltage; b. a transconductance amplifier for forming the current coupled to the means for integrating the current; c. means for periodically alternating a direction of the current coupled to the transconductance amplifier; d. means for controlling a level of the current coupled to the transconductance amplifier wherein the means for controlling a level of the current forms a biasing current having two levels wherein the biasing current is at a first level when the voltage on the means for integrating is below a predetermined level and the biasing current is at a second level when the voltage on the means for integrating is above the predetermined level and wherein the level of the current formed by the transconductance amplifier is responsive to the biasing current. - View Dependent Claims (21)
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25. A circuit for forming a periodic waveform comprising:
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a. means for integrating a current for forming a voltage; b. a transconductance amplifier for forming the current coupled to the means for integrating the current; c. a logic circuit for forming a logic signal coupled to the transconductance amplifier wherein a direction of the current is periodically alternated according to a level of the logic signal; and d. means for controlling a level of the current coupled to the transconductance amplifier. - View Dependent Claims (26, 27, 28, 29, 30, 31)
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Specification