Digital to analog signal converter
First Claim
1. A D to A converter stage comprising:
- a current mirror including an input transistor and an output transistor connected to a supply voltage, the input transistor also being connected to a reference current source and the output transistor being connected to an output for the current mirror;
a current adjusting transistor in parallel with each of the input and output transistors for adjusting the output current of the current mirror as a function of the operating states of the current adjusting transistors;
digital signal activated switch means for selectively controlling operation of each current adjusting transistor; and
circuit means for regulating drain voltages on the input and output transistors whereby the values of currents flowing in the input and output transistors and hence the value of the output current is a direct function of the relative geometric sizes of the input, output and current adjusting transistors.
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Accused Products
Abstract
A D to A converter comprising a series of stages each including a current mirror having an input and an output transistor (Q1 and Q3) and a current adjusting transistor (Q2, Q4) connected in parallel with each input and output transistor for adjusting the output current from the current mirror as a function of the operating states of the current adjusting transistors. The operating state of each current adjusting transistor is controlled by a digital signal applied to a switch (Q2S, Q2S'"'"') connected to the gate of each current adjusting transistor. Each stage also includes a control circuit (Q1C, Q3C) for maintaining equal the drain voltages of its input and output transistors whereby the current changes introduced in the output current of the converter stage are functions of the relative geometric sizes of the input, output and current adjusting transistors comprising the converter stage.
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Citations
11 Claims
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1. A D to A converter stage comprising:
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a current mirror including an input transistor and an output transistor connected to a supply voltage, the input transistor also being connected to a reference current source and the output transistor being connected to an output for the current mirror; a current adjusting transistor in parallel with each of the input and output transistors for adjusting the output current of the current mirror as a function of the operating states of the current adjusting transistors; digital signal activated switch means for selectively controlling operation of each current adjusting transistor; and circuit means for regulating drain voltages on the input and output transistors whereby the values of currents flowing in the input and output transistors and hence the value of the output current is a direct function of the relative geometric sizes of the input, output and current adjusting transistors. - View Dependent Claims (2, 3, 4, 5)
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6. A D to A converter comprising:
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a series of current mirrors each including an input and an output transistor connected to a supply voltage, a first one of the input transistors being connected to a reference current source, each output transistor being connected to a output for the current mirror in which it is included; a current adjusting transistor in parallel with each input and output transistor for adjusting the output current of the current mirror in which it is included as a function of its operating state; digital signal activated switch means for selectively controlling operation of each current adjusting transistor; and circuit means for regulating drain voltages on each input and output transistor whereby the values of currents flowing in the input and output transistors and hence the value of each current mirror output current is a direct function of the relative sizes of the input, output and current adjusting transistors comprising the current mirror. - View Dependent Claims (7, 8, 9)
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10. A D to A converter stage comprising:
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a current mirror including an input transistor and an output transistor connected to a supply voltage, the input transistor also being connected to a reference current source and the output transistor being connected to an output for the current mirror; a current adjusting transistor in parallel with each of the input and output transistors for adjusting the output current of the current mirror as a function of the operating states of the current adjusting transistors; and digital signal activated switch means connected to a gate of each current adjusting transistor for selectively controlling operation of each current adjusting transistor. - View Dependent Claims (11)
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Specification