BROADBAND DRIVER WITH EXTENDED LINEAR OUTPUT VOLTAGE
First Claim
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1. A transmitter driver for preparing input electrical signals for output to a modulator comprising:
- first and second inputs for inputting first and second input electrical signals;
a buffer stage for shifting a reference of the first and second input electrical signals;
an amplifier stage receiving the first and second input electrical signals, including;
first and second differential pair transistors forming a differential pair connected to the buffer stage;
first and second outputs connected to second terminals of the first and second differential pair transistors, respectively, for outputting first and second output electrical signals;
first and second auxiliary transistors connected to the second terminals of the first and second differential pair transistors, wherein the first and second auxiliary transistors are capable of turning on when the first and second input electrical signals exceed a maximum input voltage of a linear region of a transfer function of the first and second differential transistors for increasing the first and second output electrical signals, thereby increasing a linear region of a transfer function of the amplifier stage.
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Abstract
Modern modulator drivers must be capable of delivering a large output voltage into a tens of ohms modulator, while minimizing the amount of distortion added by the driver. The driver should deliver the output voltage without exceeding a maximum distortion while minimizing the DC power consumption. Accordingly, a modulator driver includes a final stage amplifier with auxiliary transistors that turn on when the conventional differential pair of transistors approaches their maximum voltage of the linear region of their transfer function, thereby providing a more linear transfer function, in particular at large input voltages.
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Citations
18 Claims
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1. A transmitter driver for preparing input electrical signals for output to a modulator comprising:
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first and second inputs for inputting first and second input electrical signals; a buffer stage for shifting a reference of the first and second input electrical signals; an amplifier stage receiving the first and second input electrical signals, including; first and second differential pair transistors forming a differential pair connected to the buffer stage; first and second outputs connected to second terminals of the first and second differential pair transistors, respectively, for outputting first and second output electrical signals; first and second auxiliary transistors connected to the second terminals of the first and second differential pair transistors, wherein the first and second auxiliary transistors are capable of turning on when the first and second input electrical signals exceed a maximum input voltage of a linear region of a transfer function of the first and second differential transistors for increasing the first and second output electrical signals, thereby increasing a linear region of a transfer function of the amplifier stage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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Specification