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Switching circuit, and a modulator, demodulator or mixer including such a circuit

A technology for switching circuits and modulators, which is applied in the direction of demodulation, modulation transfer, modulation conversion balance device, etc., and can solve problems such as output noise and serious output noise

Active Publication Date: 2008-12-24
MEDIATEK INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although this modulator works well, it exhibits significant output noise which, when attempting to operate at increased output power, will increase the current required to drive the gate of the switching transistor (switching transistor). become serious

Method used

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  • Switching circuit, and a modulator, demodulator or mixer including such a circuit
  • Switching circuit, and a modulator, demodulator or mixer including such a circuit
  • Switching circuit, and a modulator, demodulator or mixer including such a circuit

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Embodiment Construction

[0054] It is worth considering how prior art modulators operate to understand their limitations. The prior art modulator of FIG. 2 includes the same four independent modulator switching circuits 10 , 12 , 14 and 16 . Therefore, only the first switching circuit 10 needs to be described in detail. The first switching circuit 10 comprises a first switching transistor 20 and a second switching transistor 22 connected in a "differential" configuration. Therefore, the source of the first transistor 20 and the source of the second transistor 22 are connected to the common node 24 . The drain of the first transistor 20 is connected to a first terminal of the center tapped coil 26 and the drain of the transistor 22 is connected to a second terminal of the second tapped coil 26 . The center tap of the coil 26 is connected to a supply rail 28 . The current received by common node 24 represents the baseband signal to be modulated. This current may be generated by a voltage-to-current ...

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PUM

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Abstract

A switching circuit comprising: first and second steering switches operable to make or break a path between first and second terminals thereof, and each steering switch further having a control terminal for controlling the switch, the first and second steering switches having their control terminals driven by first and second switching signals, the first and second switching signals having a first frequency and the second switching signal being in anti-phase with the first switching signal and a first chopping switch operable to make or break a path between first and second terminals thereof and being connected in series with at least one of the first and second steering switches and receiving at its first terminal an input to be modulated, wherein the control terminal of the chopping switch is driven by a first switching control signal such that the chopping switch is non-conducting while the first and second steering switches are changing between being conducting and being non-conducting.

Description

technical field [0001] The invention relates to a switching circuit for use inside a modulator or demodulator or mixer, and a modulator or demodulator or mixer comprising such a circuit. Background technique [0002] Many transmission schemes encode data by modulating the amplitude and phase of a carrier to represent figure 1 Symbols within a constellation diagram of the type shown. The constellation diagram has axes extending in real and imaginary directions. The real and imaginary directions are orthogonal. In the actual expression, if the real direction is represented by a sinusoidal curve sin(ωt), the imaginary direction is represented by sin ( ωt + π 2 ) = cos ( ωt ) express. Thus, an arbitrary symbol such as that designated by reference 2 can be represented by a suitable combin...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03D7/14H04L27/36
CPCH03D7/1441H04L27/36H03D7/1458H03D7/165H03D2200/0084H03D2200/009
Inventor 克里斯多佛·杰兰特·琼斯
Owner MEDIATEK INC
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