Switched capacitor circuit capable of eliminating clock feedthrough for vco

A technique of capacitive circuit and punch-through effect, which is applied in power oscillators, electrical components, automatic power control, etc., can solve problems such as voltage-controlled oscillator 10 offset and drift, and achieve the effect of preventing instantaneous frequency offset and drift

Inactive Publication Date: 2005-02-02
MEDIATEK INC +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The above-mentioned step voltage changes and recovery generated at nodes A and B will change the capacitance value of the resonant cavity of the voltage-controlled oscillator 10, resulting in an instantaneous shift and drift of the frequency of the voltage-controlled oscillator 10

Method used

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  • Switched capacitor circuit capable of eliminating clock feedthrough for vco
  • Switched capacitor circuit capable of eliminating clock feedthrough for vco
  • Switched capacitor circuit capable of eliminating clock feedthrough for vco

Examples

Experimental program
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Embodiment Construction

[0067] see Figure 6 , Figure 6 It is a schematic diagram of the first embodiment of the single-ended switched capacitor circuit of the present invention. In this embodiment, the single-ended switched capacitor circuit 130 includes: a capacitor 132, a main switch element 134 (including an NMOS transistor), a dummy switch element (dummy switch element) 136 (including an NMOS transistor), and A control signal generator 138 . The control signal generator 138 can provide a first control signal SW1 and a second control signal SW2 , wherein the second control signal SW2 is inverse to the first control signal SW1 .

[0068] Figure 7It is a change graph of the first control signal SW1 and the second control signal SW2 generated by the control signal generator 138 with respect to time. Such as Figure 7 As shown, the switched capacitor circuit 130 is opened at time point t.

[0069] exist Figure 6 Among them, the capacitor 132 is connected between the first oscillation node O...

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Abstract

A differential switched capacitor circuit for use in a voltage controlled oscillator (VCO) capable of eliminating clock feedthrough and preventing an unwanted momentary frequency shift and drift in the VCO output frequency when the switched capacitor circuit is shut off. A center switch element connects a positive side capacitance node with a negative side capacitance node depending on a first control signal. A positive side primary switch element and a negative side primary switch element connect the positive and negative side capacitance nodes depending on the first control signal. A positive side additional switch element and negative side additional switch element with control signals complementary to the first control signal cancel the clock feedthrough of the center switch and the positive and negative side primary switch elements at the positive and negative side capacitance nodes respectively.

Description

technical field [0001] The present invention provides a switched capacitor circuit, especially a switched capacitor circuit used in a voltage-controlled oscillator, which can be used to eliminate the clock feedthrough effect, and thus prevent the switched capacitor circuit from When turned off or on, the voltage controlled oscillator exhibits instantaneous frequency shifts and drifts. Background technique [0002] A voltage controlled oscillator (VCO) is a component commonly used in wireless communication systems to perform frequency synthesis operations. For example, as described by Welland et al. in US Pat. Nos. 6,226,506 and 6,147,567, wireless communication systems generally require frequency synthesis operations to be performed on receive path circuitry and transmit path circuitry. [0003] figure 1 It is a schematic diagram of a digital tuning VCO 10 in a conventional technique. figure 1 The VCO 10 used in a frequency synthesizer is based on a typical resonant struc...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06G7/18H03B1/00H03B5/04H03L7/00H03L7/099
CPCH03B5/04
Inventor 柯凌维
Owner MEDIATEK INC
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