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2. 发明申请

WO2017112819A1 LOOP FILTER WITH ACTIVE DISCRETE-LEVEL LOOP FILTER CAPACITOR IN VCO 审中-公开
标题翻译：环路滤波器，带有VCO中的主动离散环路滤波电容
公开(公告)号：WO2017112819A1
公开(公告)日：2017-06-29
申请号：PCT/US2016/068132
申请日：2016-12-21
申请人： TEXAS INSTRUMENTS INCORPORATED , TEXAS INSTRUMENTS JAPAN LIMITED
发明人： FINN, Steven, Ernest
IPC分类号： H03B29/00 , H03L7/085
CPC分类号： H03L7/0891 , H03L7/0807 , H03L7/093 , H03L7/099
摘要： In described examples, a loop filter with an active discrete-level loop filter capacitor (300) can be used in a VCO (such as for CDR). In described examples, a loop filter capacitor function is simulated by sensing input loop filter current (such as with a current mirror (312) and source follower (Ml) in an input leg), and forcing back a loop filter (VCO) control voltage (VI at Nl). Loop filter voltage control is provided using a VDAC (311) with a discrete-level VDAC feedback voltage (VDAC), incremented/decremented (314, 316, 322) based on the sensed loop filter current (12). In one embodiment, the VDAC voltage (311) is provided as the non-inverting input to an amplifier (326), with the inverting input providing the control voltage (VI at Nl), forced to the VDAC feedback voltage. The VDAC feedback voltage can be provided by increment/decrement comparators (314, 316) based on a voltage deviation on a C2 capacitor (from a reference voltage) that receives the sensed loop filter current (effectively multiplying the C2 capacitance to provide a simulated loop filter capacitance).
摘要翻译：在所描述的示例中，具有有源离散电平环路滤波电容器（300）的环路滤波器可以用于VCO（例如用于CDR）中。在所描述的示例中，通过感测输入环路滤波器电流（例如利用输入支路中的电流镜像电路（312）和源极跟随器（M1））来模拟环路滤波器电容器功能，并且强制回送环路滤波器（VCO）控制电压（在N1的VI）。基于感测到的环路滤波器电流（12），使用具有离散电平VDAC反馈电压（VDAC）的VDAC（311）提供环路滤波器电压控制，递增/递减（314,316,322）。在一个实施例中，将VDAC电压（311）作为非反相输入提供给放大器（326），反相输入提供控制电压（VI处于N1），强制为VDAC反馈电压。 VDAC反馈电压可以通过增量/减量比较器（314,316）基于C2电容器上的电压偏差（来自参考电压）来提供，所述C2电容器接收感测的环路滤波器电流（有效地乘以C2电容以提供模拟环路滤波电容）。

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