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variable gain amplifier
Vertaling van "variable gain amplifier" in Chinees
可变增益放大器
measure an amplitude of an analog signal coupled to the variable gain amplifier,
测量与可变增益放大器耦合的模拟信号的振幅，
adjust a first gain of the variable gain amplifier according to a first gain function, and
根据第一增益函数调整可变增益放大器的第一增益，并且
The LTC6412 is a fully differential variable gain amplifier with linear-in-dB analog gain control.
LTC6412 是一款全差分可变增益放大器，采用对数线性模拟增益控制。
Figure 1c illustrates variable gain amplifier 106 according to an embodiment of the present invention. Variable gain amplifier 106 includes attenuator 126 followed by amplifier 128. In an embodiment, attenuator 126 may be implemented using a selectable capacitor array, a selectable resistor array, or other active or passive attenuator structures. In an embodiment, the selectable resistor array may be used to shift the corner frequency of an electrical high-pass transfer function in order to provide an adjustable attenuation, where the lower corner frequency is a function of the capacitance of the capacitive sensor and the input impedance of IC 100. Amplifier 128 converts single ended input signal 127 to differential output signal Vp and Vn. Attenuator 126 and amplifier 128 may be implemented using circuits described in co-pending applications 13/183,193 and 13/217,890, or using other amplifier structures known in the art. Alternatively, the gain of amplifier 128 may also be controlled by gain control signal GC1.
图1c图解了根据本发明一个实施例的可变增益放大器106。可变增益放大器106包括放大器128前面的衰减器126。在一个实施例中，可使用可选电容器阵列、可选电阻器阵列或其他有源或无源衰减器结构实施衰减器126。在一个实施例中，所述可选电阻器阵列可用于转换电高通转移函数的转角频率，以提供可调衰减，其中，较低转角频率为电容传感器的电容和IC 100的输入阻抗的函数。放大器128将单端输入信号127转换为差分输出信号Vp和Vn。可使用共同待决申请13/183，193和13/217，890所述的电路，或使用本领域中已知的其他放大器结构实施衰减器126和放大器128。可替代地，放大器128的增益还可由增益控制信号GC1控制。
Figure 1b illustrates an embodiment implementation of signal detection and level adaptation block 112. Peak detector 122 detects peak signals at the output of variable gain amplifier 106 and controller 124 controls the gain of variable gain amplifier 106 via gain control signal GC1 and the gain of digital gain block 110 via gain control signal GC2 according to the output of peak detector 122. Gain control signal GC1 may be implemented using a digital word, a pulse modulated signal, or an analog signal such as a current or a voltage. Gain control signal GC2 is implemented, for example, as a digital word or a pulse modulated digital signal.
图1b图解了信号检测和电平自适应块112的示例实施方式。峰值检测器122检测可变增益放大器106的输出端的峰值信号，控制器124根据峰值检测器122的输出通过增益控制信号GC1控制可变增益放大器106的增益，并通过增益控制信号GC2控制数字增益模块110的增益。可使用数字字、脉冲调制信号或模拟信号（例如，电流或电压）实施增益控制信号GC1。增益控制信号GC2实施为（例如）数字字或脉冲调制数字信号。
In some embodiments, the system also includes the capacitive signal source, which may be a MEMS microphone, or other type of microphone. In some embodiments, the system also includes a digital noise shaper coupled to an output of the digital gain block. The digital noise shaper may include a one-bit bitstream output. In some embodiments the digital gain block includes a digital filter, and the gain control circuit is configured to adjust the second gain by adjusting filter coefficients of the digital filter. In an embodiment, the variable gain amplifier, the analog-to-digital converter, and the gain control circuit is disposed on an integrated circuit.
在某些实施例中，所述系统还包括电容信号源，其可为MEMS麦克风或其他类型的麦克风。在某些实施例中，所述系统还包括与数字增益块的输出耦合的数字噪音整形器。所述数字噪音整形器可包括单位位流输出。在某些实施例中，所述数字增益块包括数字滤波器，所述增益控制电路用于通过调整数字滤波器的滤波系数而调整第二增益。在一个实施例中，所述可变增益放大器、模数转换器和增益控制电路布置在集成电路上。
In an embodiment, signal detection and level adaptation block 112 measures an amplitude at the output of variable gain amplifier 106, and calculates gain control signals GC1 and GC2 as a function of the measured amplitude. Alternatively, signal detection and level adaptation block 112 may measure the amplitude of the signal input to amplifier 106. Signal detection and level adaptation block 112, in some embodiments, decreases the gain of variable gain amplifier 106 in response to increasing amplitudes output from capacitive signal source or microphone 102. As signal detection and level adaptation block 112 decreases the gain of variable gain amplifier 106 via GC1, a corresponding increase is made to the gain of variable gain digital block 110. By applying a corresponding increase to digital gain block 110 in response to a decrease in the gain of variable gain amplifier 106, the sensitivity of the microphone system is linear over a very wide dynamic range.
在一个实施例中，信号检测和电平自适应块112测量可变增益放大器106的输出端的振幅，并将增益控制信号GC1和GC2作为测量振幅的函数而对其进行计算。可替代地，信号检测和电平自适应块112可测量放大器106的信号输入的振幅。在某些实施例中，电容信号源或麦克风102输出的振幅增加时，信号检测和电平自适应块112减少可变增益放大器106的增益。信号检测和电平自适应块112通过GC1减少可变增益放大器106的增益时，可变数字增益模块110的增益相应增加。通过在可变增益放大器106的增益减少时相应增加数字增益模块110的增益，麦克风系统的敏感度在非常大的动态范围内都为线性。
Figures 4a-d illustrate an embodiment gain profiles that may be implemented using embodiment systems, for example 100 illustrated in Figure 1a and in system 200 illustrated in Figure 2a. Figure 4a illustrates an embodiment gain level versus sound level input diagram. Curve 402 represents the gain of an input variable gain amplifier, and curve 404 represents the gain of the digital gain block. Dotted line 406 represents a threshold level above which compression is applied to the input variable gain amplifier and decompression is applied to the digital gain block. According to Figure 4a, the input variable gain amplifier is set to have a gain of about 10 dB, and the digital gain block is set to have a gain of about -20 dB for input sound pressure levels up to about 115 dB SPL. Above this level, the gain of the input variable gain amplifier is reduced one dB for every one dB increase in input sound pressure level. Accordingly, the gain of the digital decompression block is increased one dB for every one dB increase in input sound pressure level above threshold 406. It should be appreciated that the decompression profile of Figure 4a is just one example of many possible gain profiles. In alternative embodiments of the present invention, initial gains and thresholds may differ according to the particular microphone or capacitive sensor used.
图4a-d图解了可使用示例系统，例如，图1a所示的100和图2a所示的系统200实施的示例增益曲线。图4a图解了示例增益电平与声级输入图。曲线402代表输入可变增益放大器的增益，曲线404代表数字增益块的增益。虚线406代表阈值电平，若超过阈值电平，对输入可变增益放大器进行压缩，对数字增益块进行解压。根据图4a，对于达到约115 dB SPL的声压级，输入可变增益放大器的增益设为约10 dB，数字增益块的增益设为约-20 dB。超过该声压级时，输入声压级每增加一dB，将输入可变增益放大器的增益减少一dB。由此，超过阈值406时，输入声压级每增加一dB，将数字解压块的增益增加一dB。应理解的是，图4a的解压曲线仅为多种可能增益曲线的一个示例。在本发明的替代实施例中，根据使用的特定麦克风或电容传感器，初始增益和阈值可有所不同。
In accordance with a further embodiment, the system for amplifying a signal provided by a capacitive signal source includes a variable gain amplifier, an analog to digital converter, a digital gain block, and a gain control circuit. The variable gain amplifier includes an input node that is configured to be coupled to the capacitive signal source. The analog to digital converter is coupled to an output of the variable gain amplifier, and the digital gain block is coupled to an output of the analog to digital converter. The gain control block is configured to measure an amplitude of an analog signal coupled to the variable gain amplifier, and adjust the first gain of the variable gain amplifier according to a first gain function, and adjust the second gain of the digital gain block according to a second gain function. In some embodiments, the variable gain amplifier comprises a gain setting in which the gain of the variable gain amplifier is less than one.
根据一个进一步实施例，用于放大电容信号源提供的信号的系统包括可变增益放大器、模数转换器、数字增益块和增益控制电路。所述可变增益放大器包括用于与电容信号源耦合的输入节点。所述模数转换器与可变增益放大器的输出耦合，所述数字增益块与模数转换器的输出耦合。所述增益控制块用于测量与可变增益放大器耦合的模拟信号的振幅，根据第一增益函数调整可变增益放大器的第一增益，并根据第二增益函数调整数字增益块的第二增益。在某些实施例中，所述可变增益放大器包括可变增益放大器的增益小于一的增益设置。
In some embodiments, the gain of variable gain amplifier 106 and the gain of digital gain block 110 is fixed for input levels up to a predetermined threshold. Above this threshold, compression is applied to variable gain amplifier 106 and expansion is applied to digital gain block 110. In one embodiment, this threshold is set to be at about 115 dB SPL. Alternatively, other thresholds may be used. In some embodiments, this threshold is set in order to use as much of the input dynamic range of A/D converter 108 as possible without clipping the input of A/D converter 108 at high signal levels, and/or without causing excessive audio distortion at high input levels. In alternative embodiments, or in alternative modes, signal detection and level adaptation block 112 may be configured to provide signal amplification at variable gain amplifier 106 and compression at digital gain block 110 at lower input levels in order to further reduce the noise contribution of the ADC, and in order to relax the system's design requirements regarding area and current consumption. For example, using a higher gain at lower input levels deemphasizes the noise contribution of A/D converter 108 by allowing the noise contribution of capacitive input source 102 and the input stage of variable gain amplifier 106 to become more dominant, thereby resulting in a lower input referred noise level at lower input levels.
在某些实施例中，对于达到预定阈值的输入电平，可变增益放大器106的增益和数字增益模块110的增益固定。超过该阈值时，对可变增益放大器106进行压缩，对数字增益模块110进行扩展。在一个实施例中，该阈值设为约115 dB SPL。可替代地，可采用其他阈值。在某些实施例中，按顺序设置该阈值，以使用尽可能多的模数转换器108的输入动态范围，但不会对高信号电平下的模数转换器108的输入进行限幅，和/或在高输入电平下造成过大音频失真。在替代实施例中，或在替代模式下，信号检测和电平自适应块112可用于在可变增益放大器106上提供信号放大，并在低输入电平下的数字增益模块110上进行压缩，以进一步减少ADC的噪声成分，并降低面积和电流消耗方面的系统设计要求。例如，通过增加电容输入源102的噪声成分和可变增益放大器106的输入级的重要性，在较低输入电平下使用较高增益会降低模数转换器108的噪声成分，从而降低较低输入电平下的输入相关噪声电平。
Figure 4c illustrates a gain level versus sound level input diagram according to an alternative embodiment. Curve 414 represents the gain of an input variable gain amplifier, and curve 412 represents the gain of the digital gain block. According to Figure 4c, the input variable gain amplifier provides an increasing gain with decreasing input sound pressure level that extends down to lower input levels, while the digital gain block provides a corresponding decreasing gain with decreasing input sound pressure levels. Curve 416 in Figure 4d represents the system gain response that corresponds to the gain curves of Figure 4c. In an embodiment, providing an increased gain at lower input levels may reduce noise of the A/D, as referred to the input of the variable gain amplifier, or if the same noise level should be reached, a higher noise contribution of the ADC is possible resulting in smaller area and less current consumption for the ADC.
图4c图解了根据一个替代实施例的增益电平和声级输入图。曲线414代表输入可变增益放大器的增益，曲线412代表数字增益块的增益。根据图4c，随着输入声压级降低到低输入电平，所述输入可变增益放大器提供增加增益，而数字增益块随着输入声压级的降低提供对应减少增益。图4d中的曲线416代表与图4c中的增益曲线对应的系统增益响应。在一个实施例中，如果低输入电平下的增加增益（称为可变增益放大器的输入）可降低模数转换器的噪声，或者，如果达到相同噪声电平，ADC的噪声成分可能较高，使ADC的面积较小，电流消耗较少。
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Synoniemen voor variable gain amplifier in het Engels
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