This article presents a discrete-time parametric amplifier (DTPA) as the signal demodulator for chopper amplifier. Unlike the conventional chopper, the DTPA demodulator features noise-efficient gain augmentation while demodulating the chopped signal. The demodulator also enables low-frequency noise cancellation during the inherent track-and-hold (T/H) process of the charge parametrization. The positive feedback loop and the dc servo loop are implemented for applications requiring larger input impedance and dc input offset cancellation using a bandpass transfer function. Design considerations for the DTPA-based demodulator circuit and the merits and demerits of the chopper–DTPA amplifier are discussed as well. The proposed design has been fabricated in a standard 180-nm CMOS technology node. The complete design occupies 0.127 mm² of the die area and consumes 2.4- $\mu \text{W}$ power from a 1.5 V of $\text{V}_{\text {DD}}$ . The measurement results show that the DTPA demodulator provides 8-dB gain enhancement while improving on the prior art of T/H-based demodulator and the amplifier achieves input referred noise voltage of $2~ \mu \text {V}_{\text {rms}}$ in 143-Hz bandwidth.

中文翻译：

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基于离散时间 MOS 参数放大器的斩波信号解调器

本文介绍了一种离散时间参数放大器 (DTPA) 作为斩波放大器的信号解调器。与传统斩波器不同，DTPA 解调器在解调斩波信号时具有噪声高效增益增强功能。解调器还可以在电荷参数化的固有采样保持 (T/H) 过程中消除低频噪声。正反馈回路和直流伺服回路适用于需要更大输入阻抗和使用带通传递函数消除直流输入偏移的应用。还讨论了基于 DTPA 的解调器电路的设计注意事项以及斩波器-DTPA 放大器的优缺点。所提议的设计是在标准的 180 纳米 CMOS 技术节点中制造的。完整的设计占地 0.127 毫米²的芯片面积并消耗 2.4- $\mu \text{W}$ 来自 1.5 V 的电源 $\text{V}_{\text {DD}}$ . 测量结果表明，DTPA解调器在改进基于T/H的解调器的现有技术的同时提供了8dB的增益增强，放大器实现了输入参考噪声电压为 $2~ \mu \text {V}_{\text {rms}}$ 在 143Hz 带宽中。