A new gm-transimpedance instrumentation amplifier (GTIA) is introduced that enables precision signal acquisition with low-power operation. The GTIA architecture employs an input current-mode gm stage to achieve high-linearity and low-noise specs simultaneously. For biomedical applications, a bootstrapped AC coupling scheme is devised which maintains rail-to-rail electrode offset tolerance and gigaohms level input impedance. The amplifier gain is set by a single feedback resistor to over 80 dB with 2nd-order bandpass filter response. Also, an innovative feedforward biasing technique is proposed that yields robust operation along with adaption to different ranges of supply voltage. The circuit is implemented in 0.18 $\mathrm{\mu }$m CMOS process and consumes 40 and only 1.12 $\mathrm{\mu }$W of power at 1.2 and 0.8 V. Several simulations have been carried out to characterize the designed GTIA. Total input-referred noise equals 0.88 and 3.17 $\mathrm{\mu }$V_RMS within frequencies of 0.5–100 and 0.1–150 k Hz, respectively. Input offset voltage equals 2.6 $\mathrm{\mu }$V regulated via the DC servo loop (DSL) circuit which does not degrade the noise performance. CMRR of the designed GTIA is up to 105 dB without sensitivity to variation of the feedback resistor and the THD is less than 0.015% for a 2 mV_pp input signal.

推出了一种新型的gm跨阻仪表放大器（GTIA），它能够以低功耗操作实现精确的信号采集。GTIA架构采用输入电流模式gm级，以同时实现高线性度和低噪声规格。对于生物医学应用，设计了一种自举式AC耦合方案，该方案可保持轨到轨电极的偏移容差和千兆欧级输入阻抗。放大器的增益由单个反馈电阻器设置为超过80 dB，具有二阶带通滤波器响应。此外，提出了一种创新的前馈偏置技术，该技术可产生鲁棒的操作并适应不同的电源电压范围。该电路以0.18实现$\mathrm{\mu }$m CMOS工艺，仅消耗40和1.12 $\mathrm{\mu }$W在1.2和0.8 V时的功率。已进行了一些仿真来表征设计的GTIA。输入总噪声等于0.88和3.17$\mathrm{\mu }$V _RMS分别在0.5–100和0.1–150 k Hz的频率内。输入失调电压等于2.6$\mathrm{\mu }$通过直流伺服环路（DSL）电路调节的V，不会降低噪声性能。设计的GTIA的CMRR高达105 dB，对反馈电阻的变化不敏感，对于2 mV _pp输入信号，THD小于0.015％。