为提高运算放大器的带内增益和带宽，提出了一款应用于长期演进( LTE) 接收 机中宽带Δ-Σ模数转换器( ADC) 的四级运算放大器．该运算放大器采用前馈Gm-C 和密 勒补偿相结合的混合型频率补偿方法，以保证运算放大器的稳定性． 文中采用0. 13 μm 1P6M CMOS 工艺设计了一款高性能的四级运算放大器，并将该运算放大器应用于宽带 Δ-ΣADC 中．测试结果显示: 该运算放大器在1. 5 V 供电电压下可获得72. 8 dB 的直流增 益、442MHz 的增益带宽积和101V/μs 的转换率; 在相同的功耗和带宽下，该放大器的带 内( 0～10MHz) 增益比传统的两级放大器提高了6 dB 以上; 采用该运算放大器的宽带 Δ-ΣADC在10MHz 的信号带宽下具有68 dB 的信噪比和78 dB 的无杂散动态范围．

In order to improve the in-band gain and bandwidth of operational amplifiers,a four-stage operational amplifier of the broadband Δ-Σ ADC used in long-term evolution receivers is proposed.In the operational amplifier,a hybrid frequency compensation scheme combining feedforward Gm-C and Miller technique is adopted to ensure the stability.Then,a high-performance four-stage operational amplifier is designed in 0.13 μm 1P6M CMOS technology,and it is applied to the broadband Δ-Σ ADC.Test results show that ( 1) with a power supply of 1.5V,the operational amplifier achieves a unity gain bandwidth of 442MHz,a DC gain of 72.8dB and a slew rate of 101V/μs; ( 2) with the same bandwidth and power dissipation,the in-band ( 0 ～ 10MHz) gain of the proposed amplifier is 6 dB more than that of the traditional two-stage operational amplifier; and ( 3) in a signal bandwidth of 10MHz,the broadband Δ-Σ ADC adopting the proposed amplifier achieves a SNR of 68 dB and a SFDR of 78 dB.