在无线接收机中,天线接收的信号强度往往变化很大,自动增益控制环路(automatic gain control,AGC)根据这个信号强度来动态调节控制放大器的增益,向后级基带电路(如ADC)提供幅度恒定的信号,使得接受到的不同强度信号均能被正确接收和解调...在无线接收机中,天线接收的信号强度往往变化很大,自动增益控制环路(automatic gain control,AGC)根据这个信号强度来动态调节控制放大器的增益,向后级基带电路(如ADC)提供幅度恒定的信号,使得接受到的不同强度信号均能被正确接收和解调;为了达到通过识别接收机接收信号的强度动态调节放大器的增益,以实现输出信号幅度恒定的目的,文章基于TSMC90nm CMOS工艺着重论述了针对70 MHz中频信号的AGC电路设计过程,详细设计了AGC各模块电路,并从提高线性度、降低直流失调和提高稳定性等方面对电路进行了优化,主要介绍AGC芯片的版图设计并进行了后仿,给出了整个AGC系统的工作特性和各项指标;在电路设计过程中,针对线性度、输出信号幅度、增益控制范围等进行改进与优化,得到符合设计指标的电路结构;最后对AGC环路的性能进行仿真验证,得到该AGC在满足输出信号幅度和线性度的基础上达到了30dB的动态范围,满足了接收机系统的要求。展开更多
A CMOS variable gain amplifier（VGA） that adopts a novel exponential gain approximation is presented.No additional exponential gain control circuit is required in the proposed VGA used in a direct conversion receiver...A CMOS variable gain amplifier（VGA） that adopts a novel exponential gain approximation is presented.No additional exponential gain control circuit is required in the proposed VGA used in a direct conversion receiver.A wide gain control voltage from 0.4 to 1.8 V and a high linearity performance are achieved.The three-stage VGA with automatic gain control（AGC） and DC offset cancellation（DCOC） is fabricated in a 0.18-μm CMOS technology and shows a linear gain range of more than 58-dB with a linearity error less than ±1 dB.The 3-dB bandwidth is over 8 MHz at all gain settings.The measured input-referred third intercept point（IIP3） of the proposed VGA varies from-18.1 to 13.5 dBm,and the measured noise figure varies from 27 to 65 dB at a frequency of 1 MHz.The dynamic range of the closed-loop AGC exceeds 56 dB,where the output signal-to-noise-and-distortion ratio（SNDR） reaches 20 dB.The whole circuit,occupying 0.3 mm^2 of chip area,dissipates less than 3.7 mA from a 1.8-V supply.展开更多
A CMOS RF（radio frequency） front-end for digital radio broadcasting applications is presented that contains a wideband LNA,I/Q-mixers and VGAs,supporting other various wireless communication standards in the ultrawi...A CMOS RF（radio frequency） front-end for digital radio broadcasting applications is presented that contains a wideband LNA,I/Q-mixers and VGAs,supporting other various wireless communication standards in the ultrawide frequency band from 200 kHz to 2 GHz as well.Improvement of the NF（noise figure） and IP3（third-order intermodulation distortion） is attained without significant degradation of other performances like voltage gain and power consumption.The NF is minimized by noise-canceling technology,and the IP3 is improved by using differential multiple gate transistors（DMGTR）.The dB-in-linear VGA（variable gain amplifier） exploits a single PMOS to achieve exponential gain control.The circuit is fabricated in 0.18-μm CMOS technology.The S11 of the RF front-end is lower than -11.4 dB over the whole band of 200 kHz-2 GHz.The variable gain range is 12-42 dB at 0.25 GHz and 4-36 dB at 2 GHz.The DSB NF at maximum gain is 3.1-6.1 dB.The IIP3 at middle gain is -4.7 to 0.2 dBm.It consumes a DC power of only 36 mW at 1.8 V supply.展开更多
文摘在无线接收机中,天线接收的信号强度往往变化很大,自动增益控制环路(automatic gain control,AGC)根据这个信号强度来动态调节控制放大器的增益,向后级基带电路(如ADC)提供幅度恒定的信号,使得接受到的不同强度信号均能被正确接收和解调;为了达到通过识别接收机接收信号的强度动态调节放大器的增益,以实现输出信号幅度恒定的目的,文章基于TSMC90nm CMOS工艺着重论述了针对70 MHz中频信号的AGC电路设计过程,详细设计了AGC各模块电路,并从提高线性度、降低直流失调和提高稳定性等方面对电路进行了优化,主要介绍AGC芯片的版图设计并进行了后仿,给出了整个AGC系统的工作特性和各项指标;在电路设计过程中,针对线性度、输出信号幅度、增益控制范围等进行改进与优化,得到符合设计指标的电路结构;最后对AGC环路的性能进行仿真验证,得到该AGC在满足输出信号幅度和线性度的基础上达到了30dB的动态范围,满足了接收机系统的要求。
文摘A CMOS variable gain amplifier（VGA） that adopts a novel exponential gain approximation is presented.No additional exponential gain control circuit is required in the proposed VGA used in a direct conversion receiver.A wide gain control voltage from 0.4 to 1.8 V and a high linearity performance are achieved.The three-stage VGA with automatic gain control（AGC） and DC offset cancellation（DCOC） is fabricated in a 0.18-μm CMOS technology and shows a linear gain range of more than 58-dB with a linearity error less than ±1 dB.The 3-dB bandwidth is over 8 MHz at all gain settings.The measured input-referred third intercept point（IIP3） of the proposed VGA varies from-18.1 to 13.5 dBm,and the measured noise figure varies from 27 to 65 dB at a frequency of 1 MHz.The dynamic range of the closed-loop AGC exceeds 56 dB,where the output signal-to-noise-and-distortion ratio（SNDR） reaches 20 dB.The whole circuit,occupying 0.3 mm^2 of chip area,dissipates less than 3.7 mA from a 1.8-V supply.
文摘A CMOS RF（radio frequency） front-end for digital radio broadcasting applications is presented that contains a wideband LNA,I/Q-mixers and VGAs,supporting other various wireless communication standards in the ultrawide frequency band from 200 kHz to 2 GHz as well.Improvement of the NF（noise figure） and IP3（third-order intermodulation distortion） is attained without significant degradation of other performances like voltage gain and power consumption.The NF is minimized by noise-canceling technology,and the IP3 is improved by using differential multiple gate transistors（DMGTR）.The dB-in-linear VGA（variable gain amplifier） exploits a single PMOS to achieve exponential gain control.The circuit is fabricated in 0.18-μm CMOS technology.The S11 of the RF front-end is lower than -11.4 dB over the whole band of 200 kHz-2 GHz.The variable gain range is 12-42 dB at 0.25 GHz and 4-36 dB at 2 GHz.The DSB NF at maximum gain is 3.1-6.1 dB.The IIP3 at middle gain is -4.7 to 0.2 dBm.It consumes a DC power of only 36 mW at 1.8 V supply.
