二次变频

二次变频的本振信号由PLL的输出信号经整数分频得到。

The second local frequency signal is provided by an integer-divider after PLL output .

基于0·18μMRFCMOS工艺，采用双端调谐结构实现了一种可应用于WLAN的二次变频收发机的压控振荡器。

A monolithic LC-tuned voltage controlled oscillator ( LC-VCO ) with 2 tuning terminals is designed for a dual frequency conversion transceiver for WLAN and realized using 0.18 μ m radio frequency ( RF ) CMOS technology .

本模块接收机设计采用超外差二次变频，主要由低噪声放大器、调谐滤波器、混频器、中放电路和AGC控制电路等几部分组成，实现了大动态范围接收技术指标。

Using superheterodyne second frequency conversion , this module receiver design is composed of LNA , tuned filter , mixer , IF amplifier circuit and AGC control circuit to implement large dynamic range receive technical criteria .

对接收机的多种类型的优点与缺点进行了分析与比较，提出了采用二次变频方案来设计EMI接收机的思路，并给出了粗略框图。

The advantages and disadvantages of the different types of receivers are also analyzed and compared , on the basis of which an idea of designing EMI receivers through two-time frequency conversion is put forward and a rough frame diagram is given .

本文采用二次变频结构（GPS/Galileo模式下低中频为27.5MHz，GLONASS模式下为21MHz），经组合和多相滤波器分别实现信号分离和抑制镜像。

This paper chooses the structure of two-times frequency converting ( with low frequency 27.5 MHz in GPS / Galileo mode , with 21 MHz in GLONASS mode ), by the combinations and multi-phase filter to achieve separation and image suppression .

为实现宽带工作，接收机采用了超外差结构中的二次变频方案进行设计，第一中频为高中频。

The high-intermediate-frequency superheterodyne structure with dual-conversion is used in the receiver to realize the wideband receiving .

该电路采用二次变频低中频结构，集成了低噪声放大器、上变频混频器、下变频混频器等模块。

An RF front-end circuit for a fully integrated CMOS DTV tuner is presented in this paper , where double-conversion low IF architecture is employed .

根据课题的技术指标的要求并考虑到现有器件水平，系统采用了超外差二次变频的体系结构。

According to the technical indicators issues and taking into account the requirements of existing devices , the system uses double-conversion of the superheterodyne architecture .

研究了一体化二次变频收发信机中各种组合频率干扰的产生原因：主要是由于混频器和放大器的非线性。

This paper investigates various combined frequency interference in integrated and double-converted transceivers , and points out that the reason is the non-linearity of frequency mixer and amplifier .

最后给出了降低组合频率干扰电平的几种途径，对提高一体化二次变频收发信机的电磁兼容性进行了有益探讨。

Finally , several approaches are described to decrease the combined frequency interference level , and some ideas are discussed to improve the EMC capability of integrated and double-converted transceiver .

对该新方案进行了理论分析，进而对这种改进二次变频方案提出了采用的频率配置关系和中频滤波器参数设计准则，并结合一个工程实例完成了相关设计。

Based on the theory analysis of this scheme and an engineering example , formula of frequency planning and design rules of intermediate frequency filter ′ s parameter are proposed .

对于前者，主要阐述如何将超外差技术和正交混频结合起来，利用二次变频实现宽带接收和镜频抑制；对于后者，主要介绍带通采样定理和基于多相均匀滤波器组的数字信道化方法。

For the former , through combining the superheterodyne method and the quadrature mixing frequency method , the wideband reception and mirror frequency suppression can be implemented by Secondary frequency conversion technology .

另外还设计了一种符合二次变频结构要求的单环双输出锁相频率合成器，仿真分析了电荷泵、环路损耗、环路带宽等环路参数的选择对环路的影响。

Then discuss the theory of PLL and synthesizer , and design a synthesizer for used in the twice frequency conversion framework Repeater . Also analyzed the effect for changing the parameters of loop .

冷冻水系统为二次泵系统，二次泵采用变频调速器变流量控制；

Control secondary chilled water pumps with frequency converter .