C.C.D./C.M.O.S. transversal filter using switched-capacitor technique for signal detection

A fully integrated c.c.d. filter has been built with a low power consumption. The c.c.d. filter employs c.m.o.s. support circuits and switched-capacitor techniques for signal detection. The power consumption of the filter is 20 mW.     

Parasitics-insensitive switched-capacitor ladder filters

A simple method for designing parasitics-insensitive switched-capacitor (s.c.) ladder filters is described. The response of the s.c. filter is related to that of a continuous-time prototype circuit by the bilinear z-transform.     

Switched-capacitor bandpass filter based on simulation of canonical reactance sections

A design method is described for switched-capacitor filters. It is based on the simulation of doubly terminated reactance filters in a canonical tandem section configuration and using the bilinear s-to-z transformation between the frequency planes of the continuous-time reference filter and the discrete-time switched-capacitor filter. The switched-capacitor circuits are completely insensitive to parasitic capacitances. The method permits the switched-capacitor realization of the whole class of lossless two-ports.     

MOS switched-capacitor filters

In the past several years, much progress has been made in bringing the economies of integrated-circuit technology to bear on the realization of voiceband frequency selective filters. This paper will review one approach to this problem, the use of switched-capacitor techniques. The paper emphasizes the practical aspects of switched-capacitor filter design under the constraints imposed by MOS integrated-circuit technology. The basic operation of switched-capacitor filters is reviewed, followed by a discussion of the properties of the various circuit building blocks in MOS technology. Finally, a summary of several filter organizations which appear to be well suited to switched-capacitor implementation is presented.     

An integrated CMOS switched-capacitor bandpass filter based on N-path and frequency-sampling principles

A new combined switched-capacitor (SC) frequency-sampling N-path filter is presented, which allows the implementation of very narrow bandpass filters. The included frequency-sampling (FS) filter suppresses undesirable passbands of the SC N-path filter. The center frequency f/SUB m/ of the bandpass filter is identical to the circuit clock frequency f/SUB c/. Experimental results are presented for a CMOS SC frequency-sampling four-path filter with second-order filter cells, a center frequency of 1 kHz, and -3-dB passband bandwidth of 11.5 Hz.     

开关电容低通滤波器的设计

为了滤除信号中掺杂的高频噪声,设计一种六阶级联式开关电容低通滤波器,以数据采样技术代替传统有源RC滤波器中的大电阻,有利于电路的大规模集成。滤波器由双二阶子电路级联而成,电路中的电容值利用动态定标技术计算确定。用Hspice进行仿真验证,结果表明:开关电容低通滤波器能较好地对信号进行整形,其频率特性符合设计指标。     

Continuous-time common-mode feedback for high-speed switched-capacitor networks

This paper deals with the design of a continuous-time common-mode feedback (CMFB) for switched-capacitor networks. Its reduced input capacitance decreases the capacitive load at the output of the fully differential amplifier, improving its achievable gain-bandwidth (GBW) product and slew rate. This topology is more suitable for high-speed switched-capacitor applications when compared to a conventional switched-capacitor CMFB, enabling operation at higher clock frequencies. Additionally, it provides a superior rejection to the negative power supply noise (PSRR/sup -/). The performance of the CMFB is demonstrated in the implementation of a second-order 10.7-MHz bandpass switched-capacitor filter and compared with that of an identical filter using the conventional switched-capacitor CMFB (SC-CMFB). The filter using the continuous-time CMFB reduces the error due to finite GBW and slew rate to less than 1% for clock frequencies up to 72 MHz while providing a dynamic range of 59 dB and a PSRR/sup -/>22 dB. Both circuits were fabricated in 0.35-/spl mu/m CMOS technology.     

开关电容滤波器

开关电容滤波器是近年来新开发的一种MOS大规模集成电路。本文概述了开关电容滤波器的基本理论,解析方法,电路构成以及实现IC化时的实际问题。     

Auto-SC, an automated switched-capacitor ladder filter designprogram

The use of a switched-capacitor filter design program, Auto-SC, is discussed. The program can be used to design both single-ended and differential switched-capacitor filters by a number of different methods. Guidelines for designing switched-capacitor filters using Auto-SC are presented. The circuits designed by Auto-SC are in a format that is directly compatible with SWITCAP. A design example is included     

A MOS switched-capacitor ladder filter in SIMOX technology for hightemperature applications up to 300°C

This paper describes techniques and methods used to realize a seventh order switched-capacitor low pass filter in SIMOX technology. The filter has Bessel characteristic and a 3 dB-bandwidth of 20 Hz at a clock frequency of 100 kHz. Special design of transistors and transmission gates results in drastically reduced leakage currents at high temperatures. The power supply voltage of the switched-capacitor filter is 10 V. The temperature range is extended up to 300°C. Experimental results of the transistors, the transmission gates, the operational amplifier, and the complete filter are presented     

A multipurpose micropower SC filter

A design strategy for micropower switched-capacitor filters is presented and illustrated with the design of a multipurpose second-order section. The filter, realized in a double-poly 6-/spl mu/m CMOS process, consumes 237 /spl mu/W if it is used as an equalizer (f/SUB c/=90 kHz, -V/SUB DD/=3 V) and only 72 /spl mu/W if it is used as a bandpass filter for 8 channels (f/SUB c/=192 kHz, V/SUB DD/=3 V). The dynamic range of the filter is over 60 dB and the total chip area is 3.5 mm/SUP 2/, including bonding pads.     

A Single Chip Speech Synthesizer Using a Switched-Capacitor Multiplier

A single chip speech synthesizer was designed using a switched-capacitor multiplier to implement the LPC algorithm. The chip contains the LPC-10 filter, 20 kbit ROM, all control logic, a three-pole switched-capacitor low-pass filter, and an audio amplifier capable of driving a speaker directly. The chip was fabricated in 5 µm CMOS technology and is 218 mils on the side.     

Improved circuit elements for switched-capacitor ladder filters

A new switched-capacitor floating inductance simulation circuit which does not depend on matching of passive elements is presented. A switched-capacitor source termination circuit which functions as a sample-and-hold circuit for a filter is also described.     

Lowpass to highpass transformation in vis switched-capacitor filters

A z-transformation for the design of highpass switched-capacitor filters is considered, which refers to a properly designed lowpass filter. The possible switched-capacitor implementation uses the voltage inverter switch approach with fully differential SC recharging devices: therefore, a bilinear design is obtained which introduces one zero at ? = 0.     

A high-Q bandpass fully differential SC filter with enhancedtestability

This paper presents a low-cost testing approach for switched-capacitor filters. A design for testability (DfT) methodology is discussed, and a system-level architecture is proposed providing capabilities for an off- and on-line test as well as a built-in self-test (BIST). To prove the feasibility of this approach, it has been applied to a sixth-order high-Q bandpass switched-capacitor (SC) filter. The benefit is a significant testability enhancement without degrading filter behavior. Experimental results from a silicon prototype are also presented     

A z plane Lerner switched-capacitor filter

The design of a switched-capacitor filter that optimizes both amplitude and phase response simultaneously is described. Conceptually derived from a Lerner function, the filter architecture is efficient and simple.     

First-order, switched-capacitor, low-pass filter implemented with GaAs insulated-gate FET switches

The application of the GaAs insulated-gate FET in switched-capacitor circuits is demonstrated. This is achieved by constructing a first-order, switched-capacitor, low-pass filter from monolithic GaAs IGFET switches and discrete capacitors. Hysteresis in the FET characteristic is shown to be unimportant. FET switching is shown to be independent of the absolute level of the switching signal.<>     

A low-noise chopper-stabilized differential switched-capacitor filtering technique

Describes the implementation of a wide dynamic range voiceband switched-capacitor filter using a differential chopper-stabilized configuration. The noise behavior of switched-capacitor filters is discussed qualitatively, and the effects of the chopper stabilization on the noise performance is analyzed. Experimental results from a fifth-order low-pass voiceband prototype are presented.     

Switched-capacitor filters driven with very low voltage clock signals

It is well known that the switches of a very low voltage (1.5V) switched-capacitor filter in a standard CMOS process must be driven with a clock signal higher than the power supply, often generated on-chip. The authors present, however, a technique to implement very low voltage switched-capacitor filters with switches driven at the same very low voltages.<>     

一种磁通门传感器的选频放大电路设计

由单个运放和电阻、电容网络构成的传统磁传感器信号处理电路中的选频放大电路是一种多环反馈型带通滤波器,其拥有电路结构简单、可靠性高、成本低等特点,但由于电路中电阻、电容的值较大,不易于集成。基于将磁通门传感器微型化的目的,在已有的Hspice磁通门探头信号产生模型的基础上,提出了一种由双二阶模块级联的开关电容带通滤波器来实现选频放大的方法,运用互补开关技术和动态范围定标技术,提高了滤波器的精度。利用Hspice进行仿真验证,结果表明:3 V供电电压下,与用CMOS技术实现的传统模拟带通滤波器相比,开关电容带通滤波器能较好地将磁通门传感器中的二次谐波进行选择并放大。