Order Elliptic Low-pass Filter Research Articles

Fuzzy Adaptive Modified PSO Algorithm Assisted to Design of Six Order Elliptic Low Pass Filter

To provide cost-effective communication systems for separate a signal into different frequency region and eliminate adverse signals and harmonics, Fuzzy Adaptive Modified particle swarm optimization (FAMPSO) method was used to have an optimized gain ripple of 6 th order elliptic low pass filter with 300 MHz cut-off frequency. The feasibility and effectiveness of the FAMPSO algorithm is demonstrated and results are compared with PSO algorithm. It is shown that FAMPSO has high quality solution, superior convergence characteristics and shorter computation time.

칩 인덕터를 사용하여 광대역 저지 특성을 갖는 소형 C-밴드 Semi-Lumped 저역 통과 여파기

칩 인덕터를 이용하여 넓은 저지 대역과 소형화 특성을 갖는 C-밴드 semi-lumped 저역 통과 여파기를 제안하였다. 칩 인덕터의 자기 공진 주파수(SRF: Self Resonance Frequency) 특성을 유지하기 위하여 추가된 분리형 인덕터와 SRF 특성으로 인해 발생되는 감쇠 폴을 이용하여 광대역 저지 대역과 높은 저지 특성을 얻을 수 있었다. 3차 elliptic function 여파기에 칩 인덕터(L: 9.1 nH, SRF: 5.5 GHz, Q: 25)를 적용한 결과, 마이크로스트립 라인 인덕터로 구현한 여파기보다 크기가 37.4 % 감소하였으며, 삽입 손실이 0.38 dB, 차단 주파수는 920 MHz, 1.43~7.8 GHz의 넓은 저지 대역(20 dB 이하) 특성을 가졌다. The C-band semi-lumped lowpass filter with broad stopband and compact size characteristic using chip inductor is proposed. To provide an additional attenuation pole in stopband by SRF, a separable inductor is added to proposed structure, and it has broad stopband characteristic. The third order elliptic function lowpass filter with chip inductor(L: 9.1 nH, SRF: 5.5 GHz, Q: 25) has insertion loss of 0.38 dB, cutoff frequency of 920 MHz, broad stopband(below 20 dB) of 1.43~7.8 GHz and the size is reduced 37.4 % compared to distributed inductor.

A low power 8th order elliptic low-pass filter for a CMMB tuner

This paper presents an 8th order active-RC elliptic low-pass filter (LPF) for a direct conversion China Mobile Multimedia Broadcasting (CMMB) tuner with a 1 or 4 MHz −3 dB cutoff frequency (f−3dB). By using a novel gain-bandwidth-product (GBW) extension technique in designing the operational amplifiers (op-amps), the proposed filter achieves 71 dB stop-band rejection at 1.7 f−3dB to meet the stringent CMMB adjacent channel rejection (ACR) specifications while dissipates only 2.8 mA/channel from a 3 V supply, its bias current can be further lowered to 2 mA/channel with only 0.5 dB peaking measured at the filter's pass-band edge. Elaborated common-mode (CM) control circuits are applied to the filter op-amp to increase its common-mode rejection ratio (CMRR) and effectively reject the large signal common-mode interference. Measurement results show that the filter has 128 dBμVrms in-band IIP3 and more than 80 dB passband CMRR. Fabricated in a 0.35-μm SiGe BiCMOS process, the proposed filter occupies a 1.19 mm2 die area.

Current-Mode Temperature Compensated Continuous-Time CMOSTransconductance-C Filter

In this paper a low voltage low power current-mode continuous-time low-pass filter is presented. The current-integrator is constructed of a multi-output linearized transconductance element driven by a balanced transimpedance amplifier. A 1 MHz third order elliptic low pass filter is designed and fabricated with the proposed current-mode integrator. The measurements show capability of operation with down to a 3 V supply voltage. The measured current consumption is 850 µA at room temperature and the dynamic range is 66 dB. The distortion of the filter is below 50 dBc with peak signal levels up to twice the quiescent current level and with the refined designs even lower distortion is expected. The filter uses a CMOS-current reference for temperature and process variation stabilization with a measured corner frequency temperature coefficient of −100 ppm/K.

Feasible designs for high order switched-current filters

Fully balanced Euler integrators featuring S/sup 2/I cells and common-mode rejection are used to realise ladder derived switched-current filters, based on modified left- and right-decomposition matrix methods. The usual problems of large silicon area, high sensitivity and component spreads, encountered in very high order designs, are overcome by minimising the input circuitry and by adopting modified approximation and prototype ladder manipulation techniques. The example of a 6th order modified left-UL bandpass filter demonstrates improved sensitivity, and a 21st order elliptic lowpass filter achieves a spread of 13.63, while preserving low passband sensitivity.

A scalable high-performance switched-capacitor filter

Switched-capacitor filters tend to display reduced performance when implemented at reduced feature size because of higher KT/C and 1/f noise, and reduced operational amplifier gain and swing. This paper describes some circuit solutions to certain performance degradations associated with technology scaling, including chopper stabilization, and class AB differential operational amplifier architecture. An experimental fifth order elliptic PCM low-pass filter, using 3 \mu CMOS technology, achieved an area of 200 mil^2 per pole. Typical measured results for a \pm 2.5-V power supply are: a dynamic range of 87 dB, a power supply rejection ratio (PSRR) of 40 dB over 1-MHz range.

A frequency-locked adaptive filter

A frequency-locked RC active ladder filter is described, which is frequency-locked to a sinusoidal control tone. The tunable ladder filter is used as a frequency discriminator by using two of the filter branch voltages to generate a control voltage. The control voltage is then used to tune or frequency-scale the ladder filter transfer function to lock the filter to the frequency of the control tone. A simple linear frequency-signal control system is developed to describe the frequency-locked performance of the adaptive filter. The frequency-locked filter can be designed so that the sinusoidal control tone is rejected at the filter output, making it possible to adapt the filter transfer function during transmission of a message. A practical frequency-locked filter is given in which a frequency-locked third order elliptic lowpass filter is designed. The performance of the practical filter is analysed using a simple linear control system model.