A 60-mW 200-MHz continuous-time seventh-order linear phase filter with on-chip automatic tuning system

Abstract

A full CMOS seventh-order linear phase filter based on-biquads with a 3-dB frequency of 200 MHz is realized in 0.35-m CMOS process. The linear operational transconductance amplifier is based on complementary differential pairs in order to achieve both low-distortion figures and high-frequency operation. The common-mode feedback (CMFB) employed takes advantage of the filter architecture; incorporating the load capacitors into the CMFB loop improves further its phase margin. A very simple automatic tuning system corrects the filter deviations due to process parameter tolerances and temperature variations. The group delay ripple is less than 5% for frequencies up to 300 MHz, while the power consumption is 60 mW. The third-harmonic distortion is less than 44 dB for input signals up to 500 mV pp. The filter active area is only 900 200 m 2. The supply voltages used are 1.5 V.

380 MHz low-power sharp-rejection active-RC LPF for IEEE 802.15.4a UWB WPAN

“…From (2), the cut-off frequency (ω cutoff ), Q factor and gain (H) of the Biquad are determined by R and C values as Due to the tradeoff between the current consumption and gain, to have high gain with a given limited amount of current, a cross connection at the PMOS load transistors M 5,6 is adopted. This cross connection creates the negative transconductance (-g mc ) which compensate positive g mp of the diode connected PMOS and g ds of M 3,4 .…”

“…For wideband LPF, Gm-C LPF is often used but it is limited in linearity, dynamic range and sensitive to parasitic [5]. Previous published works of active RC LPF are often for narrow band applications, most papers show the cutoff frequency in the range of a hundred MHz are gm-C type [6]- [9].…”

Bandwidth - Power Optimization Methodology for SFB Filter Design

“…However, since high power consumption is not appropriate in the mobile era, achieving both high-band and low power consumption in filter design is an important challenge at present [15]. G m -C filters have been popularly [1][2][3][4][5][6][7] used for wideband filter design due to their wideband characteristic, which in turn stems from their open loop characteristic. In this structure, transconductance (G m ) cells are used to implement resistors and inductors.…”

A 2V 0.25μm CMOS 250MHz Fully-differential Seventh-order Equiripple Linear Phase LF Filter

“…For these reasons OTA-C filters have become the preferred choice for filtering tasks in mixed-signal ICs. In recent years, several integrated continuous-time filters with high frequency range and low power consumption have been realized successfully and used for read/write channels in hard disk drive systems [2][3][4][5][6][7][8][9]. Most of the filters are based on the cascade structure.…”

“…Equation (9) shows that the transconductance of the proposed OTA is linear and tunable by varying bias voltage.…”