A high-Q and wide-dynamic-range 70 MHz CMOS bandpass filter for wireless receivers

Abstract

Design of a sixth-order CMOS high--bandpass filter with automatic tunning for channel selection in wireless receivers is presented. A linearized transconductance ( ) cell is designed and optimized for both noise and linearity. The cells of the biquads and of the tuning circuitry are implemented using unitcells for better matching and less power consumption. The filter prototype achieves a measured bandwidth of 200 kHz at 70 MHz ( = 350). The measured input equivalent noise is 81 nV/ Hz and the IIP 3 is 10 dBm, which corresponds to a dynamic range of about 66 dB. At 2.5 V, the total power consumption is 120 mW.

A low power RC time constant auto-tuning circuit for RC-integrators in high linearity continuous-time delta sigma modulators

“…The principles, advantages, and drawbacks of both active gm and passive tuning schemes have been analyzed and compared in [2]. Although active transconductance gm tuning can provide a high accuracy better than 1% [3]- [7], it suffers from non-linearity [8], [9], large silicon area and high power consumption. In the passive components calibration, for the same accuracy setting the passive C tuning is better because its frequency response is much better compared to the passive R tuning [10].…”

An accurate automatic tuning scheme for high-Q continuous-time bandpass filters based on amplitude comparison

“…Several automatic-tuning methods for second-order bandpass filters have been proposed. The frequency tuning methods have been reported to achieve tuning error less than 1% [1]- [6]. However, Q-tuning at high frequency ( 100 MHz) is still a big challenge.…”

“…However, mismatch of the peak detectors will cause the gain control error, thus, the Q-tuning error. Another Q-tuning method [4], [6] uti-Manuscript received April 8, 2002;revised February 11, 2003 lizes the least-mean-square algorithm to lock the filter's gain, where Q-tuning error of 1% is reported for a 10.7 MHz OTA-C bandpass filter. An accurate high-frequency divide-by-Q circuit is necessary to define the Q-factor in this method, but the proposed capacitive voltage divider is vulnerable to parasitic and loading capacitance.…”

Low-distortion low-voltage operational transconductance amplifier

“…The OTA is simulated in a standard TSMC 0.18 mm CMOS process with a 1.8 V supply voltage. The simulation results show that the total harmonic distortion of the proposed OTA is less than 1% up to 0.85 Vp-p.Introduction: Recent research shows a high demand for highly linear operational transconductance amplifiers (OTAs) with an aim to reduce total harmonic distortion (THD) [1][2][3][4]. However, most of these linearisation techniques may present important drawbacks such as reduced effective transconductance and significant power consumption.…”