Nauta's Transconductor Research Articles

G<sub>m</sub>-C Complex Band-Pass Filter with Tuning Circuit in 0.18μm CMOS

This paper presents a 0.18μm CMOS based Gm-C complex band-pass (CBP) filter with tuning circuit. Active-Gm-C structure with Nauta transconductor and phase-locked loop (PLL) architecture are adopted by the filter and the tuning circuit respectively which can achieve accurate frequency response. The layout size is 970μm×920μm. Under a 1.8V supply voltage, measurement results show that the pass-band gain and the ripple of the filter is 3.1dB and 3dB respectively. The bandwidth after tuning is 32.5MHz, image rejection ratio (IRR) is about 47dB, and the power dissipation of the filter is about 21.6mW.

On the use of Nauta's transconductor in low-frequency CMOS g/sub m/-C bandpass filters

This paper discusses the use of a transconductor, first proposed by Nauta for high frequency applications, in low frequency CMOS g/sub m/-C bandpass filters. The behavior of the transconductor is examined in detail, showing that the robust implementation of higher-order low-voltage filters is possible for center frequencies in the lower megahertz region. The experimental results are presented of the realization of two prototypes, a 0.6-/spl mu/m CMOS 18th-order real bandpass filter and a 0.35-/spl mu/m CMOS 7th-order complex (14th-order bandpass) filter, both with a center frequency of 3 MHz and a passband of 1 MHz. These filters comply with the specifications for the channel-select stage of the Bluetooth short-range radio receiver.