Low-power baseband filter for zero-intermediate frequency digital video broadcasting terrestrial/handheld receivers

Digital video broadcasting terrestrial (DVB-T) is being adopted bymany countries all over theworld. Recently, DVB-H, a new standard compatible with DVB-T, has been proposed for handheld terminals, which demands low power consumption. In this study, a continuous-time filter for DVB-T/H receivers is presented. High linearity and lownoise are achieved by selecting a Gm-C filter topology implemented with a novel programmable transconductor based onMOS transistors in the triode region. The filter is tunable in a wide range, which makes it suitable for VLSI integration. The filter has been designed in a standard 0.5 μm CMOS technologywith a single 3.3 Vsupply voltage. Experimental results show an IM3 of 258 dB for a two tone experiment with 2 Vpp output signal centred at 2 MHz.     

A Tunable Pseudo-Differential OTA With $-78~{hbox {dB}}$ THD Consuming 1.25 mW

A novel linear tunable transconductor based on a combination of linearization techniques is presented. The input signal is transferred to the V-I conversion element by means of a high-speed feedback loop. Then, the linear V-I conversion is accomplished using quasi-floating-gate MOS transistors biased in the triode region. Finally, the absence of current mirrors in the signal path provides low sensitivity to transistor mismatch and reduces the harmonic distortion. The operational transconductance amplifier (OTA) was fabricated in a 0.5-mum CMOS technology with a single 3.3-V supply voltage. Experimental results show a total harmonic distortion of -78 dB at 1 MHz with 1-V_pp input signal. High linearity of the OTA is obtained over a two octave tuning range with only 1.25-mW power consumption.     

CMOS linear programmable transconductor suitable for adjustable Gm-C filters

A novel CMOS linear programmable transconductor is presented. It is based on a telescopic cascode operational transconductance amplifier with source degeneration implemented by means of highly linear tunable active resistors. The transconductor has been designed in a 0.5 mum CMOS technology featuring a third-order intermodulation (IM3) of -54.8 dB at 10 MHz for a 1 V_pp output voltage. Its feasibility for Gm-C filter design has been experimentally validated with a 1 MHz tunable third-order Chebyshev lowpass filter suitable for Bluetooth applications.