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A 2.1-GHz 1.3-V 5-mW fully integrated Q-enhancement LC bandpass biquad programmable in fo, Q, and peak gain is implemented in 0.35-μm standard CMOS technology. The filter uses a resonator built with spiral inductors and inversion-mode pMOS capacitors that provide frequency tuning. The Q tuning is through an adjustable negative-conductance generator, whereas the peak gain is tuned through an input Gm stage. Noise and nonlinearity analyses presented demonstrate the design tradeoffs involved. Measured frequency tuning range around 2.1 GHz is 13%. Spiral inductors with Qo of 2 at 2.1 GHz limit the spurious-free dynamic range (SFDR) at 31-34 dB within the frequency tuning range. Measurements show that the peak gain can be tuned within a range of around two octaves. The filter sinks 4 mA from a 1.3-V supply providing a Q of 40 at 2.19 GHz with a 1-dB compression point dynamic range of 35 dB. The circuit operates with supply voltages ranging from 1.2 to 3 V. The silicon area is 0.1 mm2.
Date of Publication: June 2003