A 54–862-MHz CMOS Transceiver for TV-Band White-Space Device Applications

Abstract

A 54-862-MHz single-chip CMOS transceiver with a single LC voltage-controlled oscillator (VCO) fractional- <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> synthesizer is developed for TV-band white-space communications and cognitive radio applications. The transceiver is based on a single-conversion zero-IF architecture with integrated harmonic filtering capability. A combined harmonic rejection mixer and coarse RF tracking filter significantly lessens the in-band harmonic emission problem in the transmitter, as well as the harmonic mixing problem in the receiver. A fractional- <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> phase-locked loop (PLL) with only a single LC VCO and a wideband multimodulus local oscillator (LO) generator seamlessly covers the entire band. A wideband semi-dynamic divide-by-1.5 circuit is adopted in the LO generator to reduce the VCO tuning range requirement by 25 %. A pseudoexponential capacitor bank structure in the LC VCO substantially reduces the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">VCO</sub> and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">step</sub> variations across the total band, which is beneficial for maintaining the PLL loop stability and dynamics over the wide band. The transceiver is implemented in 0.18-μ m CMOS, and operates with a single 1.8-V supply. The transmitter delivers a nominal output power of -3 dBm, and exhibits OP <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1 dB</sub> of >; +6.4 dBm, OIP <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> of >; +15.9 dBm, and error vector magnitude (EVM) of <; -34.7 dB for 64-QAM signal. The image and carrier leakage calibration circuits suppress the leakage components below -41 dBc across the entire band. The receiver achieves about 100-dB gain dynamic range, 3.5-6.9-dB noise figure, <; -29-dB EVM, and -43.4/-59.7-dBc third/fifth harmonic mixing suppression. The synthesizer and LO generator achieves the integrated phase noise <; 0.8 rms degree over the entire band.