A low-power high-frequency all-pass-filter-based sinusoidal quadrature oscillator using CMOS current mirrors

A low-power high-frequency sinusoidal quadrature oscillator is presented through the use of two all-pass current mirror (CM)-based filters, a 1st-order CM low-pass filter and a CM bilinear transfer function. The bilinear transfer function is described in terms of a negative resistance (R_N = -R_L) where R_L is a resistor load of a current mirror. The technique is relatively simple based on (i) inherent time constants of current mirrors, i.e. the internal capacitances and the transconductance of a diode-connected NMOS, (ii) a simple negative resistance R_N formed by a resistor load R_L of a current mirror. Neither external capacitances nor inductances are required. As a particular example, a 1.01-GHz, 0.6-mW, 2-V CMOS all-pass-filter-based all-current-mirror sinusoidal quadrature oscillator is demonstrated in this paper. The oscillation frequency (f₀) is 1.01 GHz and is current-tunable over a range of 400 MHz or 40%. The power consumption is at approximately 0.6 mW. The amplitude matching and the quadrature phase matching are better than 0.05 dB and 0.15deg, respectively. Total harmonic distortions (THD) are less than 0.5%. At 2 MHz offset from the 1.01 GHz, the carrier to noise ratio (CNR) is 83.01 dBc/Hz whilst the figure of merit called a normalized carrier-to-noise ratio (CNR_norm) is 139.29 dBc/Hz. The ratio of the oscillation frequency (f₀) to the unity-gain frequency (f_T) of a transistor is 0.134.