Digital Controlled Oscillator
A monolithically integrated, digitally controlled oscillator is presented. It has an output frequency range from 18.9 Hz to ≫ 20 MHz, the long term stability of a quartz oscillator and a short term clock edge uncertainty with a standard deviation of 0.4 ns. The digital frequency control is fully linear with a resolution of 18.9 Hz. The only required external component is a reference quartz. The circuit operates from a single 5 V power supply and is fabricated in a 1.5 ¿m, double metal, single poly, CMOS process. The chip area is 4.1 mm2.
A digital frequency synthesizer
A digital frequency synthesizer has been designed and constructed based on generating digital samples of \exp [j(2^{\pi}nk/N)] at time nT . The real and imaginary parts of this exponential form samples of quadrature sinusoids where the frequency index k is allowed to vary (-N/4) \leq K . The digital samples drive digital to analog converters followed by low-pass interpolating filters to produce analog sinusoids. The method is superior to digital difference equations with poles on the unit circle since the noise or numerical inaccuracy remains bounded. The digital technique used consists of factoring the exponential into two table look-ups from an efficiently organized small READ-ONLY memory table and performing a complex multiply to produce the real and imaginary components. A small array multiplier efficiently organized performs the multiplications. The technique lends itself to the production of phase coherent or phase controlled sinusoids because of the indexing arrangement used. In addition finer frequency steps than the READ-ONLY memory allows are available by expanding the indexing register at no increase in inaccuracy.
Frank Must Marry Money: Men, Women, and Property in Trollope's Novels
There is a continuing debate about the extent to which women in the 19th century were involved in economic life. The paper uses a reading of a number of novels by the English author Anthony Trollop...