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By utilizing the first order behavior of the device, an equation for the frequency of operation of the submicron CMOS ring oscillator is presented. A 5-stage ring oscillator is utilized as the initial design, with different Beta ratios, for the computation of the operating frequency. Later on, the circuit simulation is performed from 5-stage till 23-stage, with the range of oscillating frequency being 3.0817 and 0.6705 GHz respectively. It is noted that the output frequency is inversely proportional to the square of the device length, and when the value of Beta ratio is used as 2.3, a difference of 3.64% is observed on an average, in between the computed and the simulated values of frequency. As an outcome, the derived equation can be utilized, with the inclusion of an empirical constant in general, for arriving at the ring oscillator circuit’s output frequency.

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In this paper, we present a new design of phase frequency detector (PFD) without reset, such that the blind zone and dead zone issues in the phase locked loop are annihilated. The PFD is designed using transmission gate-based latches, which produce UP and DOWN pulses only when there is a distinct phase difference between the reference and divided frequencies. Thus, the continuous pulses that get produced by the conventional NAND gate-based latches are avoided, leading to reduced power consumption of the PFD. The charge pump makes use of an op-amp used as a buffer, to reduce the current mismatch. The loop filter used is of second order, and the voltage-controlled oscillator is of conventional current-starved type. The divider makes use of true single-phase clock latches. It was found that the phase locked loop with new design of PFD, compared with the conventional design, consumes 27% lesser power, and the lock time is decreased by 79%. In addition, it was found that the control voltage swing is reduced by 71%, which leads to much lesser spur content at the output of the voltage-controlled oscillator.KEYWORDS blind zone, charge pump (CP), dead zone, divider, loop filter, phase frequency detector (PFD), voltagecontrolled oscillator (VCO)