Versatile multi-decade CMOS voltage-controlled oscillator with accurate amplitude and pulse width control

Abstract

A compact, versatile and very high speed approach for waveform generation is introduced. It generates triangle and square waveforms. The VCO has a very wide range of oscillating frequencies, from fractions of Hz to 30 MHz in 0.5 lm CMOS technology. The amplitude of the oscillations can be very precisely controlled. It has linear control over frequency, amplitude and pulse-width. It can be used in frequency, amplitude and pulse-width modulation applications as well as in the accurate piecewise linear waveform synthesis. Experimental results of a MOSIS CMOS AMI 0.5 lm technology test chip are presented that validate the proposed circuit.

A temperature stabilized CMOS VCO

“…As the substrate resistance shows a positive TC, from (5) it is evident that an LC oscillator biased at ZTC still demonstrates a linear negative TC.…”

“…Each segment induces eddy currents in other segments that cause series resistance to increase [11]. This phenomenon causes a further reduction in frequency according to (5). Effective capacitance constitutes the capacitance of the resonator as well as parasitic contributions from all reverse biased junctions shunting the inductor.…”

“…However, the use of amplitude control as a technique for improving immunity against process, voltage and temperature (PVT) variations is widely reported [1], [5][6][7].…”

Accurate Analysis and Design of Integrated Single Input Schmitt Trigger Circuits

“…The Schmitt trigger (ST) has been used in both analog and digital domains to improve the noise immunity of circuits, thanks to its programmable or hard-wired hysteresis characteristics [5][6][7][8][9][10][11]. This characteristic has been utilized in many CMOS circuit blocks including oscillators [12][13][14][15], input/output pads of integrated circuits [16,17], image sensors [18][19][20][21][22][23][24], triangular carrier-based PWM modulators [25], subthreshold SRAMs [26][27][28][29], CMOS transceivers [30][31][32][33][34], impedance-to-frequency converters [35], digital to analog converters (DACs) [36], neuron-based analog to digital converters (ADCs) [37][38][39], powerline communication systems [40], binary logic circuits (i.e., adders [41] and gates [42]), and sensors [43,44].…”

A CMOS voltage-to-frequency converter with output frequency range programmability

“…In particular, this quasi-digital approach is, at present, taking a leading role in sensor signal interface circuits within embedded microcontroller systems. As a result, and focusing on CMOS technology seeking for the capability of cointegration of sensors and sensor electronics both analogue and digital at minimum cost and size, several CMOS fully integrated smart sensors with frequency or period [3][4][5][6] output signal, or simplest voltage-to-frequency converters that transform the conditioned output sensor voltage into frequency [7][8] have been proposed to date. This paper describes the design of a 1.8V-0.18µm CMOS VFC circuit with programmable output frequency ranges.…”