DESIGN OF CMOS BASED FM MODULATOR USING 90NM TECHNOLOGY ON CADENCE VIRTUOSO TOOL

Abstract

This work shows implementation of a radio frequency (RF) CMOS transmitter operating around 8 GHz, in a constant- envelope frequency - domain approach  named Frequency Modulation in Ultra-Wideband (FM-UWB) and implemented using 90nM CMOS technology. Both the two main transmitter circuits are relaxation oscillator type blocks. The circuit is in ductorless; hence it is wideband tunable and saves large area. In this transmitter the triangular signal is also
present that can be used advantageously. The control circuit helps to obtain an FSK oscillator which generates a triangular signal with two different oscillation frequencies. The D flip-flop power dissipation is 15.62 u W. It is controlled by the transmitted data. Also, by use of only MOS varactors, a VCO capable of achieving 1 GHz of tuning range bandwidth was implemented with the operating frequency around 8 GHz. VCO operating voltage 1 V with power consumption 12uW.
In the implementation of the transmitter the basic blocks used are Buffer, D flip-flop, Relaxation oscillator for implementing VCO and carrier generation, and transmission gates. And at last, thelayout is also drawn using Cadence Virtuoso Tool in 90 nm technology. The area of layout implemented is 0.0716 mm2 Simulations results are quite satisfactory. The circuit fulfills the desired goals of obtaining a low-power and low-cost transmitter, which is capable of achieving
high data rates and uses already occupied RF transmission bands.