Integrated wideband and low phase‐noise signal source using two voltage‐controlled oscillators and a mixer

Abstract

This study presents a method to design a wideband signal source based on two voltage‐controlled oscillators (VCOs) with different centre frequencies and a mixer. The principle is to combine three frequency bands to form one wide frequency range. The three bands consist of second harmonic bands from two VCOs and a mixer band that is generated by mixing the two fundamental signals of VCOs to bridge the frequency gap. Apart from the wide tuning range, an additional benefit of a mixer‐based signal source is that the phase‐noise increases ∼3 dB/octave, which is less than the theoretical limit (6 dB/octave) for a fundamental frequency VCO followed by a frequency multiplier or extraction of second harmonic signal from a VCO. A prototype of the proposed signal source implemented in indium gallium phosphide hetero junction bipolar transistor monolithic microwave integrated circuit technology demonstrates both wide frequency tuning range and a very low phase noise. It exhibits a tuning bandwidth extending from 11.8 to 16.7 GHz and the signal's phase noise varies between −91 and −103 dBc/Hz at 100 kHz offset frequency.

A Ku-band wide-tuning-range high-output-power VCO in InGaP/GaAs HBT technology

“…It can be seen that the presented VCO has a lower FOM TVP , which suggests that the VCO achieves wide tuning range and high output power as well as other excellent properties. Note that the higher TR reported in Reference [5] was achieved. However, its variation of tuning voltage 13 V is much bigger than supply voltage 5 V, which is not commonly used, because this could shorten the practical time of the devices.…”

“…It features a minimum drawn emitter width of 1 m and f T /f max of 65/80 GHz. The process offers four types of npn transistors, Q1H051B1, Q1H101B1, Q1H151B1 and Q1H201B1, with different emitter length (5,10,15 and 20 m, respectively) and with breakdown voltages of 9 V. Two metal layers, two types of capacitors, resistors, varactor diodes, as well as inductances are available. Two thicknesses of GaAs substrates (75 and 100 m) can be chosen.…”