A VERY WIDE BANDWIDTH DIGITAL VCO USING QUADRATURE FREQUENCY MULTIPLICATION AND DIVISION IMPLEMENTED IN ALGAAS GAAS HBTS/

A digital voltage-controlled oscillator (VCO) is described which uses frequency multiplication and division to achieve very wide bandwidth, The VCO uses current-mode logic and does not require reactive elements such as inductors, capacitors or varactors, A novel, fully symmetric exclusive-OR (XOR) circuit was developed which uses product pairs and emitter-coupled logic, To achieve the highest performance possible, th e critical path is symmetric and special physical design techniques we re developed to promote matched-capacitance The maximum measured frequ ency was 13.66 GHz. The chip occupies 1.9 mm x 1.6 mm and dissipates 2 .45 W at a supply voltage of -6.0 V, With a measured frequency range f rom 1.25 to 13.66 GHz, this circuit has the widest bandwidth reported in the literature for any VCO, digital or analog.