A very wide bandwidth digital VCO using quadrature frequency multiplication and division implemented in AlGaAs/GaAs HBT's

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 exclusiveOR (XOR) circuit was developed which uses product pairs and emitter-coupled logic. To achieve the highest performance possible, the critical path is symmetric and special physical design techniques were developed to promote matched-capacitance. The maximum measured frequency was 13.66 GHz. The chip occupies 1.9 mm 1.6 mm and dissipates 2.45 W at a supply voltage of 6.0 V. With a measured frequency range from 1.25 to 13.66 GHz, this circuit has the widest bandwidth reported in the literature for any VCO, digital or analog.