A high-bandwidth voltage controlled oscillator (VCO) with a frequency-multiplied/divided range of 0.25-20 GHz implemented in a GaAs HBT process

A high speed voltage-controlled oscillator (VCO) bas been developed using 50 GHz GaAs-AlGaAs HBTs which can generate differential signals in the range of 0.25-20 GHz. The design process was focused on producing a layout with highly-matched parasitic capacitance by exploiting the high degree of symmetry present in differential circuits. The system design and cell layout techniques are described in detail using examples from the VCO. The operation of the VCO is also discussed along with design tradeoffs.