Method and apparatus for generating non-linear variable impedance

Abstract

An impedance-generating device that provides a resistance and a reactance that are non-linear functions of a signal over a wide impedance range (VariablE Non-Linear Impedance Circuit Electronics, 'VENICE'). An electronic component that has a gain characteristic with a unity gain frequency that is directly proportional to that signal can be configured to generate such an impedance. Such an electronic component configured to provide a negative effective resistance and a variable non-linear reactance can be used to implement a high frequency harmonic generator. This generator can provide high order harmonics which can be used in high frequency communications systems. The electronic component can also be configured to provide only a voltage-variable non-linear reactance which can be used to implement a reactive mixer to frequency shift a high frequency signal to an intermediate frequency signal, from mixing the high frequency signal with a local oscillator signal. This mixer provides a gain, at the intermediate frequency, that is the unity gain frequency of the electronic component divided by the intermediate frequency. Two stages of such mixers can be used in a homodyne circuit to generate the intermediate frequency signal without the use of off-chip bandpass filters. Also, an amplification to the intermediate frequency signal generated by the mixing can be used to implement a RF amplifier from the further modulation of this intermediate frequency signal on the local oscillator signal. These impedance-generating devices can thus implement high performance electronic circuits for communications applications.