US 4,896,374 AGranted

Broadband monolithic balanced mixer apparatus

AssigneeSiemens Aktiengesellschaft

InventorsRaymond M. Waugh, Tzu-Hung Chen, Mahesh Kumar

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Abstract

A broadband monolithic balanced mixer employs a unidirectional active 180.degree. hybrid. The hybrid is fabricated utilizing two active signal splitters, two all pass phase shifting networks and two active signal combiners. The all pass networks provide a controlled phase response while the absolute phase of the network varies with frequency whereby the frequency difference between the two networks remains constant at 180.degree. over a very broad frequency range. Because the phase varies with frequency, the source and load impedance are rendered equal and resistive. Thus the above-described apparatus employs a common source FET with feedback for the signal splitter and a common gate FET for the combiner. Matching networks are used at all four ports of the active hybrid to achieve the desired match over the desired frequency ranges. The outputs of the hybrid are applied to suitable mixer circuits including FET or diode devices.

Claims20

Dependent claims

A broadband monolithic balanced mixer apparatus for use within the microwave frequency ranges, comprising:

an active hybrid means having one input adapted to receive an RF signal and another input adapted to receive a local oscillator (LO) signal to provide at first and second outputs a combined LO and RF signal, said active hybrid means having a first active signal splitter having an input coupled to said one input for receiving said RF signal and having first and second outputs, a second active signal splitter having an input coupled to said another input for receiving said LO signal, said second splitter having first and second outputs,
a first active signal combiner having a first input coupled to said first output of said first signal splitter and having a second input and an output,
a second active signal combiner having a first input coupled to said second output of said first splitter and having a second input and an output,
a first all pass network having an input and an output terminal, with said input coupled to said first output of said second splitter and with said output coupled to said second input of said first combiner,
a second all pass network having an input and an output, with the input of said second all pass network coupled to said second output of said second splitter and with the output of said second all pass network coupled to the second input of said second combiner, wherein the output of said first and second combiners each provide an RF/LO signal of a different phase with respect to one another, and
mixing means coupled to said outputs of said first and second combiners to provide at an output an IF signal being of a frequency equal to the difference between said RF and LO signal frequencies and substantially free of said RF and LO signals.

3 more elements

Dependencies are inferred from the claim text.