Zero intermediate frequency output electric bridge microwave field effect transnistor balanced mixer
The present invention be a kind of can single chip integrated microwave signal frequency conversion parts.
Microwave mixer is the vitals in the microwave systems such as communication, radar, electronic instrument.The microwave field effect transnistor balanced mixer is owing to have higher conversion gain, and the rejection of local oscillator noise and image frequency component is subjected to paying attention to widely preferably.But in the metal-semiconductor field effect transistor balanced mixer of using, need electric bridge at rf inputs and realize that the level of radiofrequency signal and local oscillator input distributes and mutual isolation at present.Also need electric bridge at medium frequency output end and realize the addition of intermediate-freuqncy signal and the inhibition of local oscillator noise and image frequency component.These two electric bridges will occupy sizable area on chip, especially in low-converter, the frequency of intermediate frequency is lower, and the size of output electric bridge will be in a centimetre magnitude.Therefore, circuit is can't monolithic integrated.
The microwave field effect transnistor balanced mixer that the purpose of this invention is to provide a kind of zero intermediate frequency output electric bridge, because zero intermediate frequency output electric bridge, the area of circuit will greatly reduce, thereby just can realize that monolithic is integrated.
The present invention realizes that as follows the radiofrequency signal of this microwave field effect transnistor balanced mixer (RF) is divided into the signal that the two-way amplitude equates through first power splitter, adds to the input of two radio frequency input bridges respectively.Local oscillation signal (LO) is divided into the signal that the two-way amplitude equates through second power splitter, adds to the input of two radio frequency input bridges respectively.The first radio frequency input bridge phase shift is that output and the 1st field-effect transistor of 0 ° joins, the second radio frequency input bridge phase shift is that output and the 2nd field-effect transistor of 180 ° joins, the input of two field-effect transistors and filter joins, and obtains output signal by filter output.
The field-effect transistor balanced mixer of zero intermediate frequency output electric bridge is with two power splitters and electric bridge or only make radio-frequency input signals and local oscillation signal be divided into amplitude separately with two phase splitters to equate at rf inputs, two signals that phase place is opposite are added in respectively on two field effect body pipes.The direct addition of the output signal of two pipes need not intermediate frequency output electric bridge, can curb local oscillator and image frequency signal, obtains the intermediate frequency output signal of addition.By not needing intermediate frequency output electric bridge, and radio frequency and local frequency are significantly higher, and radio frequency input bridge size is less, and circuit significantly reduces (can reduce to below 1/10) in shared size on the chip, thereby just can monolithic integrated.
Below in conjunction with accompanying drawing in detail optimum implementation of the present invention is described in detail.First power splitter [1], second power splitter [2], the first radio frequency input bridge [3], the second radio frequency input bridge [4], first field-effect transistor [5], second field-effect transistor [6], matched impedance [7], [8], filter [9] in the accompanying drawing 1.Radio frequency number (RF) is divided into the signal that the two-way amplitude equates through first power splitter among the figure, add to the input of two radio frequency input bridges respectively, local oscillation signal (RF) is divided into the input that the equal signal of two-way amplitude adds to two radio frequency input bridges respectively through first power splitter.Local oscillation signal (LO) is divided into the signal that the two-way amplitude equates through second power splitter, and the signal that amplitude equates adds to the input of two radio frequency input bridges respectively.Two outputs that is to say first power splitter [1] and second power splitter [2] intersect with the input of second radio-frequency bridge [4] with the first radio frequency input bridge [3] respectively and are connected, the first radio frequency input bridge [3] and the second radio frequency input bridge [4] respectively have an output through matched impedance ground connection, radio frequency input bridge [3], [4] another output separately is connected with the grid of [6] with field-effect transistor [5] respectively, field-effect transistor [5], [6] input with filter [9] after drain electrode is joined joins, the output of filter obtains the intermediate frequency output signal, field effect transistor [5], [6] source ground.