High frequency four quadrant multiplier

Claim 2

A four quadrant multiplier circuit for obtaining the bi-polar product of a pair of signed signal voltages, comprising, a double side band suppressed carrier modulator, means for supplying (1) a fixed frequency voltage and (2) one of said signed signal voltages to said modulator, means for translating the second of said signed signal voltages to a voltage having a phase locked in synchronism to the phase of said fixed frequency voltage, a phase detector of the ring modulator type, means for applying (1) the output of said modulator and (2) the output of said means for translating to said phase detector, and means for obtaining an output signal from said phase detector which is proportional to the bi-polar product of said signed signal voltages.

Claim 3

A multiplier circuit for obtaining the bi-polar product of a pair of high frequency signal voltages, comprising, means for supplying a fixed frequency voltage which iS higher in frequency than the frequency of said pair of signal voltages, an amplitude modulator, means for applying one of said signal voltages and said fixed frequency voltage to said amplitude modulator to produce a sideband voltage having an amplitude proportional to said one signal voltage and in phase with said one fixed frequency voltage when said one signal voltage is of one polarity and 180* out of phase with said fixed frequency voltage when said one signal voltage is of opposite polarity, a phase linearizing loop including a phase detector, a voltage controlled oscillator having a nominal center frequency the same as said fixed frequency voltage, and a differential amplifier, means for applying said fixed frequency voltage as one input to said phase detector and the signal from of said voltage controlled oscillator as the second input thereto, means for applying the output of said phase detector as one input to said differential amplifier and the second of said two high frequency signals voltages as the second input to said differential amplifier, means applying the output of said amplifier to said voltage controlled oscillator to control same, a second phase detector, means for applying the outputs of said amplitude modulator and said voltage controlled oscillator to said second phase detector and means for obtaining an output signal from said second phase detector proportional to the bi-polar product of said two high frequency signals.

Claim 4

A multiplier circuit for obtaining the bi-polar product of a pair of high frequency signal voltages, comprising, means for supplying a fixed frequency voltage which iS higher in frequency than the frequency of said pair of signal voltages, an amplitude modulator, means for applying one of said signal voltages and said fixed frequency voltage to said amplitude modulator to produce a sideband voltage having an amplitude proportional to said one signal voltage and in phase with said one fixed frequency voltage when said one signal voltage is of one polarity and 180* out of phase with said fixed frequency voltage when said one signal voltage is of opposite polarity, a phase linearizing loop including a phase detector, a voltage controlled oscillator having a nominal center frequency the same as said fixed frequency voltage, and a differential amplifier, means for applying said fixed frequency voltage as one input to said phase detector and the signal from of said voltage controlled oscillator as the second input thereto, means for applying the output of said phase detector as one input to said differential amplifier and the second of said two high frequency signals voltages as the second input to said differential amplifier, means applying the output of said amplifier to said voltage controlled oscillator to control same, a second phase detector, means for applying the outputs of said amplitude modulator and said voltage controlled oscillator to said second phase detector and means for obtaining an output signal from said second phase detector proportional to the bi-polar product of said two high frequency signals.

Claim 5

The invention defined in claim 2 wherein said phase detectors are identical and constituted by double balanced mixer circuits.

Claim 6

The invention defined in claim 2 wherein said amplitude modulator and said phase detectors are substantially identical and are constituted by double balanced mixer circuits.

Claim 7

The invention defined in claim 4 wherein each said double balanced mixer circuits is of the ring modulator type.

Claim 8

The invention defined in claim 2 including filter means connected between the first said phase detector and said differential amplifier for removing any component of said fixed frequency voltage from the voltage applied to said differential amplifier.

Claim 9

The invention defined in claim 2 wherein said differential amplifier has a frequency response characteristic which is at least as high as the frequency of the high frequency signal voltage applied thereto.