Microwave phase locked loops using fet frequency dividers

Claim 2

A microwave frequency generator comprising a micro-wave frequency rf oscillator having a control input and having an output forming the output of the microwave frequency generator, a microwave frequency divider having an input connected to receive the output of the rf oscillator and frequency divide it by a factor N and having an output connected to one input of a phase detector, said phase detector having another input connected to receive the output of a reference oscillator and having an output connected to said control input, whereby the rf oscillator produces an rf frequency of N times the frequency of the reference oscillator, said microwave frequency divider comprising at least one MESFET (metal semi-conductor field effect transistor) having a gate, a source and a drain, a first transmission line connected to said gate and source and to input terminal means, said transmission line forming, with inherent frequency dependent non-linear capaci-tance between said gate and source, a resonant circuit at fo/N, where fO is the frequency to be applied to said input terminal means, a second transmission line being connected to said source and drain and to output terminal means, whereby said MESFET simultaneously provides parametric frequency division and amplification at microwave frequencies.

Claim 3

A microwave frequency generator as claimed in claim 1 wherein N is 2.

Claim 4

A microwave frequency generator comprising a microwave frequency rf oscillator having a control input and having an output forming the output of the microwave frequency generator, a microwave frequency divider having an input connected to receive the output of the rf oscillator and frequency divide it by a factor N and having an output connected to one input of a phase detector, said phase detector having another input connected to receive the output of a reference oscillator and having an output connected to said control input, whereby the rf oscillator produces an rf frequency of N times the frequency of the reference oscillator, said microwave frequency divider comprising a first and a second MESFET (metal semi-conductor field effect transistor), each having a source electrode, a drain electrode and a gate electrode, the gate of said first MESFET being connected via a first transmission line to an input terminal and the gate of said second MESFET being connected via a second transmission line to said input terminal, said source electrodes being connected to ground, said drain electrodes being connected via third and fourth transmission lines to a balun transformer having output con-nection means, said first and second transmission lines being of equal length and forming, with inherent gate-to-source frequency dependent non-linear capacitances of the MESFET's, a circuit resonant at fo/N where fo is the frequency of the rf oscillator, said MESFET's simultaneously providing para-metric frequency division and amplification at microwave frequencies.

Claim 5

A microwave frequency generator comprising a microwave frequency rf oscillator having a control input and having an output forming the output of the microwave frequency generator, a microwave frequency divider having an input connected to receive the output of the rf oscillator and frequency divide it by a factor N and having an output connected to one input of a phase detector, said phase detector having another input connected to receive the output of a reference oscillator and having an output connected to said control input, whereby the rf oscillator produces an rf frequency of N times the frequency of the reference oscillator, said microwave frequency divider comprising a first and a second MESFET (metal semi-conductor field effect transistor), each having a source electrode, a drain electrode and a gate electrode, the gate of said first MESFET being connected via a first transmission line to an input terminal and the gate of said second MESFET being connected via a second transmission line to said input terminal, said source electrodes being connected to ground, said drain electrodes being connected via third and fourth transmission lines to a balun transformer having output con-nection means, said first and second transmission lines being of equal length and forming, with inherent gate-to-source frequency dependent non-linear capacitances of the MESFET's, a circuit resonant at fo/N where fo is the frequency of the rf oscillator, said MESFET's simultaneously providing para-metric frequency division and amplification at microwave frequencies.

Claim 6

A microwave frequency generator as claimed in claim 3 wherein N is 2.

Claim 7

A microwave frequency generator as claimed in claim 4 wherein said transmission lines are microstrip lines.

Claim 8

A microwave frequency generator as claimed in claim 5 wherein a DC blocking capacitor is connected between said input terminal and said first and second transmission lines.

Claim 9

A microwave frequency generator as claimed in claim 6 wherein said third and fourth transmission lines provide impedance matching at fo/2.

Claim 10

A microwave frequency generator as claimed in claim 7 wherein said third and fourth transmission lines are connected to said balun transformer via DC blocking capacitors.

Claim 11

A microwave frequency generator as claimed in claim 8 wherein high impedance means are provided for applying bias voltage to said drains.

Claim 12

A microwave frequency generator as claimed in claim 9 wherein high impedance means are provided for applying bias voltage to said gates.