Gilbert cell phase modulator having two outputs combined in a balun

• US 5,844,449 A
• Filed: 09/08/1997
• Issued: 12/01/1998
• Est. Priority Date: 03/05/1997
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Ikuta, Hideki, Abeno, Ichiro
• Primary Examiner(s): Grimm, Siegfried H.
• Application Number:
  US08/925,410
• Time in Patent Office: 449 Days
• Field of Search: 332/103, 332/105, 332/144, 332/146, 375/302, 375/308, 455/110, 455/111
• US Class Current: 332/105
• CPC Class Codes: H03C 3/40 using two signal paths the outputs of which have a predetermined phase difference and at least one output being amplitude-modulated
• CPC Class Codes: H03D 2200/0023 Balun circuits
• CPC Class Codes: H03D 2200/0043 Bias and operating point
• CPC Class Codes: H03D 2200/0047 Offset of DC voltage or frequency
• CPC Class Codes: H03D 2200/0084 Lowering the supply voltage and saving power
• CPC Class Codes: H03D 7/1433 using bipolar transistors H03D7/145 takes precedence
• CPC Class Codes: H03D 7/1441 using field-effect transistors H03D7/145 takes precedence
• CPC Class Codes: H03D 7/165 at least two frequency changers being located in different paths, e.g. in two paths with carriers in quadrature combined with amplitude demodulation H03D1/2245, combined with angle demodulation H03D3/007; N-path filters H03H19/002
• CPC Class Codes: H04L 27/2039 using microwave technology
• CPC Class Codes: H04L 27/2064 using microwave technology

Abstract

A phase modulator having a Gilbert cell mixer can be used in frequency ranges from a microwave frequency band of several GHz to a millimeter wave band of several 10 GHz. Two output signals Vout1, Vout2 from the Gilbert cell mixer are supplied to balanced input terminals of a balanced-to-unbalanced converter, which produces a phase-modulated output signal Vout from an unbalanced output terminal thereof. Even when a differential amplifier comprising FETs Q1, Q3 and a differential amplifier comprising FETs Q2, Q4 do not operate symmetrically, the phase modulator generates phase-modulated output signals that have the same amplitude as each other and are in opposite phase to each other. With the Gilbert cell mixer comprising FETs, the phase modulator can be used in the frequency ranges described above. If the balanced-to-unbalanced converter is in the form of a planar circuit, then the phase modulator may be implemented by an MMIC.

Claims

1. A phase modulator for use in at least a microwave frequency band and a millimeter wave band, comprising:

first and second FETs having respective gates for being supplied with a carrier signal;

a third FET having a gate AC-coupled to ground, a drain connected to a drain of said second FET, and a source connected to a source of said first FET;

a fourth FET having a gate AC-coupled to ground, a drain connected to a drain of said first FET, and a source connected to a source of said second FET;

a fifth FET having a gate for being supplied with a baseband signal, a drain connected to the sources of said first and third FETs, and a source connected to ground;

a sixth FET having a gate for being supplied with a reversal of said baseband signal, a drain connected to the sources of said second and fourth FETs, and a source connected to ground; and

a balanced-to-unbalanced converter for shifting, by π

/2, the phase of one of an output signal produced from the drain of said first FET and an output signal produced from the drain of said second FET, combining the phase-shifted signal with the other output signal, and producing a combined output signal.

2. A phase modulator according to claim 1, wherein said balanced-to-unbalanced converter comprises a planar circuit, and said planar circuit and said first, second, third, fourth, fifth, and sixth FETs are implemented by a monolithic microwave integrated circuit.

3. A phase modulator according to claim 1, further comprising a constant-current power supply connected between the sources of said fifth and sixth FETs and ground.

4. A phase modulator for use in at least a microwave frequency band and a millimeter wave band, comprising:

first and second FETs having respective gates for being supplied with a carrier signal;

a third FET having a gate for being supplied with a baseband signal, a drain connected to a source of said first FET, and a source connected to ground;

a fourth FET having a gate for being supplied with a reversal of said baseband signal, a drain connected to the source of said second FET, and a source connected to ground; and

a balanced-to-unbalanced converter for shifting, by π

/2, the phase of one of an output signal produced from the drain of said first FET and an output signal produced from the drain of said second FET, combining the phase-shifted signal with the other output signal, and producing a combined output signal.

5. A phase modulator according to claim 4, wherein said balanced-to-unbalanced converter comprises a planar circuit, and said planar circuit and said first, second, third, and fourth FETs are implemented by a monolithic microwave integrated circuit.

6. A phase modulator according to claim 4, further comprising a constant-current power supply connected between the sources of said third and fourth FETs and ground.

7. A phase modulator for use in at least a microwave frequency band and a millimeter wave band, comprising:

a first dual-gate FET having a first gate for being supplied with a carrier signal, a second gate for being supplied with a baseband signal, and a source connected to ground;

a second dual-gate FET having a first gate for being supplied with said carrier signal, a second gate for being supplied with a reversal of said baseband signal, and a source connected to ground; and

a balanced-to-unbalanced converter for shifting, by π

/2, the phase of one of an output signal produced from the drain of said first dual-gate FET and an output signal produced from the drain of said second dual-gate FET, combining the phase-shifted signal with the other output signal, and producing a combined output signal.

8. A phase modulator according to claim 7, wherein said balanced-to-unbalanced converter comprises a planar circuit, and said planar circuit and said first and second dual-gate FETs are implemented by a monolithic microwave integrated circuit.

9. A phase modulator according to claim 7, further comprising a constant-current power supply connected between the sources of said first and second dual-gate FETs and ground.

10. A phase modulator comprising:

first and second bipolar transistors having respective bases for being supplied with a carrier signal;

a third bipolar transistor having a base AC-coupled to ground, a collector connected to a collector of said second bipolar transistor, and an emitter connected to an emitter of said first bipolar transistor;

a fourth bipolar transistor having a base AC-coupled to ground, a collector connected to a collector of said first bipolar transistor, and an emitter connected to an emitter of said second bipolar transistor;

a fifth bipolar transistor having a base for being supplied with a baseband signal, a collector connected to the emitters of said first and third bipolar transistors, and an emitter connected to ground;

a sixth bipolar transistor having a base for being supplied with a reversal of said baseband signal, a collector connected to the emitters of said second and fourth bipolar transistors, and an emitter connected to ground; and

a balanced-to-unbalanced converter for shifting, by π

/2, the phase of one of an output signal produced from the collector of said first bipolar transistor and an output signal produced from the collector of said second bipolar transistor, combining the phase-shifted signal with the other output signal, and producing a combined output signal.

11. A phase modulator comprising:

first and second bipolar transistors having respective bases for being supplied with a carrier signal;

a third bipolar transistor having a base for being supplied with a baseband signal, a collector connected to an emitter of said first bipolar transistor, and an emitter connected to ground;

a fourth bipolar transistor having a base for being supplied with a reversal of said baseband signal, a collector connected to an emitter of said second bipolar transistor, and an emitter connected to ground; and

a balanced-to-unbalanced converter for shifting, by π

/2, the phase of one of an output signal produced from a collector of said first bipolar transistor and an output signal produced from a collector of said second bipolar transistor, combining the phase-shifted signal with the other output signal, and producing a combined output signal.

12. A quadrature phase modulator for use in at least a microwave frequency band and a millimeter wave band, comprising:

a distributor for dividing a carrier signal into two carrier signals in phase with each other;

first and second FETs having respective gates for being supplied with one of said carrier signals from said distributor;

a third FET having a gate AC-coupled to ground, a drain connected to a drain of said second FET, and a source connected to a source of said first FET;

a fourth FET having a gate AC-coupled to ground, a drain connected to a drain of said first FET, and a source connected to a source of said second FET;

a fifth FET having a gate for being supplied with a first baseband signal, a drain connected to the sources of said first and third FETs, and a source connected to ground;

a sixth FET having a gate for being supplied with a reversal of said first baseband signal, a drain connected to the sources of said second and fourth FETs, and a source connected to ground;

a first balanced-to-unbalanced converter for shifting, by π

/2, the phase of one of an output signal produced from the drain of said first FET and an output signal produced from the drain of said second FET, combining the phase-shifted signal with the other output signal, and producing a combined output signal;

a phase shifter for shifting, by π

/2, the phase of the other carrier signal from said distributor;

seventh and eighth FETs having respective gates for being supplied with the carrier signal shifted in phase by said phase shifter;

a ninth FET having a gate AC-coupled to ground, a drain connected to a drain of said eighth FET, and a source connected to a source of said seventh FET;

a tenth FET having a gate AC-coupled to ground, a drain connected to a drain of said seventh FET, and a source connected to a source of said eighth FET;

an eleventh FET having a gate for being supplied with a second baseband signal, a drain connected to the sources of said seventh and ninth FETs, and a source connected to ground;

a twelfth FET having a gate for being supplied with a reversal of said second baseband signal, a drain connected to the sources of said eighth and tenth FETs, and a source connected to ground;

a second balanced-to-unbalanced converter for shifting, by π

/2, the phase of one of an output signal produced from the drain of said seventh FET and an output signal produced from the drain of said eighth FET, combining the phase-shifted signal with the other output signal, and producing a combined output signal; and

a combiner for combining the output signal from said first balanced-to-unbalanced converter and the output signal from said second balanced-to-unbalanced converter into a quadrature phase-modulated output signal.

13. A quadrature phase modulator for use in at least a microwave frequency band and a millimeter wave band, comprising:

a distributor for dividing a carrier signal into two carrier signals in phase with each other;

first and second FETs having respective gates for being supplied with one of said carrier signals from said distributor;

a third FET having a gate for being supplied with a first baseband signal, a drain connected to a source of said first FET, and a source connected to ground;

a fourth FET having a gate for being supplied with a reversal of said first baseband signal, a drain connected to a source of said second FET, and a source connected to ground;

a first balanced-to-unbalanced converter for shifting, by π

/2, the phase of one of an output signal produced from a drain of said first FET and an output signal produced from a drain of said second FET, combining the phase-shifted signal with the other output signal, and producing a combined output signal;

a phase shifter for shifting, by π

/2, the phase of the other carrier signal from said distributor;

fifth and sixth FETs having respective gates for being supplied with the carrier signal shifted in phase by said phase shifter;

a seventh FET having a gate for being supplied with a second baseband signal, a drain connected to a source of said fifth FET, and a source connected to ground;

an eighth FET having a gate for being supplied with a reversal of said second baseband signal, a drain connected to a source of said sixth FET, and a source connected to ground;

a second balanced-to-unbalanced converter for shifting, by π

/2, the phase of one of an output signal produced from a drain of said fifth FET and an output signal produced from a drain of said sixth FET, combining the phase-shifted signal with the other output signal, and producing a combined output signal; and

a combiner for combining the output signal from said first balanced-to-unbalanced converter and the output signal from said second balanced-to-unbalanced converter into a quadrature phase-modulated output signal.

14. A quadrature phase modulator for use in at least a microwave frequency band and a millimeter wave band, comprising:

a distributor for dividing a carrier signal into two carrier signals in phase with each other;

a first dual-gate FET having a first gate for being supplied with one of said carrier signals from said distributor, a second gate for being supplied with a first baseband signal, and a source connected to ground;

a second dual-gate FET having a first gate for being supplied with said one of said carrier signals, a second gate for being supplied with a reversal of said first baseband signal, and a source connected to ground;

a first balanced-to-unbalanced converter for shifting, by π

/2, the phase of one of an output signal produced from a drain of said first dual-gate FET and an output signal produced from a drain of said second dual-gate FET, combining the phase-shifted signal with the other output signal, and producing a combined output signal;

a phase shifter for shifting, by π

/2, the phase of the other carrier signal from said distributor;

a third dual-gate FET having a first gate for being supplied with the carrier signal shifted in phase by said phase shifter, a second gate for being supplied with a second baseband signal, and a source connected to ground;

a fourth dual-gate FET having a first gate for being supplied with the carrier signal shifted in phase by said phase shifter, a second gate for being supplied with a reversal of said second baseband signal, and a source connected to ground;

a second balanced-to-unbalanced converter for shifting, by π

/2, the phase of one of an output signal produced from a drain of said third dual-gate FET and an output signal produced from a drain of said fourth dual-gate FET, combining the phase-shifted signal with the other output signal, and producing a combined output signal; and

a combiner for combining the output signal from said first balanced-to-unbalanced converter and the output signal from said second balanced-to-unbalanced converter into a quadrature phase-modulated output signal.