Balanced mixer using complementary devices
First Claim
Patent Images
1. A frequency changing circuit including in combination:
- first power supply conductor means for providing a power supply potential of one polarity;
second power supply conductor means for providing a power supply potential of the other polarity;
unbalanced input circuit means having first and second terminals, said unbalanced input circuit means providing a local oscillator signal and an input signal at first and second terminals thereof;
first electron control means of a first conductivity type coupled between said first power supply conductor means and said first terminal of said unbalanced input circuit means, said first electron control means having an output electrode and said first electron control means providing an output signal at said output electrode thereof;
second electron control means of a second conductivity type coupled between said second terminal of said unbalanced input circuit means and said second power supply conductor means, said second electron control means having an output electrode, and said second electron control means providing an output signal at said output electrode thereof; and
tuned circuit means coupled between said output electrodes of said first and second electron control means for selecting a balanced intermediate frequency signal in response to said output signals of said first and second electron control means, said first and second electron control means providing said local oscillator signal and said input signal in phase across said tuned circuit means so that substantially no local oscillator and no input signal components are produced in said tuned circuit means.
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Abstract
Frequency changing circuits are disclosed which each include an unbalanced input circuit, complementary mixing devices and a balanced output circuit. The mixer input signals are cancelled in the balanced output circuit. Moreover, whatever mixer out-of-phase output signals that are undesirably fed back to the input circuit are cancelled in the unbalanced input circuit. Also, circuitry is disclosed for rendering one or the other of the complementary mixing transistors inoperative so that the other of the complementary transistors can operate as a neutralized amplifier for utilization in a television receiver adapted to receive both VHF and UHF signals.
123 Citations
14 Claims
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1. A frequency changing circuit including in combination:
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first power supply conductor means for providing a power supply potential of one polarity; second power supply conductor means for providing a power supply potential of the other polarity; unbalanced input circuit means having first and second terminals, said unbalanced input circuit means providing a local oscillator signal and an input signal at first and second terminals thereof; first electron control means of a first conductivity type coupled between said first power supply conductor means and said first terminal of said unbalanced input circuit means, said first electron control means having an output electrode and said first electron control means providing an output signal at said output electrode thereof; second electron control means of a second conductivity type coupled between said second terminal of said unbalanced input circuit means and said second power supply conductor means, said second electron control means having an output electrode, and said second electron control means providing an output signal at said output electrode thereof; and tuned circuit means coupled between said output electrodes of said first and second electron control means for selecting a balanced intermediate frequency signal in response to said output signals of said first and second electron control means, said first and second electron control means providing said local oscillator signal and said input signal in phase across said tuned circuit means so that substantially no local oscillator and no input signal components are produced in said tuned circuit means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A frequency changing circuit suitable for combining the frequencies of a local oscillator signal and an input signal to provide an output signal having a predetemined frequency, including in combination:
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first power supply conductor means adapted to provide a power supply potential of the first polarity; second power supply conductor means adapted to provide a power supply potential of a second polarity; unbalanced input circuit means adapted to provide said local oscillator signal and said input signal at first and second terminals thereof; first electron control means having a control electrode connected to said first terminal, a first electrode coupled to said first power supply conductor means, and an output electrode, said first electron control means being rendered more conductive in response to alternate half cycles of said local oscillator signal of one polarity; second electron control means having a control electrode connected to said second terminal, a first electrode coupled to said power supply conductor means, and an output electrode, said second electron control means being rendered more conductive in response to alternate half cycles of said local oscillator signal of the other polarity; balanced tuned circuit means connected between said output electrodes of said first and second electron control means and which is arranged to select and provide signals of the predetermined frequency which are 180°
out-of-phase with respect to each other; andfirst capacitive means coupled between said control and output electrodes of said first and second electron control means, second capacitive means coupled between said control and output electrodes of said second electron control means, said first and second capacitive means coupling said 180°
out-of-phase signals of the predetermined frequency to said unbalanced input circuitry wherein said signal of the predetermined frequency are substantially cancelled. - View Dependent Claims (14)
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Specification