US 5,220,686 A · Tunable resonance amplifier

Abstract

An amplifier with a non-regenerative DC negative feedback loop which incorporates first and second first-order low-pass RC filters, has a signal path arranged from an input to an output and a feedback path arranged from the output to the input, and has a controlled loop gain. To provide substantially even selective amplification over a comparatively large tuning control range, the signal path incorporates one of the two RC filters and the feedback path incorporates the other RC filter together with the controlled loop gain; or the signal path incorporates the two RC filters together with one part of the controlled loop gain and the feedback path incorporates the other part of the controlled loop gain. To reduce the required power supply voltage and hence decrease the power dissipation of a frequency synthesis circuit, a tunable resonance amplifier is arranged between the voltage-controlled oscillator and the frequency divider circuit, and the loop filter is coupled to a tuning control input of the tunable resonance amplifier for simultaneously tuning the voltage-controlled oscillator and the tunable resonance amplifier.

Claims24

Dependent claims

A tunable resonance amplifier comprising a non-regenerative DC negative feedback loop which includes means for controllably amplifying signals at signal frequencies to provide a controlled loop gain, said loop having a signal path for said signals from an input to an output thereof and a feedback path for said signals from said output to said input;

characterized in that:
said amplifying means comprises a pair of amplifiers having controllable gain factors, at least one of said amplifiers being in said feedback path;
said loop further includes a pair of first-order low-pass RC filters, at least one of said filters being in said signal path;
and
said amplifiers and said filters are arranged in cascade around said loop in a sequence such that the respective amplifiers alternate with the respective filters;
the pair of amplifiers being substantially identical and the pair of filters being substantially identical.

3 more elements

A superheterodyne receiver successively comprising an RF input section, a tunable mixer stage, an IF section and a demodulation device, characterized in that:

the IF section comprises a tunable resonance amplifier having a non-regenerative DC negative feedback loop including means for amplifying signals at signal frequencies to provide a controlled loop gain, said means for amplifying comprising first and second controlled amplifiers,
said loop has a signal path for said signals arranged from an input to an output;
and a feedback path for said signals arranged from said output to said input, and said loop includes a first and a second first-order low-pass RC filter, and means for signal inversion,
the signal path incorporates one of said RC filters, and said feedback path incorporates the other of said RC filters and said means for amplifying,
said first and second controlled amplifiers are first and second transconductance circuits each having a controllable transconductance from a voltage input to a current output, the current outputs of the first and second transconductance circuits being coupled via parallel RC members of the first and second RC filters to the voltage inputs of the second and first transconductance circuits, respectively;
and the input of the resonance amplifier being coupled to the input of at least one of the two transconductance circuits for applying an input signal current thereto and the output of the resonance amplifier being coupled to the output of one of the two transconductance circuits for applying an output signal voltage thereto, and
the outputs of the first and second transconductance circuits are connected to inputs and outputs of third and fourth transconductance circuits, respectively, said third and fourth transconductance circuits being controllable and being coupled via a control input to signal circuits.

4 more elements

A superheterodyne receiver successively comprising an RF input section, a tunable mixer stage, an IF section and a demodulation device, characterized in that:

the IF section comprises a tunable resonance amplifier having a non-regenerative DC negative feedback loop including means for amplifying signals at signal frequencies to provide a controlled loop gain, said means for amplifying comprising first and second controlled amplifiers,
said loop has a signal path for said signals arranged from an input to an output;
and a feedback path for said signals arranged from said output to said input, and said loop includes a first and a second first-order low-pass RC filter, and means for signal inversion,
said first controlled amplifier supplies one part only of said controlled loop gain, and said second controlled amplifier supplies the other part of said controlled loop gain;
and the signal path incorporates both said RC filters and said first controlled amplifier,
said first and second controlled amplifiers are first and second transconductance circuits each having a controllable transconductance from a voltage input to a current output, the current outputs of the first and second transconductance circuits being coupled via parallel RC members of the first and second RC filters to the voltage inputs of the second and first transconductance circuits, respectively;
and the input of the resonance amplifier being coupled to the input of at least one of the two transconductance circuits for applying an input signal current thereto and the output of the resonance amplifier being coupled to the output of one of the two transconductance circuits for applying an output signal voltage thereto, and
the outputs of the first and second transconductance circuits are connected to inputs and outputs of third and fourth transconductance circuits, respectively, said third and fourth transconductance circuits being controllable and being coupled via a control input to signal circuit.

5 more elements

Dependencies are inferred from the claim text.

Tunable resonance amplifier

Life of this patent

Tunable resonance amplifier

Life of this patent

Abstract

Claims24