US 4,598,256 A · Tuned phase stable limiter amplifier

Abstract

A limiter amplifier having a pair of transistors connected in a common emitter, balanced push-pull amplifier type of circuit arrangement is disclosed. The transistors are interconnected by a series tuning capacitor at their emitters. A separate constant current source is connected to each of the emitters of the transistor pair. By selecting the value of the tuning capacitor to resonate with the inherent inductive component of the emitter source impedances in a particular frequency band, the limiter amplifier acts as a differential amplifier in the particular frequency band. The ac coupling of the emitters gives the limiter amplifier a bandpass filter type feature as well as high gain and low phase variation over large dynamic ranges of input signal amplitude. Impedance matching/buffer circuitry and isolation circuitry are also disclosed which permit the cascading of limiter amplifier gain stages. In a preferred embodiment of the invention, the limiter amplifier is formed in a monolithic integrated circuit and the tuning capacitor is mounted separately.

Claims27

Dependent claims

A tuned limiter amplifier comprising:

first and second circuit branches each having a bipolar transistor having an emitter source impedance with an inductive component thereof and a constant current circuit connected with the emitter of the transistor in a series circuit relationship;
a capacitor connected to the first circuit branch between the emitter and the constant current circuit and connected to the second circuit branch between the emitter and the constant current circuit;
and
the capacitor having a capacitance value selected so that it resonates with the inductive components of the emitter source impedances of both transistors in a selected frequency band thereby forming a bandpass filter;
whereby a balanced push-pull circuit is formed which is tuned by the capacitor.

2 more elements

A tuned limiter amplifier comprising:

first and second bipolar transistors, each having a base, a collector, and an emitter, and each having an emitter source impedance with an inductive component thereof;
first collector means for connecting the collector of the first transistor to a first potential;
second collector means for connecting the collector of the second transistor to a second potential;
first input means for applying an input signal to the base of the first transistor;
first and second output means for extracting output signals from the collectors of the first and second transistors respectively;
first and second current means for applying constant dc bias to the emitters of the first and second transistors respectively;
and
emitter coupling means for capacitively coupling the emitter of the first transistor to the emitter of the second transistor wherein the capacitance of the emitter coupling means is selected to resonate with the inductive components of the emitter source impedances of the first and second transistors in a selected frequency band thereby forming a bandpass filter;
whereby a balanced push-pull circuit is formed which is tuned by the emitter coupling means.

6 more elements

A tuned limiter amplifier comprising:

first and second transistors, each having a base, a collector, and an emitter, and each having an emitter source impedance with an inductive component thereof;
first collector means for connecting the collector of the first transistor to a first potential including a first resistor connected between the collector and the first potential;
second collector means for connecting the collector of the second transistor to a second potential including a second resistor connected between the collector and the second potential;
first and second input means for applying input signals to the bases of the first and second transistors respectively;
first and second output means for extracting output signals from the collectors of the first and second transistors respectively;
first and second current means for applying constant dc bias to the emitters of the first and second transistors respectively;
a monolithic semiconductor substrate into which is formed the first and second transistors and the first and second current means;
and
a capacitor connected in series between the emitters of the first and second transistors and having a capacitance value selected so that the capacitor resonates with the inductive components of the emitter source impedances of the first and second transistors in a selected frequency band thereby forming a bandpass filter, the capacitor being disposed at a position removed from the first and second transistor;
whereby a balanced push-pull circuit is formed which is tuned by the capacitor.

7 more elements

Dependencies are inferred from the claim text.

Tuned phase stable limiter amplifier

Life of this patent

Tuned phase stable limiter amplifier

Life of this patent

Abstract

Claims27