Clipper circuitry

A combination comprising:

• first and second signal input terminals for receiving a changing input signal voltage therebetween;
• first and second power terminals for the application therebetween of an operating potential;
• first, second, third, and fourth bipolar transistors of a first conductivity type, each transistor having a base, an emitter, and a collector;
• means connecting the base of said first transistor to said first signal input terminal;
• means connecting the base of said third transistor to the collector of said second transistor;
• means connecting the emitter of said third transistor and the base of said second transistor to a first node;
• resistive means for providing a resistance between said first node and said second signal input terminal;
• current supply means connected between said second power terminal and the collectors of said first and said second transistors;
• means connecting the emitters of said first and said second transistors in common to a second node;
• means connecting the collector to emitter path of said fourth transistor between said second node and said first power terminal;
• means for selectively applying forward bias to the base electrode of said fourth transistor to condition its otherwise non-conductive collector to emitter path for conduction, responsive to which conduction the otherwise non-conductive said third transistor is conditioned to conduct collector current solely in response to said input signal voltage being of a particular polarity, as tends to cut off conduction of the fourth transistor collector current through the collector to emitter path of said second transistor and thus increase conduction of the fourth transistor collector current through the collector to emitter path of said first transistor, to thereby forward bias the base of said third transistor conditioning said third transistor to conduct collector current;
• and
• means for utilizing, as an output signal, the collector current of said third transistor flowing in response to those portions of said input signal voltage that are of said particular polarity.

A combination comprising:

• first and second signal input terminals;
• first and second power terminals for the application therebetween of an operating potential;
• first, second, and third transistors, each transistor having first and second electrodes defining the ends of a conduction path and a control electrode;
• means connecting the first electrodes of the first and second transistors in common to a first node;
• means connecting a selectively enabled current source between said first node and said first power terminal for causing said first and second transistors to function as a differential amplifying stage only when said current source is enabled;
• means connecting the control electrode of said third transistor to the second electrode of said second transistor;
• means connecting the control electrode of said first transistor to said first signal input terminal;
• means connecting the first electrode of said third transistor and the control electrode of said second transistor to a second node;
• means for providing a resistive path for current between said second node and said second signal input terminal, which resistive path exhibits a resistance of value R between said second node and said second signal input terminal;
• current supply means connected between said second power terminal and the second electrodes of said first and second transistors;
• means for applying an alternating current (AC) signal between said first and second signal input terminals and for, in response thereto, producing a unidirectional output current via the conduction path of said third transistor, the amplitude of which unidirectional output current is a function of the amplitude of the AC signal divided by R;
• and
• further circuitry having an input circuit connected between first electrode of said third transistor and said second power terminal to which said unidirectional output current is supplied for utilization.

A combination comprising:

• an input signal terminal for the application thereto of an input signal, portions of which that are more negative than a first reference potential or that are more positive than a second reference potential are to be detected on an absolute-value basis during gating intervals;
• first clipping means connected to receive a respective input signal from said input signal terminal, said first clipping means having an output terminal for supplying a respective output signal linearly responsive to the portions of said input signal that are more negative than said first reference potential;
• second clipping means connected to receive a respective input signal from said input signal terminal, said second clipping means having an output terminal for supplying a respective output signal linearly responsive to portions of said input signal that are more positive than said second reference potential;
• and
• means for summing the output signals of said first and second clipping means for producing a combined output signal detecting on an absolute-value basis portions of said input signal that swing beyond a first reference potential in a direction away from a second reference potential or that swing beyond said second reference potential in a direction away from said first reference potential;
• wherein said first clipping means includes:
• a) a first resistive element having a first end connected to said input signal terminal, having a second end, and exhibiting a first ohmic value between its first and second ends;
• b) a first differential-input amplifier having a non-inverting input node to which said first reference potential is applied, having an inverting input node connected to the second end of said first resistive element, and having an output node;
• and
• c) first current feedback amplifying means having an input connection from the output of said first differential-input amplifier, having a common connection to the inverting input node of said first differential-input amplifier, and having an output connection to the output terminal of said first clipping means--and wherein said second clipping means includes:
• d) a second resistive element having a first end connected to said input signal terminal, having a second end, and exhibiting a second ohmic value between its first and second ends;
• e) a second differential-input amplifier having an inverting input node to which said second reference potential is applied, having a non-inverting input node connected to the second end of said second resistive element, and having an output node;
• and
• f) second current feedback amplifying means having an input connection from the output node of said second differential-input amplifier, having a common connection to the inverting input node of said second differential-input amplifier, and having an output connection to the output terminal of said second clipping means.

A combination comprising:

• an input signal terminal for the application thereto of an input signal, portions of which are to be detected on an absolute-value basis;
• first clipping means connected to receive a respective input signal from said input signal terminal, said first clipping means having an output terminal for supplying a respective output signal linearly responsive to the portions of said input signal that are more negative than a first reference potential;
• second clipping means connected to receive a respective input signal from said input signal terminal, said second clipping means having an output terminal for supplying a respective output signal linearly responsive to the portions of said input signal that are more positive than a second reference potential;
• and
• means for summing the output signals of said first and second clipping means for producing a combined output signal detecting on an absolute-value basis portions of said input signal that swing beyond a first reference potential in a direction away from a second reference potential or that swing beyond said second reference potential in a direction away from said first reference potential, wherein said first clipping means includes:
• a) a first resistive element having a first end connected to said input signal terminal, having a second end, and exhibiting a first ohmic value between its first and second ends;
• b) a first differential-input amplifier having a non-inverting input node to which said first reference potential is applied, having an inverting input node connected to the second end of said first resistive element, and having an output node;
• and
• c) first current feedback amplifying means having an input connection from the output node of said first differential-input amplifier, having a common connection to the inverting input node of said first differential-input amplifier, and having an output connection to
• the output terminal of said first clipping means and wherein said second clipping means includes:
• d) a second resistive element having a first end connected to said input signal terminal, having a second end, and exhibiting a second ohmic value between its first and second ends;
• e) a second differential-input amplifier having an inverting input node to which said second reference potential is applied, having a non-inverting input node connected to the second end of said second resistive element, and having an output node;
• and
• f) second current feedback amplifying means having an input connection from the output node of said second differential-input amplifier, having a common connection to the inverting input node of said second differential-input amplifier, and having an output connection to the output terminal of said second clipping means.

A full-wave rectifier comprising, in addition to first and second input signal terminals and an output signal terminal, the following elements:

• (a) a first differential-input amplifier having a respective non-inverting input node connected to said first input signal terminal, having a respective inverting input node, and having a respective output node;
• (b) a first feedback amplifier having a respective input connection from the output node of said first differential-input amplifier, having a respective output connection, and having a common connection to the inverting input node of said first differential-input amplifier for providing degenerative feedback thereto, responsive to which a first current flows through the output connection of said first feedback amplifier;
• (c) a first resistive element having an ohmic value connecting between said inverting input node of said first differential-input amplifier and said second input signal terminal, said elements (a) and (b) and (c) cooperating to provide a first half-wave rectifier stage;
• d) a second differential-input amplifier having a respective non-inverting input node connected to said second input signal terminal, having a respective inverting input node, and having a respective output node;
• e) a second feedback amplifier having a respective input connection from the output node of said second differential-input amplifier, having a respective output connection, and having a common connection to the inverting input node of said second differential-input amplifier for providing degenerative feedback thereto, responsive to which a second current flows through the output connection of said second feedback amplifier;
• f) a second resistive element having an ohmic value connecting between said inverting input node of said second differential-input amplifier and said first input signal terminal, said elements (d) and (e) and (f) cooperating to provide a second half-wave rectifier stage;
• and
• (g) summing means connecting the common connections of said first and second feedback amplifiers together at said output signal terminal for said full-wave rectifier.

A combination comprising:

• an input terminal and an output terminal;
• a differential-input amplifier having a non-inverting input node, an inverting input node, and an output node;
• a resistive element having an ohmic value between said inverting input node and said input terminal;
• means for applying a reference voltage to said non-inverting input node;
• means for applying an alternating current (AC) signal to said input terminal, said AC signal swinging away from said reference voltage in a first direction at times and swinging away from said reference voltage in a second direction at other times, said first and second directions being of opposite senses of polarity;
• a feedback amplifier having an input connection to said output node, a first output connection to said inverting input node for completing a degenerative feedback loop and for supplying current to said inverting input node tending to maintain the potential at said inverting input node equal to the potential at said non-inverting input node only when said AC signal does not swing appreciably away from said reference voltage in said first direction, and a second output connection to said output terminal through which a clipped signal current flows only responsive to said feedback amplifier supplying said current to said inverting input node;
• and
• further circuitry having an input circuit connected from said output terminal, for utilizing said clipped signal current.