Voltage adjustable capacitance for frequency response shaping

Claim 2

A substantially constant capacitance circuit for use with an external circuit having a variable voltage signal across first and second terminals, said capacitance circuit comprising: first voltage means for supplying voltage having a positive terminal operatively connected to the first terminal; second voltage means for supplying a voltage having a positive terminal operatively connected to the second terminal; first, second, third and fourth reverse biased means for providing a voltage dependent capacitance, said first biased means connected across said first voltage means and said fourth biased means connected across said second voltage means, said second biased means connected from one side of said first voltage means to the opposed side of said second voltage means and said third biased means connected between said first and second voltage means in an opposite configuration to said second biased means, said first, second, third and fourth biased means connected to be reversed biased by said variable voltage signal and by said first and second voltage means; wherein said substantially constant capacitance circuit provides a substantially constant equivalent capacitance across the first and second terminals of the external circuit as the level of the variable voltage signal changes.

Claim 3

The circuit described in claim 1 wherein said first and second voltage means are variable thereby providing adjustment of the equivalent capacitance provided to the first and second terminals.

Claim 4

A substantially constant capacitance circuit for use with an external circuit having a variable voltage signal across first and second terminals, said capacitance circuit comprising: a first variable voltage source having its positive terminal operatively connected to the first terminal; a second variable voltage source having its positive terminal operatively connected to the second terminal; first, second, third and fourth reverse biased diodes, said first diode connected across said first voltage source and said fourth diode connected across said second voltage source, said second diode connected from one side of said first voltage source to the opposed side of said second voltage source and said third diode connected between said first and second voltage sources in an opposite configuration to said second diode, said first, second, third and fourth diodes connected to be reversed biased by the variable voltage signal and by said first and second voltage sources; wherein said substantially constant capacitance circuit provides a substantially constant equivalent capacitance across the first and second terminals of the external circuit as the level of the variable voltage signal changes.

Claim 5

A substantially constant capacitance circuit for use with an external circuit having a variable voltage signal across first and second terminals, said capacitance circuit comprising: a first variable voltage source having its positive terminal operatively connected to the first terminal; a second variable voltage source having its positive terminal operatively connected to the second terminal; first, second, third and fourth reverse biased diodes, said first diode connected across said first voltage source and said fourth diode connected across said second voltage source, said second diode connected from one side of said first voltage source to the opposed side of said second voltage source and said third diode connected between said first and second voltage sources in an opposite configuration to said second diode, said first, second, third and fourth diodes connected to be reversed biased by the variable voltage signal and by said first and second voltage sources; wherein said substantially constant capacitance circuit provides a substantially constant equivalent capacitance across the first and second terminals of the external circuit as the level of the variable voltage signal changes.

Claim 6

A substantially constant capacitance for increasing the frequency of a transconductance amplifier having at least a circuit for producing an output current from an output voltage and having a predetermined gain, said circuit comprising: means for receiving an input voltage and for producing the output voltage in response to said input voltage; means for setting the gain of the transconductance amplifier and operatively connected to said means for receiving; and variable means for increasing the frequency response of the transconductance amplifier by providing a substantially constant capacitance across the means for setting the gain and operatively connected to said means for receiving and to said means for setting the gain and which is unaffected by changes in the level of said input voltage, said variable means for increasing the frequency response of the transconductance amplifier being voltage controlled comprising at least means for supplying a variable voltage.

Claim 7

A substantially constant capacitance for increasing the frequency of a transconductance amplifier having at least a circuit for producing an output current from an output voltage and having a predetermined gain, said circuit comprising: means for receiving an input voltage and for producing the output voltage in response to said input voltage; means for setting the gain of the transconductance amplifier and operatively connected to said means for receiving; and variable means for increasing the frequency response of the transconductance amplifier by providing a substantially constant capacitance across the means for setting the gain and operatively connected to said means for receiving and to said means for setting the gain and which is unaffected by changes in the level of said input voltage, said variable means for increasing the frequency response of the transconductance amplifier being voltage controlled comprising at least means for supplying a variable voltage.

Claim 8

A substantially constant capacitance for increasing the frequency of a transconductance amplifier having at least a circuit for producing an output current from an output voltage and having a predetermined gain, said circuit comprising: means for receiving an input voltage and for producing the output voltage in response to said input voltage; means for setting the gain of the transconductance amplifier and operatively connected to said means for receiving; and variable means for increasing the frequency response of the transconductance amplifier by providing a substantially constant capacitance across the means for setting the gain and operatively connected to said means for receiving and to said means for setting the gain and which is unaffected by changes in the level of said input voltage, said variable means for increasing the frequency response comprising at least four voltage controlled reverse biased diodes operatively connected in a series-parallel configuration.

Claim 9

A substantially constant capacitance for increasing the frequency of a transconductance amplifier having at least a circuit for producing an output current from an output voltage and having a predetermined gain, said circuit comprising: means for receiving an input voltage and for producing the output voltage in response to said input voltage; means for setting the gain of the transconductance amplifier and operatively connected to said means for receiving; and variable means for increasing the frequency response of the transconductance amplifier by providing a substantially constant capacitance across the means for setting the gain and operatively connected to said means for receiving and to said means for setting the gain and which is unaffected by changes in the level of said input voltage, said variable means for increasing the frequency response comprising at least four voltage controlled reverse biased diodes operatively connected in a series-parallel configuration.

Claim 10

A substantially constant capacitance for increasing the frequency of a transconductance amplifier having at least a circuit for producing an output current from an output voltage and having a predetermined gain, said circuit comprising: means for receiving an input voltage and for producing the output voltage in response to said input voltage, said means for receiving having a positive input terminal for receiving said input voltage and a negative input terminal for receiving a reference voltage, operatively connected, respectively, to first and second semiconductor means for accepting the input voltage and reference voltage received on said positive and negative input terminals; means for setting the gain of the transconductance amplifier and operatively connected to said means for receiving; and variable means for increasing the frequency response of the transconductance amplifier by providing a substantially constant capacitance across the means for setting the gain and operatively connected to said means for receiving and to said means for setting the gain and which is unaffected by changes in the level of said input voltage, said variable means for increasing the frequency response comprising a first variable voltage source operatively connected to said first semiconductor means and a second variable voltage source operatively connected to said second semiconductor means and first, second, third and fourth reverse biased diodes, said first diode connected across said first voltage source and said fourth diode connected across said second voltage source, said second diode connected from one side of said first voltage source to the opposed side of said second voltage source and said third diode connected between said first and second voltage sources in an opposite configuration to said second diode, said first, second, third and fourth diodes connected to be reversed biased by said input voltage, said reference voltage and said first and second voltage sources.

Claim 11

A substantially constant capacitance for increasing the frequency of a transconductance amplifier having at least a circuit for producing an output current from an output voltage and having a predetermined gain, said circuit comprising: means for receiving an input voltage and for producing the output voltage in response to said input voltage, said means for receiving having a positive input terminal for receiving said input voltage and a negative input terminal for receiving a reference voltage, operatively connected, respectively, to first and second semiconductor means for accepting the input voltage and reference voltage received on said positive and negative input terminals; means for setting the gain of the transconductance amplifier and operatively connected to said means for receiving; and variable means for increasing the frequency response of the transconductance amplifier by providing a substantially constant capacitance across the means for setting the gain and operatively connected to said means for receiving and to said means for setting the gain and which is unaffected by changes in the level of said input voltage, said variable means for increasing the frequency response comprising a first variable voltage source operatively connected to said first semiconductor means and a second variable voltage source operatively connected to said second semiconductor means and first, second, third and fourth reverse biased diodes, said first diode connected across said first voltage source and said fourth diode connected across said second voltage source, said second diode connected from one side of said first voltage source to the opposed side of said second voltage source and said third diode connected between said first and second voltage sources in an opposite configuration to said second diode, said first, second, third and fourth diodes connected to be reversed biased by said input voltage, said reference voltage and said first and second voltage sources.

Claim 12

The circuit described in claim 6 wherein when said first and second voltage sources are changed in voltage level at substantially the same time the voltage level across each of said diodes is changed by substantially the same degree.

Claim 13

A substantially constant capacitance for increasing the frequency of a transconductance amplifier having at least a circuit for producing an output current from an output voltage and having a predetermined gain, said circuit comprising: means for receiving an input voltage and for producing the output voltage in response to said input voltage, said means for receiving having a positive input terminal for receiving a positive portion of said input voltage and a negative input terminal for receiving a reference negative portion of said input voltage, operatively connected, respectively, to first and second semiconductor means for accepting the positive and negative portions of said input voltage received on said positive and negative input terminals; means for setting the gain of the transconductance amplifier and operatively connected to said means for receiving; and variable means for increasing the frequency response of the transconductance amplifier by providing a substantially constant capacitance across the means for setting the gain and operatively connected to said means for receiving and to said means for setting the gain and which is unaffected by changes in the level of said input voltage, said variable means for increasing the frequency response comprising a first variable voltage source operatively connected to said first semiconductor means and a second variable voltage source operatively connected to said second semiconductor means and first, second, third and fourth reverse biased diodes, said first diode connected across said first voltage source and said fourth diode connected across said second voltage source, said second diode connected from one side of said first voltage source to the opposed side of said second voltage source and said third diode connected between said first and second voltage sources in an opposite configuration to said second diode, said first, second, third and fourth diodes connected to be reversed biased by said positive and negative portions of said input voltage and by said first and second voltage sources.

Claim 14

A substantially constant capacitance for increasing the frequency of a transconductance amplifier having at least a circuit for producing an output current from an output voltage and having a predetermined gain, said circuit comprising: means for receiving an input voltage and for producing the output voltage in response to said input voltage, said means for receiving having a positive input terminal for receiving a positive portion of said input voltage and a negative input terminal for receiving a reference negative portion of said input voltage, operatively connected, respectively, to first and second semiconductor means for accepting the positive and negative portions of said input voltage received on said positive and negative input terminals; means for setting the gain of the transconductance amplifier and operatively connected to said means for receiving; and variable means for increasing the frequency response of the transconductance amplifier by providing a substantially constant capacitance across the means for setting the gain and operatively connected to said means for receiving and to said means for setting the gain and which is unaffected by changes in the level of said input voltage, said variable means for increasing the frequency response comprising a first variable voltage source operatively connected to said first semiconductor means and a second variable voltage source operatively connected to said second semiconductor means and first, second, third and fourth reverse biased diodes, said first diode connected across said first voltage source and said fourth diode connected across said second voltage source, said second diode connected from one side of said first voltage source to the opposed side of said second voltage source and said third diode connected between said first and second voltage sources in an opposite configuration to said second diode, said first, second, third and fourth diodes connected to be reversed biased by said positive and negative portions of said input voltage and by said first and second voltage sources.

Claim 15

The circuit described in claim 8 wherein when said first and second voltage sources are changed in voltage level at substantially the same time the voltage level across each of said diodes is changed by substantially the same degree.

Claim 16

A substantially constant capacitance circuit for increasing the frequency response of a transconductance amplifier having at least a circuit for producing an output current from an output voltage and having a predetermined gain, said circuit comprising: first semiconductor means for accepting an input voltage and producing the output voltage having a positive input terminal for receiving said input voltage; second semiconductor means for accepting a reference voltage and also producing the output voltage having a negative input terminal for receiving said reference voltage, operatively connected by a gain setting resistor to said first semiconductor means; first variable voltage source operatively connected to said first semiconductor means and second variable voltage source operatively connected to said second semiconductor means; first, second, third and fourth reversed biased diodes, said first diode connected across said first voltage source and said fourth diode connected across said second voltage source, said second diode connected from one side of said first voltage source to the opposite side of said second voltage source and said third diode connected between said first and second voltage sources in an opposite configuration to said second diode, said first, second, third and fourth diodes connected to be reversed biased by said input voltage, said reference voltage and said first and second voltage sources, said voltage sources and said reversed biased diodes also being connected across said gain setting resistor.

Claim 17

A substantially constant capacitance circuit for increasing the frequency response of a transconductance amplifier having at least a circuit for producing an output current from an output voltage and having a predetermined gain, said circuit comprising: first semiconductor means for accepting an input voltage and producing the output voltage having a positive input terminal for receiving said input voltage; second semiconductor means for accepting a reference voltage and also producing the output voltage having a negative input terminal for receiving said reference voltage, operatively connected by a gain setting resistor to said first semiconductor means; first variable voltage source operatively connected to said first semiconductor means and second variable voltage source operatively connected to said second semiconductor means; first, second, third and fourth reversed biased diodes, said first diode connected across said first voltage source and said fourth diode connected across said second voltage source, said second diode connected from one side of said first voltage source to the opposite side of said second voltage source and said third diode connected between said first and second voltage sources in an opposite configuration to said second diode, said first, second, third and fourth diodes connected to be reversed biased by said input voltage, said reference voltage and said first and second voltage sources, said voltage sources and said reversed biased diodes also being connected across said gain setting resistor.

Claim 18

A substantially constant capacitance circuit for increasing the frequency response of a transconductance amplifier having at least a circuit for producing an output current from an output voltage and having a predetermined gain, said circuit comprising: first semiconductor means for accepting the positive portion of an input voltage and producing the output voltage, having a positive input terminal for receiving said positive portion of said input voltage; second semiconductor means for accepting the negative portion of said input voltage and also producing the output voltage, having a negative input terminal for receiving said negative portion of said input voltage, operatively connected by a gain setting resistor to said first semiconductor means; first variable voltage source operatively connected to said first semiconductor means; second variable voltage source operatively connected to said second semiconductor means; first, second, third and fourth reversed biased diodes, said first diode connected across said first voltage source and said fourth diode connected across said second voltage source, said second diode connected from one side of said first voltage source to the opposite side of said second voltage source and said third diode connected between said first and second voltage sources in an opposite configuration to said second diode, said first, second, third and fourth diodes connected to be reversed biased by said positive and negative portions of said input voltage and by said first and second voltage sources, said voltage sources and said reversed biased diodes also being connected across said gain setting resistor.

Claim 19

A substantially constant capacitance circuit for increasing the frequency response of a transconductance amplifier having at least a circuit for producing an output current from an output voltage and having a predetermined gain, said circuit comprising: first semiconductor means for accepting the positive portion of an input voltage and producing the output voltage, having a positive input terminal for receiving said positive portion of said input voltage; second semiconductor means for accepting the negative portion of said input voltage and also producing the output voltage, having a negative input terminal for receiving said negative portion of said input voltage, operatively connected by a gain setting resistor to said first semiconductor means; first variable voltage source operatively connected to said first semiconductor means; second variable voltage source operatively connected to said second semiconductor means; first, second, third and fourth reversed biased diodes, said first diode connected across said first voltage source and said fourth diode connected across said second voltage source, said second diode connected from one side of said first voltage source to the opposite side of said second voltage source and said third diode connected between said first and second voltage sources in an opposite configuration to said second diode, said first, second, third and fourth diodes connected to be reversed biased by said positive and negative portions of said input voltage and by said first and second voltage sources, said voltage sources and said reversed biased diodes also being connected across said gain setting resistor.