Ramped-step signal generating circuit

Claim 2

A signal generator for producing a step signal having ramps between successive step levels, said signal generator comprising: means for generating only a step signal having a plurality of successive step levels wherein each step level is a discrete voltage level; means for generating linear ramps between the successive step levels of said step signal, said ramp generating means comprising: two equal constant current sources of opposite polarity, each connected to a common junction; control means, responsive to each successive step level change for selectively opening only one of said current sources at a time, said control means having an inverting input and a noninverting input, said inverting input being connected to said step signal generating means; a capacitOr with a first terminal connected to the junction of said current sources and a second terminal of said capacitor connected to a reference potential so as to charge or discharge depending on which current source is selectively opened by said control means; and a feedback path for feeding back a signal indicative of the voltage charge on said capacitor, said feedback path connected to said non-inverting input of said control means whereby the signal indicative of the voltage charge is not inverted through said control means.

Claim 3

The apparatus of claim 1 wherein the first constant current source comprising: isolating and switch means, responsive to said control means, for disconnecting the first current source from the junction between current sources when the signal from said control means is of a first polarity; and the second constant current source comprises: isolating and switch means, responsive to said control means, for disconnecting the second current source from the junction between current sources when the signal from said control means is of a second polarity.

Claim 4

The apparatus of claim 2 wherein the said control means is a control amplifier; said current sources are connected between equal and opposite supply voltage sources; and said reference potential comprises a first terminal of a resistor having a second terminal which connects to zero volts.

Claim 5

The apparatus of claim 3 wherein each of said current sources further comprises a resistor with a first terminal connected to a respective one of said supply voltage sources; differential voltage source means, reference to said respective supply voltage source, and connected to said isolating and switch means, said isolating and switch means being operative to connect said differential voltage source means to a second terminal of said resistor and for connecting said second resistor terminal to said junction in response to said control amplifier.

Claim 6

The apparatus of claim 4 wherein said differential voltage source means comprises a zener diode; said isolating and switch means comprise a single transistor; and said control amplifier is connected to both of said transistors through respective resistors.

Claim 7

The apparatus of claim 5 wherein said feedback path comprises a buffer amplifier connected to said capacitor to provide a signal representative of capacitor voltage to said control amplifier.

Claim 8

A signal generator for generating a step signal having ramps between successive step levels, said signal generator comprising: means for generating a step signal having a plurality of successive step levels wherein each step level is a discrete voltage level; and means for generating linear ramps between the successive step levels of said step signal, said ramp generating means comprising: a first constant voltage source and a second constant voltage source of opposite polarity to said first constant voltage source; a capacitor; a first constant current path connecting said first constant voltage source to said capacitor, said first current path comprising a first switching transistor for switching said current path on or off; a second constant current path connecting said second voltage source to said capacitor, said second current path comprising a second switching transistor for switching said second current path on or off; a differential amplifier having an inverting and a non-inverting input wherein said inverting input receives discrete voltage levels from the step signal generated by said step signal generating means, said differential amplifier has an output which is connected to the control electrodes of said first and second switching transistors, and said first and second transistors are alternately conductive in response to the polarity of the signal present on the single output of said differential amplifier which causes only one of said switching transistors to be switched on; and a feedback path connected tO the capacitor for feeding back a signal indicative of a capacitor voltage to said non-inverted feedback signal indicative of capacitance voltage and the inverted input of discrete changes.

Claim 9

A signal generator for generating a step signal having ramps between successive step levels, said signal generator comprising: means for generating a step signal having a plurality of successive step levels wherein each step level is a discrete voltage level; and means for generating linear ramps between the successive step levels of said step signal, said ramp generating means comprising: a first constant voltage source and a second constant voltage source of opposite polarity to said first constant voltage source; a capacitor; a first constant current path connecting said first constant voltage source to said capacitor, said first current path comprising a first switching transistor for switching said current path on or off; a second constant current path connecting said second voltage source to said capacitor, said second current path comprising a second switching transistor for switching said second current path on or off; a differential amplifier having an inverting and a non-inverting input wherein said inverting input receives discrete voltage levels from the step signal generated by said step signal generating means, said differential amplifier has an output which is connected to the control electrodes of said first and second switching transistors, and said first and second transistors are alternately conductive in response to the polarity of the signal present on the single output of said differential amplifier which causes only one of said switching transistors to be switched on; and a feedback path connected tO the capacitor for feeding back a signal indicative of a capacitor voltage to said non-inverted feedback signal indicative of capacitance voltage and the inverted input of discrete changes.

Claim 10

The signal generator of claim 7 wherein the first and second current paths and the feedback path are all commonly connected to a first terminal of said capacitor and a second terminal of said capacitor is connected through a resistor to a zero voltage potential.

Claim 11

The signal generator of claim 8 wherein said feedback path comprises a buffer amplifier connected to said first terminal of said capacitor.