Constant slew rate circuits

Claim 2

A constant slew rate circuit, which produces an output signal of constant linear slope upon application thereto of a step function input signal of either positive-going or negative-going nature, comprising: a main integrated solid-state amplifier having an inverting input, a noninverting input, and an output; first feedback means comprising a capacitor connected to said output of said main amplifier, a small, nonreactive sensing impedance connected from said capacitor to a plane of reference potential, and an AC rate feedback circuit connected from the common terminal of said capacitor and said sensing impedance to one input of said main amplifier; and second feedback means comprising a negative feedback DC stabilization circuit connected from said main amplifier output to one of said inputs of said main amplifier, said negative feedback circuit having an impedance at least an order of magnitude greater than said sensing impedance.

Claim 3

A constant slew rate circuit according to claim 1 in which said rate feedback circuit inCludes threshold means, symmetrical with respect to signals of opposite polarity, precluding any effective rate-limiting, AC feedback to said main amplifier until the voltage drop across said sensing impedance exceeds a predetermined minimum threshold voltage.

Claim 4

A constant slew rate circuit according to claim 2 in which said threshold means comprises a pair of diodes connected in parallel with each other and in opposed polarities, interposed in said rate feedback circuit, and in which said minimum threshold voltage in the forward breakdown voltage of said diodes.

Claim 5

A constant slew rate circuit according to claim 1 in which said negative feedback DC stabilization circuit comprises a large resistance connected from the output of said main amplifier to said inverting input of said main amplifier.

Claim 6

A constant slew rate circuit according to claim 1 in which said negative feedback DC stabilization circuit comprises a DC amplifier having an input connected to the output of said main amplifier and an output connected to one input of said main amplifier.

Claim 7

A constant slew rate filter according to claim 5 in which said DC amplifier has a parallel RC circuit connected between its input and its output and functions as a low-pass filter, minimizing AC feedback to the main amplifier through the DC feedback circuit.

Claim 8

A constant slew rate filter according to claim 5 in which said DC amplifier includes an AC bypass to a plane of reference potential to preclude AC feedback to the main amplifier through the DC feedback circuit.

Claim 9

A constant slew rate filter according to claim 1 in which said negative DC feedback circuit includes limiting means, symmetrical with respect to signals of opposite polarity, precluding any effective negative DC feedback to said main amplifier until the voltage at the output of said main amplifier exceeds a predetermined minimum threshold voltage.

Claim 10

A constant slew rate circuit according to claim 8 in which said limiting means comprises a pair of diodes connected in parallel with each other and in opposed polarities, interposed in said negative DC feedback circuit, and in which the minimum threshold voltage is the forward breakdown voltage of said diodes.

Claim 11

A constant slew rate circuit according to claim 1 in which said first feedback means includes signal-controlled means for changing the effective impedance of said sensing impedance to thereby adjust the slewing rate of the circuit.

Claim 12

A constant slew rate circuit according to claim 10 in which said sensing impedance comprises a sensing resistor and in which said signal-controlled means comprises a semiconductor discharge device having input and output electrodes connected in parallel with said sensing resistor and having a control electrode for receiving a control signal to vary the conductivity of said device and thereby vary the total effective impedance between said capacitor and said plane of reference potential.

Claim 13

A constant slew rate circuit according to claim 11 in which said discharge device is a field-effect transistor.

Claim 14

A constant slew rate circuit according to claim 1 in which said sensing impedance comprises: a second integrated solid-state amplifier having an inverting input, a noninverting input, and an output, one input of said second amplifier being connected to said capacitor, the other input of said second amplifier being connected to said plane of reference potential, and the output of said second amplifier being connected back to one input of said main amplifier; and a resistor connected between said one input and said output of said second amplifier.

Claim 15

A constant slew rate circuit according to claim 13 in which said rate feedback circuit includes threshold means precluding any effective rate-limiting AC feedback to said main amplifier until the voltage drop across said sensing impedance exceeds a predetermined minimum threshold voltage.

Claim 16

A constant slew rate circuit according to clAim 14 in which said threshold means comprises a pair of diodes connected in parallel with each other and in opposed polarities, interposed in said rate feedback circuit, and in which said minimum threshold voltage is the forward breakdown voltage of said diodes.

Claim 17

A constant slew rate circuit according to claim 1, and further comprising an additional integrated solid-state amplifier having an output connected to one input of said main amplifier and having an input connected to said output of said main amplifier, said main amplifier affording a negative feedback circuit for said additional amplifier to provide a differentiating circuit.

Claim 18

A constant slew rate circuit according to claim 2 and further including an output compensation stage, comprising a differential adding circuit, having two inputs, one connected to the output of said main amplifier and the other to said rate feedback circuit, to compensate for variations in the output of said circuit introduced by the presence of said threshold means in said rate feedback circuit.

Claim 19

A constant slew rate circuit according to claim 17, in which said output compensation stage comprises a second integrated solid-state amplifier, and said two inputs to said compensation stage comprise inverting and noninverting input terminals for said second amplifier.

Claim 20

A constant slew rate circuit according to claim 18, in which the inverting input to said second amplifier is connected to the output of said main amplifier through a first resistor and the noninverting input to said second amplifier is connected to said rate feedback circuit through a second resistor and to system ground through a third resistor, all three resistors being of equal resistance.

Claim 21

A wave-shaping circuit for converting an input signal of rectangular waveform to an output signal of sinusoidal waveform, with zero phase distortion, over a wide range of input frequencies, comprising a first stage for converting said rectangular waveform input signal to an intermediate signal of triangular waveform and a second stage for converting said triangular waveform intermediate signal to a sinusoidal output signal, at least one of said first and second stages being a constant slew rate circuit comprising: an integrated solid-state amplifier having an inverting input, a noninverting input, and an output; first feedback means comprising a capacitor connected to said output of said amplifier, a low, nonreactive sensing impedance connected from said capacitor to a plane of reference potential, and a rate-limiting AC feedback circuit connected from the common terminal of said capacitor and said sensing impedance to one input of said amplifier; and second feedback means comprising a negative feedback DC stabilization circuit connected from said amplifier output to one of said inputs of said amplifier, said negative feedback circuit having an impedance at least an order of magnitude greater than said sensing impedance.

Claim 22

A wave-shaping circuit for converting an input signal of rectangular waveform to an output signal of sinusoidal waveform, with zero phase distortion, over a wide range of input frequencies, comprising a first stage for converting said rectangular waveform input signal to an intermediate signal of triangular waveform and a second stage for converting said triangular waveform intermediate signal to a sinusoidal output signal, at least one of said first and second stages being a constant slew rate circuit comprising: an integrated solid-state amplifier having an inverting input, a noninverting input, and an output; first feedback means comprising a capacitor connected to said output of said amplifier, a low, nonreactive sensing impedance connected from said capacitor to a plane of reference potential, and a rate-limiting AC feedback circuit connected from the common terminal of said capacitor and said sensing impedance to one input of said amplifier; and second feedback means comprising a negative feedback DC stabilization circuit connected from said amplifier output to one of said inputs of said amplifier, said negative feedback circuit having an impedance at least an order of magnitude greater than said sensing impedance.

Claim 23

A wave-shaping circuit according to claim 20, in which said constant slew rate circuit comprises the first stage of said wave-shaping circuit and said second stage comprises: an integrated solid-state second stage amplifier having at least one input terminal and an output terminal; an input circuit comprising a pair of diodes connected in parallel with each other from said input terminal to a shunt input resistance, said shunt input resistance being returned to a plane of reference potential; and a bias resistance connected from the common terminal of said diodes and said shunt input impedance to said output terminal of said second stage amplifier.

Claim 24

A wave-shaping filter for converting an input signal of triangular waveform to an output signal of sinusoidal waveform, with zero phase distortion and without substantial loss of amplitude information, comprising: an integrated solid-state amplifier having at least one input terminal and an output terminal; an input circuit comprising a pair of diodes connected in parallel with each other from said input terminal to a shunt input resistance, said shunt input resistance being returned to a plane of reference potential; and a bias resistance connected from the common terminal of said diodes and said shunt input impedance to said output terminal of said amplifier.

Claim 25

A wave-shaping filter for converting an input signal of triangular waveform to an output signal of sinusoidal waveform, with zero phase distortion and without substantial loss of amplitude information, comprising: an integrated solid-state amplifier having at least one input terminal and an output terminal; an input circuit comprising a pair of diodes connected in parallel with each other from said input terminal to a shunt input resistance, said shunt input resistance being returned to a plane of reference potential; and a bias resistance connected from the common terminal of said diodes and said shunt input impedance to said output terminal of said amplifier.

Claim 26

A wave-shaping filter according to claim 22, in which said amplifier has an inverting input terminal and a noninverting input terminal, in which said input circuit is connected to the noninverting input terminal of said amplifier, and in which said inverting input terminal is returned to said plane of reference potential.

Claim 27

A signal processing circuit comprising: a solid-state amplifier having an input and an output; rate-sensing means, comprising a low, nonreactive impedance AC coupled to the output of said amplifier and connected to a plane of reference potential, for developing a rate-limiting signal representative of the rate of change of the output signal voltage from said amplifier; and negative feedback means coupling said rate-sensing means to the input of said amplifier to limit the output signal voltage of said amplifier to a predetermined constant rate of change for both positive-going and negative-going signals.

Claim 28

A signal processing circuit comprising: a solid-state amplifier having an input and an output; rate-sensing means, comprising a low, nonreactive impedance AC coupled to the output of said amplifier and connected to a plane of reference potential, for developing a rate-limiting signal representative of the rate of change of the output signal voltage from said amplifier; and negative feedback means coupling said rate-sensing means to the input of said amplifier to limit the output signal voltage of said amplifier to a predetermined constant rate of change for both positive-going and negative-going signals.

Claim 29

A signal processing circuit according to claim 24 in which said feedback means includes threshold means precluding any effective rate-limiting feedback to the input of said amplifier until the rate of change of said given parameter of the output signal from said amplifier exceeds a given threshold rate, whereby said circuit operates as a faithful follower for input signals having a rate of change below a given value and as a constant slew rate circuit for input signals having a rate of change exceeding said given value.