CN106961255A - The operational amplifier of programmable output Slew Rate - Google Patents

Abstract

The present invention relates to electronic device, to realize that its programmable Slew Rate is designed by the way that the bias current programming to amplifier is adjustable, flexibility and the versatility of amplifier are improved.The technical solution adopted by the present invention is, the operational amplifier of programmable output Slew Rate, the operational amplifier of programmable output Slew Rate, it is made up of amplifying triode and biasing circuit, metal-oxide-semiconductor is biased in biasing circuit to realize using multiple metal-oxide-semiconductors, whether the conducting of each metal-oxide-semiconductor depends on its controlling switch, and different switch conduction combinations realize the change of total bias current to realize that amplifier exports the programmable change of Slew Rate.Manufactured present invention is mainly applied to electronic device especially Design of Amplifiers.

Description

The operational amplifier of programmable output Slew Rate

Technical field

The present invention relates to electronic device, more particularly to operational amplifier therein, specifically, it is related to programmable output Slew Rate Operational amplifier.

Background technology

Operational amplifier, using extremely wide, generally collectively constitutes certain work(in side circuit design with reference to feedback network Energy module, it is a kind of amplifier with special Coupling circuit and feedback.In sound, the collection of vision signal, handle and logical Believe systematic difference, it is desirable to which amplifier unity gain bandwidth is big, slew rate is high, setup time is short.In recent years, after with circuit system The performance of end component is obviously improved, and occupies the amplifier of signal chains front end in order to matched, it is to avoid tie down the entirety of signal chains Performance, increasingly tends to develop to the direction of high speed, and high pressure Slew Rate is one of principal character of high speed amplifier.At present simultaneously With SOC's (System On Chip)Integrated levelWith continuing to develop for performance, to the power consumption requirements more and more higher of chip, circuit In the too high life and reliability that can make product of electric current reduce.In general, slew rate is highAmplifier, its operating current also gets over Greatly, i.e., power consumption is also bigger.

During high speed operational amplifier design, big signal fast charging and discharging characteristic becomes the pass considered for a necessary emphasis Key factor, its measurement index is referred to as Slew Rate (Slew-Rate, SR).The Slew Rate of usual amplifier is limited to load capacitance size C_L And the maximum charging and discharging currents size I that amplifier can be provided_max：

Therefore the higher amplifier of Slew Rate is exported in the case where load is fixed in actual design process and then requires circuit Maximum charging and discharging currents are bigger, and amplifier is to the bias current that the maximum charging and discharging currents of load are usually amplifier, and its size is main Determine the operating current of amplifier, i.e. amplifier overall power.The MOS ginsengs for being biased to electric current are provided during traditional operational amplifier design Number is just immutable after being normally set up, i.e., its maximum charging and discharging currents provided is fixed value, can not be entered according to the actual requirements Row regulation, too small electric current can cause amplifier speed too low, and excessive electric current can cause power consumption too high.For needing different charge and discharges The amplifier of electric current needs to redesign its inner parameter, and the versatility of amplifier and flexibility are relatively low.To improve amplifier Flexibility to loading impulse electricity ability, a kind of operational amplifier design of programmable Slew Rate based on traditional operational amplifier design herein can root Factually border driving force and system speed demand are carried out from main regulation.

Bibliography：

1、《The dynamic slew rate enhancing circuit research of high speed, low-power consumption under bulky capacitor load》Ye Zhenhua, Yang Haigang, Li Fan Sun, Cheng little Yan, Yin Tao, Liu Fei；Microelectronics and computer, the 12nd phase of volume 29 in 2012.

2nd, Phillip E.A, Douglas R.H.CMOS Analog Circuit Design [M] .New York： OXRORD UNIVERSITY PRESS, 2011.

The content of the invention

To overcome the deficiencies in the prior art, it is contemplated that realizing that it can be compiled by the way that the bias current programming to amplifier is adjustable Journey Slew Rate is designed, and improves flexibility and the versatility of amplifier.The technical solution adopted by the present invention is to may be programmed the fortune of output Slew Rate Amplifier is calculated, the operational amplifier of output Slew Rate is may be programmed, is made up of amplifying triode and biasing circuit, is biased in biasing circuit Metal-oxide-semiconductor realizes whether the conducting of each metal-oxide-semiconductor depends on its controlling switch, and different switch conduction combinations are real using multiple metal-oxide-semiconductors The change of now total bias current is so as to realize that amplifier exports the programmable change of Slew Rate.

Exporting step response is：

In formula, u (t) is unit step signal, V₀For the amplitude of input step signal, A is the open-loop gain of amplifier, R_out For amplifier output resistance, R₁And R₂For the resistance being serially connected between amplifier output end and ground, C_LFor load.

The features of the present invention and beneficial effect are：

Operational amplifier, using extremely wide, generally collectively constitutes certain work(in side circuit design with reference to feedback network Energy module, in big signal processing circuit, the requirement to Slew Rate is higher, and traditional amplifier output Slew Rate is fixed value, With occasion change when need to redesign amplifier, flexibility is relatively low, and the programmable output Slew Rate that designs herein is transported Put achievable amplifier Slew Rate programming adjustable, the size of Slew Rate is selected according to the requirement of practical situations and combination power consumption, is had Very strong flexibility and versatility.

Brief description of the drawings：

Fig. 1 typical case's amplifier application circuits.

Fig. 2 CMOS amplifier overall applicability circuits.

Fig. 3 programmable switches are designed.

Fig. 4 integrally may be programmed the operational amplifier design of output Slew Rate.

Embodiment

The present invention realizes that amplifier output slew rate programming is adjustable, improves amplifier and use by improving conventional operational amplifiers Versatility and flexibility, can be according to carrying out encoding setting to the demand of amplifier power consumption and speed in practical application.

The amplifier used in feedback circuit can show the large signal characteristic of a kind of " conversion ", and Fig. 1 is typical case with feedback The amplifier application circuit structure of network, R₁And R₂Constitute feedback network, C_LFor load, for small step input signal, it is exported Step response is：

In formula, u (t) is unit step signal, V₀For the amplitude of input step signal, A is the open-loop gain of amplifier, R_out For amplifier output resistance.Above formula shows that the Slew Rate of output signal is proportional to the end value of output, and this respond style is referred to as linearly Stable, main cause is that input step signal is smaller, and amplifier does not show the large signal characteristic " changed " also.When the width of input Value increase, the step response of actual discharge circuit begins to deviate from formula (2), and for big input step signal, output is shown not The linear ramp of variable slope.Fig. 2 is the integrated circuit that the amplifier model in Fig. 1 is replaced with CMOS discharge circuits, works as input step Each metal-oxide-semiconductor is operated in saturation region in figure when signal is smaller, can normally realize the amplification of signal, when input signal increases to what is made M₁Absorb I_SSWhole electric currents, thus shut-off M₂, as a result produce slope and be equal to I_SS/C_LSlope output.As long as M₂Maintain shut-off, Feedback control loop is just disconnected, therefore, to C_LCharging current be to maintain constant, and the height nothing of the electric current and incoming level Close, i.e. the Slew Rate of output signal is always I_SS/C_L.Bias current I_SSThe power consumption of whole amplifier is determined simultaneously, therefore circuit is needed Obtaining larger output Slew Rate, then its amplifier overall power can be larger, needs to resit an exam in the high speed circuit for handling big signal Consider the output Slew Rate of signal.The main bias current by amplifier of size in the solid timing output Slew Rate of load can be obtained by Slew Rate formula Determine, therefore the output Slew Rate of amplifier can be changed by changing the bias current of amplifier.The bias current of usual amplifier be by What reference current source was obtained after mirror image, can be programmable defeated so as to realize by programming the bias current of controllable change amplifier Go out the operational amplifier design of Slew Rate, Fig. 3 is to realize programmable offset current methods using switch.Metal-oxide-semiconductor will be biased using switch control Multiple metal-oxide-semiconductors are respectively adopted to realize, whether the conducting of each metal-oxide-semiconductor depends on its controlling switch, and different switch conduction combinations are real The change of now total bias current is so as to realize that amplifier exports the programmable change of Slew Rate.Fig. 4 is overall programmable output Slew Rate Operational amplifier design, switch realized using simple metal-oxide-semiconductor, and the design of whole circuit realizes that amplifier output Slew Rate is programmable to be become Change.

Claims (2)

1. a kind of operational amplifier of programmable output Slew Rate, it is characterized in that, it is made up of, biases amplifying triode and biasing circuit Bias metal-oxide-semiconductor in circuit to realize using multiple metal-oxide-semiconductors, whether the conducting of each metal-oxide-semiconductor depends on its controlling switch, difference switch Conducting combination realizes the change of total bias current to realize that amplifier exports the programmable change of Slew Rate.

2. the operational amplifier of programmable output Slew Rate as claimed in claim 1, it is characterized in that, output step response is：

$V_{out}=V_0\frac{A}{1+A\frac{R_2}{R_1+R_2}}\[1-\exp \frac{-t(1+\frac{{\mathrm{AR}}_2}{R_1+R_2})}{C_L{R}_{out}}\]u\left(t\right)---\left(2\right)$

In formula, u (t) is unit step signal, V₀For the amplitude of input step signal, A is the open-loop gain of amplifier, R_outFor amplifier Output resistance, R₁And R₂For the resistance being serially connected between amplifier output end and ground, C_LFor load.