CN1206248A - Simple voltage-to-current converting circuit with wide control range - Google Patents
Simple voltage-to-current converting circuit with wide control range Download PDFInfo
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- CN1206248A CN1206248A CN 98102425 CN98102425A CN1206248A CN 1206248 A CN1206248 A CN 1206248A CN 98102425 CN98102425 CN 98102425 CN 98102425 A CN98102425 A CN 98102425A CN 1206248 A CN1206248 A CN 1206248A
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Abstract
A voltage-to-current converter is implemented by a series of a load transistor, an output node and an n-channel depletion type field effect transistor applied with a voltage control signal; when the voltage control signal is zero, the n-channel enhancement type field effect transistor flows certain drain current equivalent to standard biasing current; when the voltage control signal is increased from zero to a positive level, the n-channel enhancement type depletion transistor immediately increases drain current so as to achieve a wide control range.
Description
The present invention relates to a kind of current/charge-voltage convertor, and be particularly related to a kind of simple current/charge-voltage convertor that is suitable for being assembled in the voltage-controlled oscillator in the phase-locked loop.
The typical case of a phase-locked loop is disclosed among the unexamined Japanese patent gazette application number No.6-283994, and Fig. 1 shows this phase-locked loop.This phase-locked loop comprises a phase-frequency detector 1, a supply pump 2, a loop filter 3, a voltage-controlled oscillator 4 and a frequency divider 5.Phase frequency control detection device 1 is abbreviated as " PFD " in Fig. 1.
Phase-frequency detector 1 has two input nodes, and oscillating signal OSC1 and clock signal clk 1 are added on two input nodes of phase-frequency detector 1.Whether phase-frequency detector is made comparisons oscillating signal OSC1 and clock signal clk 1, look its mutual phase place and frequency and mate.If oscillating signal OSC1 lags behind clock signal clk 1, phase-frequency detector 1 just provides an expression to quicken the first control signal CTL1 of vibration instruction to supply pump 2.On the other hand, if oscillating signal OSC1 is leading, phase-frequency detector then provides the second control signal CTL2 of the contrary instructions of an expression deceleration vibration to supply pump 2.
Though do not give expression in the accompanying drawings, loop filter 3 comprises a low pass filter and a capacitor, and makes control voltage signal CTL3 stable.The level of 4 pairs of control of voltage-controlled oscillator voltage signal CTL3 responds and changes the frequency of oscillator signal OSC2, and oscillator signal OSC2 is offered an internal circuit (not shown) and frequency divider 5.
Fig. 2 illustrates voltage-controlled oscillator 4.Voltage-controlled oscillator 4 mainly comprises a voltage-current converter 4a and a current control oscillator 4b.Current control oscillator 4b is abbreviated as " ICO " in Fig. 1 and 2, and produces a bias current signal BS1 by control voltage signal CTL3.Current control oscillator 4b changes the frequency of oscillator signal OSC2 with bias current signal BS1.
Voltage-current converter 4a comprises that one is connected the constant-current source 4c between power supply 4d and the ground wire GND, between power supply 4f and constant-current source 4c, connect a P-channel enhancement type field-effect transistor 4e, and between output node 4h and ground wire GND, connect a n channel enhancement field-effect transistor 4g.Bias current signal BS1 offers current control oscillator 4b by output node.
Constant-current supply 4c comprises the polyphone combination of the resistance 4j that is connected between power supply 4d and the ground wire GND and n channel enhancement field-effect transistor 4k and is connected a n channel enhancement field-effect transistor 4m between output node 4h and the ground wire GND.The gate electrode of n channel enhancement field-effect transistor 4k links to each other with its drain node N1, and drain node N1 links to each other with the gate electrode of n channel enhancement field-effect transistor 4m.Resistance 4j and n channel enhancement field-effect transistor 4k flow through constant current by power supply 4d to ground wire GND, and make drain node N1 be adjusted to a voltage of determining.This voltage of determining is offered the gate electrode of n channel enhancement field-effect transistor 4m, and expect that n channel enhancement field-effect transistor 4m has the constant current I that flows into ground wire GND
c
P-channel enhancement type field-effect transistor 4e has the gate electrode that links to each other with output node 4h, and presses the level variation channel conduction of output node 4h.P-channel enhancement type field-effect transistor 4e provides electric current to n channel enhancement field-effect transistor 4g/4m, and produces bias current signal BS1.
CTL3 is added on the gate electrode of n channel enhancement field-effect transistor 4g with the control voltage signal, and crosses variable current I according to the amplitude streams of control voltage signal CTL3
vLike this, electric current (I
c+ I
v) total amount just change with control voltage signal CTL3, power voltage line 4f just provides and electric current I to output node
cAnd electric current I
vThe electric current that equates.Bias current signal BS1 determine the to flow through magnitude of current of a constant-current source of current control oscillator 4b, current control oscillator 4b forms a current mirror circuit with P-channel enhancement type field-effect transistor 4e.Current control oscillator 4b is in the frequency place vibration suitable with the magnitude of current that passes through current source.
As previously mentioned, control voltage signal CTL3 is representing the phase difference between oscillating signal OSC1 and the clock signal clk 1.When oscillating signal OSC1 and clock signal clk 1 were same-phase signal, control voltage signal CTL3 just remained on 0 volt, and n channel enhancement field-effect transistor 4g then turn-offs.Only there is constant-current source 4c to flow into constant current I to ground wire GND
c, and bias current signal BC1 causes that current control oscillator 4b vibrates in free oscillation frequency.On the other hand, when producing phase difference, control voltage signal CTL3 causes that n channel enhancement field-effect transistor 4g flows through variable current I
v, and voltage-current converter 4a changes the bias current signal.For this reason, in Fig. 3, represent the voltage-to-current transfer characteristic with curve A.
An intrinsic problem among the prior art voltage-current converter 4a is that control range " a " is narrow.This is owing in fact equal the threshold voltage V of n channel enhancement field-effect transistor 4g at control voltage signal CTL3
ThThe time n channel enhancement field-effect transistor 4g just begin to flow through variable current I
vIn other words, voltage-current converter 4a reaches the threshold value V of n channel enhancement field-effect transistor 4g at control voltage signal CTL3
ThControl voltage signal CTL3 is not responded before.
Another intrinsic problem among the prior art voltage-current converter 4a is a large amount of circuit element.Constant-current source 4c and n channel enhancement field-effect transistor 4g are connected in parallel between output node 4h and the ground wire GND, and constant-current source 4c needs resistance 4j and two field-effect transistor 4k/4m.However, because constant current I
cDetermine the free oscillation frequency of oscillator 4b, thereby constant-current source 4c is still for the voltage-current converter 4a of prior art indispensable.
A free-revving engine of the present invention is that a kind of voltage-current converter will be provided, and it has broad control range and simple circuit configuration.
In order to realize purpose of the present invention, proposed to make a depletion mode fet to flow through a constant current, and need not gate bias to be set for free oscillation frequency.
According to a kind of mode of the present invention, the voltage-current converter that is provided comprise be connected between first power supply and the output node in order to a load elements that electric current is provided to output node and be connected output node and second source between and the current control transistor realized with a depletion mode fet, with this to control voltage signal from a standard bias level change change that responds flow through wherein electric current.
From below in conjunction with the feature and advantage that will become apparent voltage-current converter of the present invention the explanation that accompanying drawing carried out, wherein:
Fig. 1 is the block diagram of expression prior art phase-locked loop circuit structure;
Fig. 2 is assembled in the circuit diagram of the structure of the voltage-controlled oscillator in the prior art phase-locked loop for expression;
Fig. 3 is the curve chart of the voltage-to-current transfer characteristic of the voltage-to-current transfer characteristic of expression prior art voltage-current converter and voltage-current converter of the present invention;
Fig. 4 is the circuit diagram of the structure of expression voltage-current converter of the present invention; And
Fig. 5 is the circuit diagram of the structure of the voltage-current converter of expression one modification.
Consult Fig. 4 of accompanying drawing, embody a voltage-current converter 10a of the present invention and form a voltage-controlled oscillator 10 with a current control oscillator 10b.Although voltage-controlled oscillator 10 forms parts of phase-locked loop, other parts of phase-locked loop are similar with the phase-locked loop of prior art, thereby still represent with the same numeral among Fig. 1 in the explanation afterwards.
Following description focuses on the structure and the performance of voltage-current converter.Voltage-current converter 10a realizes that with the tandem compound of a P-channel enhancement type field-effect transistor 10c and a n channel depletion type field-effect transistor 10d this tandem compound is connected between a positive supply 10e and the ground wire 10f.P-channel enhancement type field-effect transistor 10c has a gate electrode that links to each other with output node 10g, and will control on the gate electrode that voltage signal CTL3 is added to n channel depletion type field-effect transistor 10d.N channel depletion type field-effect transistor 10d need not any gate bias or no-voltage just flows through constant leakage current I
c, and along with the amplitude of control voltage signal CTL3 increases leakage current together.Power voltage line 10e provides the electric current that equates with leakage current to output node 10g.Bias current signal BS2 determines to flow through the magnitude of current of the constant-current source of current control oscillator 4b, and current control oscillator 4b forms a current mirror circuit with P-channel enhancement type field-effect transistor 10c.Current control oscillator 4b vibrates at a frequency place suitable with the magnitude of current that flows through current source.
Will be appreciated that from the explanation of front n channel depletion type field-effect transistor 10d not only determines the constant current I of free oscillation frequency
c, but also the frequency of change oscillator signal OSC2.In other words, n channel depletion type field-effect transistor 10d is realizing two kinds of functions of constant-current source 4c and n channel enhancement field-effect transistor 4g.Consequently, simplify the circuit structure of voltage-current converter 10a, and reduced the parts number of parts in large quantities.In the case, P-channel enhancement type field-effect transistor 10c is as a load elements.
P-channel enhancement type field-effect transistor 10c provides leakage current through output node 10g to n channel depletion type field-effect transistor 10d, and bias current signal BS2 then offers current control oscillator 10b from output node 10g.
When oscillating signal OSC1 and clock signal clk 1 same-phase, control voltage signal CTL3 remains on zero volt, and n channel depletion type field-effect transistor 10d then flows through constant leakage current I under the state that does not have biasing
cThen, bias current signal BS2 makes current control oscillator 10b vibrate at the free oscillation frequency place.
On the other hand, if phase difference occurs between oscillating signal OSC1 and clock signal clk 1, supply pump 2 just increases the amplitude of control voltage signal CTL3, so, make n channel depletion type field-effect transistor 10d increase channel conduction.Consequently, bias current signal BS2 has reduced current potential, and current control oscillator 10b makes oscillator signal OSC2 in advance.Thereby the voltage-current characteristic of transducer 10a just represents with curve B that control range then is increased to " b " from " a ".
Because the control range broadness, voltage-current converter 10a is suitable for voltage-controlled oscillator 10.Because circuit element is reduced to unlike prior art, voltage-current converter 10a is hopeful to be used for a kind of integrated circuit.
When the frequency ratio " n " between oscillator signal OSC1 and the oscillating signal OSC2 is two, phase-locked loop with voltage-current converter assembling of the present invention is suitable for doubling the data transferring technique of ratio, and can form for example part of the high speed semiconductor memory device of synchronous dram (dynamic random access memory) device and so on.
Will be understood that from the explanation of front voltage-current converter of the present invention makes control range broadness and circuit structure simple.
Simple circuit configuration makes the electric current that expends be reduced to half that the prior art voltage-current converter expends electric current.
Because it is little to form the part member quantity of voltage-current converter, the less influence that is subjected to the characteristics of transistor fluctuation of voltage-current converter of the present invention.The free oscillation frequency fluctuation is little, makes the designer can determine the minimum frequency of oscillation of low-frequency oscillation.
Although represented and described a certain embodiments of the present invention, for the professional and technical personnel, they will be appreciated that, can make diversiform change and modification without departing from the spirit and scope of the present invention.
For example, can use the P channel depletion type field-effect transistor shown in Fig. 5.In this case, voltage control signal CTL3 ' has reduced amplitude from no bias state.
And depletion mode fet 10d/20 can determine the free oscillation frequency under negative/positive bias state.
Claims (11)
1, a kind of voltage-current converter (10a) includes
One is connected between one first power supply (10e) and the output node (10g) in order to the load elements (10c) of electric current to be provided to described output node (10g), and
One is connected between a described output node (10g) and the second source (10f) in order to change the current control circuit of described electric current, and described voltage-current converter (10a) is characterised in that
Described current control circuit is with a depletion mode fet (10d; 20) realize, make its control voltage signal (CTL3 changing from a standard bias level; CTL3 ') responds and change its electric current of flowing through.
2, according to the described voltage-current converter of claim 1, it is characterized in that, bias current signal (BS2) wherein offers a current control oscillator (10b) by described output node (10g), and described bias current signal is determined the free oscillation frequency of described current control oscillator (10b) in described standard bias level.
3, according to the described voltage-current converter of claim 2, it is characterized in that, described current control oscillator (10b) is with described voltage-current converter (10a) formation-voltage-controlled oscillator (10), and described voltage-controlled oscillator forms parts of a phase-locked loop.
According to the described voltage-current converter of claim 3, it is characterized in that 4, described phase-locked loop also comprises
One comparator (1), it carries out operating ratio to one first oscillator signal (OSC1) and a clock signal (CLK1), with a command signal (CTL1/CTL2) of situation between generation described first oscillator signal of expression and the described clock signal,
One voltage signal generation circuit (2/3), it responds to described command signal, produces described control voltage signal (CTL3; CTL3 ').
5, according to described voltage one current converter of claim 4, it is characterized in that, described comparator realizes with a phase-frequency detector (1), and described voltage signal generation circuit then has a supply pump (2) and that links to each other with described phase-frequency detector to be connected loop filter (3) between described supply pump and the described current control transistor.
6, according to the described voltage-current converter of claim 4, it is characterized in that, described phase-locked loop comprises that also one is connected the frequency divider (5) between described voltage-controlled oscillator (10) and the described comparator (1), produces described first oscillator signal (OSC1) in order to one second oscillator signal (OSC2) from described voltage-controlled oscillator output.
According to described voltage one current converter of claim 1, it is characterized in that 7, described depletion mode fet (10d) has the conduction of a n type under described standard bias level.
According to the described voltage-current converter of claim 7, it is characterized in that 8, described standard bias level is zero volt, and described depletion mode fet (10d) flows through a leakage current of determining under described standard bias level.
9, according to the described voltage-current converter of claim 8, it is characterized in that, wherein provide a bias current signal (BS2) to a current control oscillator (10b), and described definite leakage current determines the free oscillation frequency of described current control oscillator (10b) by described output node (10g).
According to the described voltage-current converter of claim 1, it is characterized in that 10, described depletion mode fet (20) has the conduction of a P type under described standard bias level.
According to the described voltage-current converter of claim 1, it is characterized in that 11, described load elements realizes that with a P-channel enhancement type field-effect transistor (10c) it has a gate electrode that links to each other with described output node.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 98102425 CN1206248A (en) | 1997-06-12 | 1998-06-12 | Simple voltage-to-current converting circuit with wide control range |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP155561/97 | 1997-06-12 | ||
| CN 98102425 CN1206248A (en) | 1997-06-12 | 1998-06-12 | Simple voltage-to-current converting circuit with wide control range |
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| Publication Number | Publication Date |
|---|---|
| CN1206248A true CN1206248A (en) | 1999-01-27 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 98102425 Pending CN1206248A (en) | 1997-06-12 | 1998-06-12 | Simple voltage-to-current converting circuit with wide control range |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101551938B (en) * | 2008-12-30 | 2010-12-01 | 上海科达机电控制有限公司 | Voltage-current transformation method |
| CN103582822A (en) * | 2011-03-30 | 2014-02-12 | 电力电子测量有限公司 | Apparatus for current measurement |
| CN103731099A (en) * | 2012-10-11 | 2014-04-16 | 联发科技（新加坡）私人有限公司 | Voltage-to-current converter and voltage controlled oscillator |
| CN108874008A (en) * | 2018-06-22 | 2018-11-23 | 佛山科学技术学院 | A kind of LDO circuit with double feedbacks |
| CN111124024A (en) * | 2019-12-10 | 2020-05-08 | 洛阳隆盛科技有限责任公司 | Low-power 0V starting linear power supply circuit |
-
1998
- 1998-06-12 CN CN 98102425 patent/CN1206248A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101551938B (en) * | 2008-12-30 | 2010-12-01 | 上海科达机电控制有限公司 | Voltage-current transformation method |
| CN103582822A (en) * | 2011-03-30 | 2014-02-12 | 电力电子测量有限公司 | Apparatus for current measurement |
| CN103582822B (en) * | 2011-03-30 | 2016-09-14 | 电力电子测量有限公司 | Equipment for current measurement |
| CN103731099A (en) * | 2012-10-11 | 2014-04-16 | 联发科技（新加坡）私人有限公司 | Voltage-to-current converter and voltage controlled oscillator |
| CN108874008A (en) * | 2018-06-22 | 2018-11-23 | 佛山科学技术学院 | A kind of LDO circuit with double feedbacks |
| CN111124024A (en) * | 2019-12-10 | 2020-05-08 | 洛阳隆盛科技有限责任公司 | Low-power 0V starting linear power supply circuit |
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Owner name: NEC ELECTRONICS TAIWAN LTD. Free format text: FORMER OWNER: NIPPON ELECTRIC CO., LTD. Effective date: 20030509 |
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