CN100353661C

CN100353661C - Intermediate frequency reference source

Info

Publication number: CN100353661C
Application number: CNB021377693A
Authority: CN
Inventors: 任建军
Original assignee: Shanghai Huahong Integrated Circuit Co Ltd
Current assignee: Shanghai Huahong Integrated Circuit Co Ltd
Priority date: 2002-10-31
Filing date: 2002-10-31
Publication date: 2007-12-05
Anticipated expiration: 2022-10-31
Also published as: CN1494207A

Abstract

The present invention provides an intermediate frequency reference source used for an integrated circuit. Because the traditional frequency reference source uses a band-gap reference source without a temperature coefficient for providing reference voltage, and the annular oscillator is generally provided with a negative temperature coefficient, the traditional frequency source has the problem of the high reference frequency change. The present invention aims to provide the intermediate frequency reference source with temperature compensation, which comprises a reference voltage source, and an annular oscillator, wherein the reference voltage source is used for outputting the reference voltage and is provided with a positive temperature coefficient, and the annular oscillator is connected with the reference voltage source, receives the reference voltage outputted by the reference voltage source and generates an oscillating signal. The annular oscillator is also provided with a negative temperature coefficient.

Description

IF-FRE a reference source

Technical field

The present invention relates to frequency source, relate in particular to a kind of IF-FRE a reference source that is used for integrated circuit.

Background technology

In many integrated circuits, generally all integrated many various circuit, frequency source is comparatively common a kind of circuit.In the past, just the component frequency source circuit is made in the integrated circuit, and the elements such as capacitor that wherein volume is bigger were with the form setting of outward element.Along with the progress of integrated circuit technology and to the raising of volume requirement, people have set out a kind of (promptly realizing at IC interior) that all is integrated in an IC interior, have not needed the frequency reference source of outward element.

Fig. 1 shows a kind of traditional block diagram in the frequency reference source that IC interior is realized.It comprises two part compositions, and label 11 is a band gap reference, is used to produce a reference voltage, and it is the circuit of a zero-temperature coefficient.That is to say that the reference voltage of its output and its working temperature are irrelevant.Label 12 is a ring oscillator, and the control utmost point of this ring oscillator links to each other with the output of band gap reference 11, is used to receive the reference voltage of band gap reference 11, as its control voltage.The frequency of oscillation of ring oscillator 12 is subjected to the control of this control voltage.But because ring oscillator 12 itself generally has negative temperature coefficient, and the deviation of the integrated technique of ring oscillator itself also can cause the variation of output frequency.Finally cause traditional reference frequency source under different temperature, the chip produced of different batches, its reference frequency changes greatly.The chip environmental condition when reality is used that comprises this reference frequency source is relatively harsher, perhaps causes rate of finished products obviously to reduce.And band gap reference will be used the parasitic-PNP transistor in the CMOS technology, causes area and power consumption to increase.

Summary of the invention

Based on above-mentioned background technology, the object of the present invention is to provide a kind of IF-FRE a reference source with temperature-compensating.

For achieving the above object, IF-FRE a reference source provided by the invention comprises:

Reference voltage source is used for output reference voltage, and it has positive temperature coefficient;

Ring oscillator links to each other with described reference voltage source, receives the reference voltage of described reference voltage source output, produces oscillator signal, and described ring oscillator has negative temperature coefficient;

Described reference voltage source comprises a current source circuit and a biasing circuit;

Described current source circuit comprises four metal-oxide-semiconductors and a resistor; In described four metal-oxide-semiconductors wherein two be the PMOS pipe, manage for NMOS for two in addition; The grid of described two PMOS pipes links to each other; The grid of described two NMOS pipes links to each other; The drain electrode of a NMOS pipe among the drain electrode of a PMOS pipe in described two PMOS pipes and described two NMOS links to each other, and the drain electrode of another NMOS pipe in the drain electrode of another PMOS pipe in described two PMOS pipes and described two the NMOS pipes links to each other; The source electrode of described two PMOS pipes links to each other with power supply Vdd, the source ground of a NMOS pipe in described two NMOS pipes; The source electrode of another NMOS pipe among described two NMOS is by a resistance-grounded system.

In aforesaid IF-FRE a reference source, described biasing circuit comprises two PMOS pipes (P42 and P43); The drain electrode of described two PMOS pipes (P42 and P43) links to each other, and this tie point is exported as reference voltage signal.

Description of drawings

Describe embodiments of the invention in detail below in conjunction with accompanying drawing, above and other objects of the present invention, feature and advantage will be able to further embodiment by the following examples.In the accompanying drawing:

Fig. 1 is the block diagram in traditional frequency reference source;

Fig. 2 is the block diagram in frequency reference of the present invention source;

Fig. 3 is the circuit diagram of ring oscillator in the frequency reference of the present invention source shown in Figure 2;

Fig. 4 is the circuit diagram of reference voltage source in the frequency reference of the present invention source shown in Figure 2.

Embodiment

As shown in Figure 2, IF-FRE a reference source of the present invention is similar at composition to traditional frequency reference source, comprises a reference voltage source 21 and ring oscillator 22.Difference between the two is that reference voltage source 21 of the present invention is the voltage sources with positive temperature coefficient, that is to say, and the reference voltage of its output and temperature relation in direct ratio, that is, working temperature raises, and the reference voltage of its output also raises; Working temperature reduces, and the reference voltage of its output also reduces.

Because as previously mentioned, ring oscillator 22 generally all has negative temperature coefficient, and therefore, the reference voltage source 21 of employing positive temperature coefficient just in time can compensate the negative temperature coefficient feature of ring oscillator 22.That is to say that when the working temperature of chip raise, ring oscillator 22 was owing to its negative temperature coefficient feature, the frequency of the signal source of its output will reduce; At this moment, because reference voltage source 21 has the positive temperature coefficient feature, the reference voltage of its output will improve with the rising of temperature.Thereby make the frequency of the signal source of ring oscillator 22 outputs improve the frequency change that compensation produces owing to variations in temperature.

Fig. 3 shows the circuit diagram of ring oscillator in the frequency reference of the present invention source shown in Figure 2.As shown in Figure 3, the five rank ring oscillators formed by five inverters of this ring oscillator.Wherein PMOS pipe P60 and NMOS pipe N60 constitute first inverter; PMOS pipe P61 and NMOS pipe N61 constitute second inverter; PMOS pipe P62 and NMOS pipe N62 constitute the 3rd inverter; PMOS pipe P63 and NMOS pipe N60 constitute the 4th inverter; PMOS pipe P64 and NMOS pipe N64 constitute the 5th inverter.Serial connection constitutes an annular link between each inverter.Between the serial connection point and earth point of each inverter, connect a NMOS capacitor nc0-nc4.The Vosc point input of the reference voltage that reference voltage source 21 provides from figure is as the control voltage of ring oscillator.The frequency of oscillation of ring oscillator is subjected to the control of this control voltage.

Because the operating frequency of inverter has negative temperature coefficient, the ring oscillator that is made of inverter also just has negative temperature coefficient.Promptly when temperature reduced, frequency raise; When temperature raise, frequency reduced.Simultaneously, the frequency of oscillation of this circuit is subjected to the influence of the influence of pmos greater than nmos under the situation of technological parameter deviation.Promptly when pmos was in fast model, frequency of oscillation was accelerated; When pmos was in slow model, frequency of oscillation slowed down.

Fig. 4 shows the circuit diagram of reference voltage source in the frequency reference of the present invention source shown in Figure 2.As shown in Figure 4, this reference voltage source is made up of two parts: current source circuit and biasing circuit.Current source circuit is that four metal-oxide-semiconductors and a resistor R 40 constitute.In four metal-oxide-semiconductors wherein two be PMOS pipe P40 and P41, manage N40 and N41 for NMOS for two in addition.The grid of two PMOS pipe P40 and P41 links to each other; The grid of two NMOS pipe N40 and N41 links to each other.The drain electrode of a PMOS pipe P40 links to each other with the drain electrode of a NMOS pipe N40, and the drain electrode of another PMOS pipe P41 links to each other with the drain electrode of another NMOS pipe N41; The source electrode of two PMOS pipe P40 and P41 links to each other with power supply Vdd, and a NMOS manages the source ground of N40; The source electrode of another NMOS pipe N41 is by resistor R 40 ground connection.

The characteristics of the current source circuit of this structure are that the b2 voltage of ordering is less with the influence of supply voltage Vdd.When temperature rose, operating current reduced simultaneously, and the b2 point voltage is increased, and promptly the b2 voltage of ordering has positive temperature coefficient.But the problem that this structure exists is when integrated technique changes, and the voltage that b2 is ordered is subjected to the influence of nmos very big.

For addressing this problem, reference voltage source of the present invention adds the one-level biasing circuit again.It is made up of two PMOS pipe P42 and P43.The drain electrode of two PMOS pipe P42 and P43 links to each other, and this tie point is exported as reference voltage signal.This biasing circuit utilizes PMOS pipe P42 to make constant-current source, according to size of devices in proportion replication stream pass over positive temperature coefficient through the electric current of PMOS pipe P41 and NMOS pipe N41, PMOS pipe P43 presses the diode connection, be similar to a resistance here, reference voltage is provided.Resistance reduces when pmos is in fast model, and reference voltage is reduced, and resistance increases during slow model, and reference voltage is risen.Like this, ring oscillator is powered, can carry out temperature-compensating and technological compensa tion, make the stable frequency of ring oscillator output with this reference voltage.

The present invention compares with traditional frequency reference source, has following features:

1. the frequency stability height does not change with temperature, supply voltage, process deviation substantially;

2. yield rate height, range of application is wide;

3. area is little. Traditional band gap reference will be used bipolar device, under same process conditions, MOS technology area of the present invention is smaller;

4. low in energy consumption, owing to entirely realize that with cmos circuit operating current can be done littlelyr.

Claims

1, a kind of IF-FRE a reference source comprises:

Ring oscillator links to each other with described reference voltage source, receives the reference voltage of described reference voltage source output, produces oscillator signal, and described ring oscillator has negative temperature coefficient; Described reference voltage source comprises a current source circuit and a biasing circuit;

Described current source circuit comprises four metal-oxide-semiconductors and a resistor (R40); In described four metal-oxide-semiconductors wherein two be PMOS pipe (P40 and P41), manage (N40 and N41) for NMOS for two in addition; The grid of described two PMOS pipes (P40 and P41) links to each other; The grid of described two NMOS pipes (N40 and N41) links to each other; The drain electrode of the NMOS pipe (N40) among the drain electrode of PMOS pipe (P40) in described two PMOS pipes and described two NMOS links to each other, and another PMOS in described two PMOS pipes manages the drain electrode of (P41) and links to each other with the drain electrode that another NMOS in described two NMOS pipes manages (N41); The source electrode of described two PMOS pipes (P40 and P41) links to each other with power supply Vdd, the source ground of the NMOS pipe (N40) in described two NMOS pipes; The source electrode of another NMOS pipe (N41) among described two NMOS is by a resistor (R40) ground connection.

2. IF-FRE a reference source as claimed in claim 1 is characterized in that, described biasing circuit comprises two PMOS pipes (P42 and P43); The drain electrode of described two PMOS pipes (P42 and P43) links to each other, and this tie point is exported as reference voltage signal.