CN104218915A - Low-energy-consumption and quick-oscillation-starting crystal oscillator circuit with automatic detection function - Google Patents

Abstract

The invention discloses a low-energy-consumption and quick-oscillation-starting crystal oscillator circuit with an automatic detection function. The crystal oscillator circuit is mainly characterized in that at the initial starting stage of a crystal oscillator, bias is provided for an inverting amplifier by double current sources simultaneously, and large current can guarantee that the inverting amplifier provides high gain when the crystal oscillator circuit is in oscillation starting, so that quick oscillation starting is achieved; an inverse shaping chain mainly comprises a class-AB amplifier, so that faint signals can be captured quickly during oscillation starting and a crystal oscillator clock is generated by means of amplification; the generated crystal oscillator clock can trigger D flip-flops to switch off one of the double current sources, so that operation of the crystal oscillator in a low power consumption mode after oscillation starting is guaranteed, and the contradiction between oscillation starting time and power consumption is solved effectively.

Description

A kind of low-power consumption, fast start-up crystal oscillating circuit with automatic detection function

Technical field

The present invention is used for integrated circuit (IC) design field, relates to a kind of crystal oscillator, is specifically related to a kind of low-power consumption, the fast start-up crystal oscillating circuit with automatic detection function.

Background technology

Quartz oscillator is a kind of resonating device utilizing the piezoelectric effect of quartz crystal to make, because quartz crystal has very high quality factor, therefore quartz oscillator can produce the accurate and stable waveform of frequency, is widely used in and requires the higher field such as clock and watch, military project, communication to frequency of oscillation.

Along with the high speed development of portable set in the communications field in recent years, the design requirement of the integrated circuit of low power consumption and low cost is become increasingly conspicuous.In the multinomial design objective of crystal oscillating circuit, Induction Peried is particularly important, particularly ask for something Quick completes initialize integrated circuit for clock, circuit designers adopts the method improving inverting amplifier bias current to make input mutual conductance pipe obtain larger mutual conductance and then to improve the gain of inverting amplifier usually, accelerate the Induction Peried of crystal oscillating circuit, but this to be the mode of sacrificing power consumption exchange Induction Peried for, the contradiction between Induction Peried and low power dissipation design can not be solved.In this respect, the patent " low-power consumption of adjustment starting condition for oscillation able to programme, fast start-up crystal oscillator module " of being applied for by Hangzhou Zhongke Microelectronic Co., Ltd. have employed the outstanding contradiction solved between power consumption and Induction Peried of the method for automatic gain control loop, the present invention achieves a kind of low-power consumption, the fast start-up crystal oscillating circuit with automatic detection function equally from different angles, while completing crystal oscillator fast start-up, complete the realization of low-power consumption more fast.

Summary of the invention

The present invention be directed to contradiction between Induction Peried and low-power consumption in the design of traditional crystal oscillating circuit, propose there is automatic detection function low-power consumption, fast start-up crystal oscillating circuit, the present invention is characterized in:

Described circuit comprises the d type flip flop being provided the inverting amplifier of electric current, feedback resistance (Rf), reshaper chain, n series connection by double-current source of Embedded, and external without source crystal (XTAL), load capacitance network first electric capacity (C1) and the second electric capacity (C2);

In sheet, the grid end of the mutual conductance pipe NMOS tube (N1) of inverting amplifier connects the external output without source crystal (XTAL) (XTALI), connect one end of the first electric capacity (C1) simultaneously, the other end ground connection of the first electric capacity (C1), the grid end of NMOS tube (N1) is also connected to one end of feedback resistance (Rf), the source ground connection of NMOS tube (N1), the drain terminal of NMOS tube (N1) connects external another output (XTALO) without source crystal (XTAL), be connected to one end of the second electric capacity (C2) simultaneously, the other end ground connection of the second electric capacity (C2), the drain terminal of NMOS tube (N1) is also connected to the other end and the first load current source (I of feedback resistance (Rf) _b1) one end and the second load current source (I _b2) one end, the first load current source (I _b1) and the second load current source (I _b2) the other end all receive power supply (VDD), the drain terminal of NMOS tube (N1) is connected to again the input (IN) of reshaper chain, the output (OUT) of reshaper chain receives output terminal of clock mouth (CLK), receive the input (CK) of n flip-flops in series simultaneously, the data input pin (D) of the first d type flip flop (D1) connects input port (Z1), the data output end (Q) of the first d type flip flop (D1) connects the data input pin (D) of the second d type flip flop (D2), by that analogy, until the n-th d type flip flop, the data output end (Q) of the n-th d type flip flop, be used for control second load current source (I _b2) the opening and shutting off of electric current, the reset terminal (RN) of this n d type flip flop is all connected to input (Z2).

Main feature of the present invention is:

1. the inverting amplifier in crystal oscillating circuit provides biased jointly by double-current source, wherein a road current source is controlled, to ensure that crystal oscillating circuit is operated in big current pattern, after starting of oscillation when starting of oscillation, one of them controllable current source turns off, under making crystal oscillator be operated in low-power consumption mode;

2. add the d type flip flop of n series connection, d type flip flop completes of short duration reset in the starting stage that powers on, the output that resets controls controllable current source and is in conducting state, after crystal oscillating circuit has clock generating, data can be sent to controllable current source by d type flip flop, turned off by controllable current source, the object adopting multiple d type flip flop to connect prevents the pulse signal of external interference from changing flip-flop states;

3. reshaper chain mainly have employed the amplifier of an AB class, crystal oscillator oscillator signal is coupled to the input of amplifier by capacitance, and amplifier biasing is provided by independent bias voltage, weak oscillation signal during such crystal oscillator starting of oscillation can be amplified rapidly by class ab ammplifier and produce clock.

Accompanying drawing explanation

A kind of low-power consumption, fast start-up crystal oscillating circuit structural representation with automatic detection function that Fig. 1 the present invention proposes;

Fig. 2 reshaper chain circuit structural representation.

Embodiment

Below in conjunction with accompanying drawing, describe a kind of of disclosure of the invention in detail and there is the low-power consumption of automatic detection function, the implementation process of fast start-up crystal oscillating circuit.

In an embodiment of the present invention, as shown in Figure 1, circuit comprises the d type flip flop being provided the inverting amplifier of electric current, feedback resistance Rf, reshaper chain, n series connection by double-current source of Embedded, and external without source crystal XTAL, load capacitance network first electric capacity C1 and the second electric capacity C2.

In sheet, the NMOS tube N1 of inverting amplifier provides mutual conductance for amplifier, its effect is equivalent to a negative resistance, the grid end of NMOS tube N1 connects the external output XTALI without source crystal XTAL, connect one end of the first electric capacity C1 simultaneously, the other end ground connection of the first electric capacity C1, the grid end of NMOS tube N1 is also connected to one end of feedback resistance Rf, the effect of feedback resistance Rf is for the grid end of NMOS tube N1 provides direct current biasing, the source ground connection of NMOS tube N1, the drain terminal of NMOS tube N1 connects external another output XTALO without source crystal XTAL, be connected to one end of the second electric capacity C2 simultaneously, the other end ground connection of the second electric capacity C2, the drain terminal of NMOS tube N1 is also connected to the other end and the first load current source I of feedback resistance Rf _b1one end and the second load current source I _b2one end, the first load current source I _b1with the second load current source I _b2the other end all receive power vd D, the drain terminal of NMOS tube N1 is connected to again the input IN of reshaper chain, the output OUT of reshaper chain receives output terminal of clock mouth CLK, receive the input CK of n flip-flops in series simultaneously, the data input pin D of the first d type flip flop D1 connects input port Z1, the data output end Q of the first d type flip flop D1 connects the data input pin D of the second d type flip flop D2, by that analogy, until the n-th d type flip flop Dn, the data output end Q of the n-th d type flip flop Dn, is used for control second load current source I _b2opening and shutting off of electric current, the reset terminal RN of this n d type flip flop is all connected to input Z2.

After crystal oscillator powers on, reseting controling end Z2 has a reset operation fast, suppose that Z2 is that low level resets effectively, like this so d type flip flop all can be reset, the operation that input Z2 completes trigger reset becomes high level afterwards at once, so the reset terminal of trigger is not enable, trigger is in normal mode of operation, but be supplied to trigger owing to now not having clock, so the State-output when output of each trigger remains reset, supposing to reset, to export data be low level, then suppose the second current source I of being controlled by the n-th d type flip flop _b2be in conducting state, so crystal oscillating circuit powers on completing, and after reset initialization is completed to all d type flip flops, simultaneously inverting amplifier provides bias current by two current sources, the benefit done like this is, the mutual conductance of input pipe can be promoted, improve the gain of amplifier, make the starting of oscillation of crystal oscillating circuit fast and stable.Certainly, in design circuit process, even if at the second current source I _b2turn off and only have the first current source I _b1when bias current is provided, also to guarantee that crystal oscillating circuit can normally starting of oscillation, adopt double-current source to provide biased primary and foremost purpose to improve gain exactly here, accelerate Induction Peried.

When after crystal oscillator starting of oscillation, oscillator signal export through reshaper chain circuit, the basic circuit structure of shaping circuit as shown in Figure 2, current source I _bby PMOS P1, the mirror image effect of PMOS P2 and NMOS tube N2, be mirrored to the grid end of the class ab ammplifier be made up of PMOS P3 and NMOS tube N3, by reasonably arranging bias current size, the DC current gain of amplifier can be operated in a considerable state, crystal oscillator oscillator signal receives the input IN of reshaper, and the grid end of PMOS P3 is coupled to by the 3rd electric capacity C3, also be coupled to the grid end of NMOS tube N3 by the 4th electric capacity C4 simultaneously, amplifier out connects the input of inverter INV, the output port OUT of the output termination reshaper chain of inverter INV.The sinusoidal signal of vibration is input to the input of class ab ammplifier through capacitance, the benefit done like this is, first the DC operation state that every straight effect can not have influence on amplifier of direct voltage in the vibration starting stage due to electric capacity of the oscillator signal of crystal oscillator output, and the external world provides bias voltage that amplifier operation can be made a best DC current gain state for amplifier, starting stage faint oscillator signal can be caught and amplify rapidly and promote rear class inverter and produce clock and export, this is more simple than tradition faster through a series of inverter shaping, if make inverter overturn because oscillator signal exports, must the amplitude of oscillation of oscillator signal enough large, as everyone knows, the starting of oscillation amplification process of crystal oscillator is very slow, need the iteration in cycle many times, can be amplified to and promote inverter upset.Therefore, by this capacitive coupling and the secondary mode of amplifying can more quick obtaining crystal oscillator clock complete follow-up operation.

In crystal oscillator starting of oscillation and after producing clock, clock can be sent to the input end of clock CK of d type flip flop, input Z1 is a high level, when the rising edge of first clock cycle arrives the first trigger D1, the high level of input Z1 can be transferred to the data output end Q of the first trigger D1, the input D of such second d type flip flop D2 becomes high level, when the rising edge of second clock cycle arrives the second trigger D2, the high level of the input D of the second d type flip flop D2 can be transferred to the data output end Q of the second d type flip flop D2, by that analogy, when the rising edge of the n-th clock cycle passes to the n-th d type flip flop, the data output end Q of the n-th d type flip flop becomes high level, and then control the second current source I _b2turn off, make crystal oscillating circuit only by the first current source I _b1current offset is provided to work on.Here the value of " n " can get 3 ~ 5 for best, and can certainly select flexibly according to the actual requirements, the main purpose done like this prevents trigger clock end from producing misoperation because of spurious pulse to trigger, controls the second current source I more accurately _b2conducting and shutoff.

Crystal oscillating circuit is after the starting stage that powers on has controlled fast start-up by double-current source, within the time in n cycle producing clock, control to automatically shut down a wherein road current source by register, complete the operation of low-power consumption rapidly, under making crystal oscillator be operated in a more stable low current condition, while contributing to improving crystal oscillator useful life, efficiently solve the contradiction between Induction Peried and power consumption in crystal oscillating circuit design.

Claims (1)

1. one kind has low-power consumption, the fast start-up crystal oscillating circuit of automatic detection function, it is characterized in that, described circuit comprises the d type flip flop being provided the inverting amplifier of electric current, feedback resistance (Rf), reshaper chain, n series connection by double-current source of Embedded, and external without source crystal (XTAL), load capacitance network first electric capacity (C1) and the second electric capacity (C2);

In sheet, the grid end of the mutual conductance pipe NMOS tube (N1) of inverting amplifier connects the external output without source crystal (XTAL) (XTALI), connect one end of the first electric capacity (C1) simultaneously, the other end ground connection of the first electric capacity (C1), the grid end of NMOS tube (N1) is also connected to one end of feedback resistance (Rf), the source ground connection of NMOS tube (N1), the drain terminal of NMOS tube (N1) connects external another output (XTALO) without source crystal (XTAL), be connected to one end of the second electric capacity (C2) simultaneously, the other end ground connection of the second electric capacity (C2), the drain terminal of NMOS tube (N1) is also connected to the other end and the first load current source (I of feedback resistance (Rf) _b1) one end and the second load current source (I _b2) one end, the first load current source (I _b1) and the second load current source (I _b2) the other end all receive power supply (VDD), the drain terminal of NMOS tube (N1) is connected to again the input (IN) of reshaper chain, the output (OUT) of reshaper chain receives output terminal of clock mouth (CLK), receive the input (CK) of n flip-flops in series simultaneously, the data input pin (D) of the first d type flip flop (D1) connects input port (Z1), the data output end (Q) of the first d type flip flop (D1) connects the data input pin (D) of the second d type flip flop (D2), by that analogy, until the n-th d type flip flop, the data output end (Q) of the n-th d type flip flop, be used for control second load current source (I _b2) the opening and shutting off of electric current, the reset terminal (RN) of this n d type flip flop is all connected to input (Z2).