CN101951223A

CN101951223A - Low-power consumption oscillator circuit

Info

Publication number: CN101951223A
Application number: CN 201010503179
Authority: CN
Inventors: 赵鹤鸣; 李富华; 王汉祥; 谢卫国; 黄秋萍; 江石根
Original assignee: SUZHOU HUAXIN MICRO-ELECTRONICS CO LTD; Suzhou University
Current assignee: SUZHOU HUAXIN MICRO-ELECTRONICS CO LTD; Suzhou University
Priority date: 2010-10-12
Filing date: 2010-10-12
Publication date: 2011-01-19

Abstract

The invention discloses a low-power consumption oscillator circuit which comprises a detection part and a shaping control part, wherein the detection part has two reference voltages, and the shaping control section comprises a shaping circuit, a capacitor, a charge constant current source and a discharge constant current source. The low-power consumption oscillator circuit is characterized in that an electronic switch is connected in series in the return circuit of the discharge constant current source; the detection part is provided with a comparator and a gating switch, one end of the gating switch is connected with the in-phase end of the comparator, the waveform output end of the capacitor is connected with the out-phase end of the comparator, and the output end of the comparator is connected to the input end of the shaping circuit; the electronic switch and the gating switch are under the synchronization control of the output end of the shaping circuit, the gating switch switches on the lower reference voltage when the electronic switch is switched on, and the gating switch switches on the higher reference voltage when the electronic switch is switched off; and the current value of the capacitor discharge constant current source is higher than that of the capacitor charge constant current source. By multiplexing the comparator, the invention simplifies the circuit and lowers the power consumption of the oscillator.

Description

A kind of low-power consumption pierce circuit

Technical field

The present invention relates to a kind of pierce circuit, particularly a kind of pierce circuit that is suitable for the integrated circuit use of low-power consumption.

Background technology

Oscillator is the important component part of many electronic systems, has been widely used in such as in the mobile communication equipments such as PHS (personal handyphone system), WLAN (local area network (LAN)) and transceiver; The periodic signal that also usually needs some low frequencies in the analog integrated circuit such as clock signal, has the pulse signal of certain duty ratio etc.Wherein, the RC oscillator is the oscillator that arrives commonly used in the CMOS technology because its structure is simple relatively, and peripheral cell is few.

Traditional RC oscillator equivalent-simplification figure as shown in Figure 1, it is made up of two parts, a part is the test section, another part is the shaping control section.The test section is made up of two reference voltages (VH, VL) and two comparators, detects constant-current source to electric capacity charging upper voltage limit and discharge lower voltage limit; Two constant-current source (I of shaping unit control ₁, I ₂) moving in circles to capacitor charge and discharge.

Along with the develop rapidly of portable electronic product, the low-power consumption of electronic product becomes the focus of concern.Need to be provided with two comparators in traditional RC oscillator as shown in Figure 1, circuit structure is relatively complicated, and power consumption is higher, has further improved necessity.

Summary of the invention

The present invention seeks to provides a kind of pierce circuit of low-power consumption, to be suitable for the demand of integrated circuit small size, low-power consumption by simplifying circuit structure.

For achieving the above object, the technical solution used in the present invention is: a kind of low-power consumption pierce circuit, comprise test section and shaping control section, described test section has two reference voltages, described shaping control section comprises shaping circuit, electric capacity, to the constant-current source of electric capacity charging with to the constant-current source of capacitor discharge, in the constant-current source loop of described shaping control section, be in series with electronic switch to capacitor discharge; Described test section is provided with a comparator and a gating switch, and gating switch one end connects the in-phase end of comparator, and the waveform output of electric capacity is connected to the end of oppisite phase of comparator, and the output of comparator is connected to the input of shaping circuit; Described electronic switch and gating switch are by the output Synchronization Control of shaping circuit, and when electronic switch closes, gating switch is communicated with low reference voltage, and when electronic switch disconnected, gating switch was communicated with high reference voltage; To the current value of the constant-current source of capacitor discharge greater than current value to the constant-current source of electric capacity charging.

Operation principle of the present invention is, shown in accompanying drawing 2, if initial voltage is a high level on the capacitor C, gating switch S1 selects low reference voltage VL, the closed conducting of electronic switch S2, since to the current value of the constant-current source I2 of capacitor discharge greater than current value to the constant-current source I1 of electric capacity charging, the capacitor C discharge, voltage linear reduces on the capacitor C, when voltage is lower than VL on the electric capacity, the upset of comparator output level, gating switch S1 selects high reference voltage VH, and electronic switch S2 disconnects, and capacitor C begins charging, electric capacity powers on and presses off the initial line increase, relatively output level upset when voltage is higher than VH on the capacitor C, gating switch S1 selects low reference voltage VL, the closed conducting of electronic switch S2, capacitor discharge, so repeatedly.

Because the technique scheme utilization, the present invention compared with prior art has following advantage:

1. the present invention passes through the multiplexing of a comparator, realizes the function of two comparators of traditional RC oscillator, has simplified circuit, when being applied to integrated circuit, the design layout area is reduced;

2. because the present invention has reduced by a comparator, reduce the power consumption of oscillator, helped the application in portable type electronic product.

Description of drawings

Fig. 1 is traditional RC oscillator equivalent-simplification figure;

Fig. 2 is the structural representation block diagram of oscillator of the present invention;

Fig. 3 is the circuit diagram of the pierce circuit of the embodiment of the invention.

Embodiment

Below in conjunction with drawings and Examples the present invention is further described:

Embodiment one: shown in accompanying drawing 2, a kind of low-power consumption pierce circuit comprises test section and shaping control section, and described test section has two reference voltages, and described shaping control section comprises shaping circuit, capacitor C, to the constant-current source I of electric capacity charging ₁With constant-current source I to capacitor discharge ₂, at the constant-current source loop I of described shaping control section to capacitor discharge ₂In, be in series with electronic switch S ₂Described test section is provided with a comparator and a gating switch S ₁, gating switch S ₁One end connects the in-phase end of comparator, and the waveform output of capacitor C is connected to the end of oppisite phase of comparator, and the output of comparator is connected to the input of shaping circuit; Described electronic switch S ₂With gating switch S ₁By the output Synchronization Control of shaping circuit, as electronic switch S ₂When closed, gating switch S ₁Be communicated with low reference voltage VL, as electronic switch S ₂During disconnection, gating switch S ₁Be communicated with high reference voltage VH; Constant-current source I to capacitor discharge ₂Current value greater than constant-current source I to electric capacity charging ₁Current value.

The physical circuit of present embodiment is referring to shown in the accompanying drawing 3, the left side of Fig. 3 is a comparator, by nmos pass transistor MN1, MN2, MN3 and MN4, PMOS transistor MP1, MP2 and MP3 form, low generating circuit from reference voltage is made up of nmos pass transistor MN5 and PMOS transistor MP11, high generating circuit from reference voltage is by nmos pass transistor MN6 and PMOS transistor MP12, MP13 forms, the shaping control section is by nmos pass transistor MN5, MN7 and inverter INV1 constitute, charging constant-current source I1 is made of PMOS transistor MP8, discharge constant-current source I2 is made of nmos pass transistor MN10, MP9 and MP4, MP5, MP6, MP7, MP8 forms the image current mirror, oscillator enable control circuit by nmos pass transistor MN11, PMOS transistor MP10, inverter INV2 constitutes, and energy-storage travelling wave tube is a capacitor C 1.

Operation principle to oscillator is described in detail below: EN is the Enable Pin of pierce circuit, when EN is logic low, PMOS transistor MP10 conducting, nmos pass transistor MN11 conducting, PMOS transistor MP8 as constant-current source I1 is operated in dark linear zone, nmos pass transistor MN10 as constant-current source I2 turn-offs, and voltage is approximately equal to supply voltage on the electric capacity at this moment.When EN was logic high, PMOS transistor MP10 turn-offed, and nmos pass transistor MN10 turn-offs, charging constant-current source I1 work.The grid of nmos pass transistor MN1 is the in-phase end of secondary comparator, and the grid of nmos pass transistor MN2 is the end of oppisite phase of secondary comparator, and PMOS transistor MP1 and MP2 constitute current mirror, as the load of differential input, realizes that both-end becomes single-ended output.The grid of PMOS transistor MP3 is the partial input of comparator, and nmos pass transistor MN4 is as its active load.Because the approximate supply voltage of in-phase end this moment, comparator is output as logic high, nmos pass transistor MN5 conducting, and the PMOS transistor MP11 that diode connects provides low relatively reference level for the end of oppisite phase of comparator | V _{Gs (MP11)}|, comparator output signal is by nmos pass transistor MN5 simultaneously, nmos pass transistor MN7, inverter INV1 shaping conversion becomes logic low, and switching tube nmos pass transistor MN8 turn-offs, discharge constant-current source I2 work, get I2＞I1, then capacitor C 1 is by nmos pass transistor MN10 discharge, and the discharging current size is I2-I1.Capacitor C 1 is being discharged always, and the voltage linear on the capacitor C 1 reduces, and has only the low reference level that is reduced to end of oppisite phase when voltage | V _{Gs (MP11)}| the time, the comparator output state changes, and becomes logic low.Nmos pass transistor MN5 closes end, and then PMOS transistor MP11 turn-offs, then nmos pass transistor MN6, PMOS transistor MP13 and PMOS transistor MP12 conducting, and for the comparator inverting input provides high relatively reference level, size is | V _{Gs (MN6)}|+| V _{Gs (MP13)}|+| V _{Gs (MP12)}|.Comparator output signal passes through nmos pass transistor MN5, nmos pass transistor MN7, and inverter INV1 shaping conversion becomes logic high, switching tube nmos pass transistor MN8 conducting, constant-current source I2 closes, and constant-current source I1 is capacitor C 1 charging, and the charging current size is I1.Capacitor C 1 is charged always, and voltage linear increases on the capacitor C 1, has only the high reference level that is increased to end of oppisite phase when voltage | V _{Gs (MN6)}|+| V _{Gs (MP13)}|+| V _{Gs (MP12)}| the time, relatively output state changes, and becomes logic high, begins discharge, and said process constantly moves in circles.

Claims

1. a low-power consumption pierce circuit comprises test section and shaping control section, and described test section has two reference voltages, and described shaping control section comprises shaping circuit, electric capacity (C), to the constant-current source (I of electric capacity charging ₁) and to the constant-current source (I of capacitor discharge ₂), it is characterized in that: at the constant-current source loop (I of described shaping control section capacitor discharge ₂) in, be in series with electronic switch (S ₂); Described test section is provided with a comparator and a gating switch (S ₁), gating switch (S ₁) end connects the in-phase end of comparator, the waveform output of electric capacity (C) is connected to the end of oppisite phase of comparator, and the output of comparator is connected to the input of shaping circuit; Described electronic switch (S ₂) and gating switch (S ₁) by the output Synchronization Control of shaping circuit, as electronic switch (S ₂) when closed, gating switch (S ₁) be communicated with low reference voltage (VL), as electronic switch (S ₂) when disconnecting, gating switch (S ₁) the high reference voltage (VH) of connection; Constant-current source (I to capacitor discharge ₂) current value greater than constant-current source (I to electric capacity charging ₁) current value.