CN2167485Y - Infrared monolithic wireless ear phone - Google Patents

Abstract

The utility model relates to an infrared monolithic wireless ear phone, which is composed of a special infrared speech signal processing IC and peripheral elements. The infrared monolithic wireless ear phone comprises a band pass filter, an intermediate amplifier stage, a phase-locked loop, a deemphasis circuit, a volume potentiometer, an audio power amplifier stage and an ear phone. The utility model has the advantages of receiver circuit integration, small volume, light weight, little power consumption, small quiescent current, good property, high reliability and low production cost.

Description

Infrared monolithic wireless ear phone

The utility model is relevant with infrared voice signal transmission system, and is especially relevant with the wireless headset that utilizes infrared voice signal processing application-specific integrated circuit (ASIC).

Traditional Infrared wireless earphone is a kind of new small-sized household electroacoustic equipment that occurs in the later stage eighties, and it is with wireless, no wave interference, and high tone quality and getting consumer reception is suitable as television set, the electro-acoustic conversion device of radio-cassette player or other stereo set.Because the infrared tube cut-off frequency is 1MH2, and the low more infrared emission efficient of carrier frequency is high more.So be typically chosen in the frequency low side.Television audio signal maximum frequency deviation is ± 50KH, maximum modulating frequency 15KH, and the width of frequency-modulated wave is 130KH2, frequency band is very wide, only in this way could improve anti-jamming capacity, and good acoustical quality is arranged.Such radiating circuit is still realized easily, and receiving circuit must solve low carrier frequency, wide band demodulation problem, addressing this problem the unique method that also will be beneficial to system integration simultaneously is to use PHASE-LOCKED LOOP PLL TECHNIQUE, other existing FM broadcast receiver chip all can not address this problem.Existing Infrared wireless earphone all is to adopt universal integrated circuit to make, perhaps adopt PLL as the FM demodulator of PM signal PM, audio frequency amplifies employing universal audio power discharging integrated block, perhaps adopting the LC loop is the FM signal method realization FM signal demodulation of demodulation again with the FM conversion of signals, and audio frequency power amplifier adopts the universal audio amplification circuit.Because the both adopts standard production of integrated circuits earphone, power consumption is big, and static working current can be up to 12mA, and battery is extremely short useful life.Though the latter as FM frequency modulation, owing to use LC loop peak value to pick up ripple, has reduced the anti-interference of earphone with the 3V power supply relatively.

The purpose of this utility model provides a kind of reliability height, and antijamming capability is strong, and acoustical quality is good, low-voltage, and low-power consumption, quiescent current is little, and volume is little, and is in light weight, earphone, receiver is integrated, the monolithic Infrared wireless earphone that production cost is low.

The utility model is achieved in that

The utility model is made of application-specific integrated circuit (ASIC) UE701 and peripheral cell thereof, UE701 by in put level, phase-locked loop, audio frequency power amplifier level and power circuit and constitute.In put level by band pass filter, the intermediate level circuit that multistage constant-current source differential amplifier is formed and provide the squelch circuit of squelch switch signal and peripheral cell thereof to constitute, in put level the FM signal filtering of input amplified, and produce the signal of control squelch switch.

A FM signal of putting the level amplification in the warp is delivered to phase-locked link demodulation.Phase-locked loop is by voltage controlled oscillator (VCO), and two balances are touched like multiplier, and direct current amplifier and low pass filter are formed.Multiplier is as phase discriminator, produce the phase error voltage signal, the voltage controlled oscillator output signal frequency is drawn close to frequency input signal, phase difference reduces between two signals, low pass filter is by linear resistance, the linear circuit that electric capacity constitutes, direct current amplifier improves loop gain, makes that FM signal is relative with the phase error of VCO output signal to be reduced.

Audio signal after the demodulation is delivered to deaccentuator, the signal of preemphasis reduction when making emission.

Noise when regulating volume in order to improve adopts two balance shunting gain control circuits as the electronic sound volume regulating circuit,

The last warp let-off audio frequency power amplifier of audio signal level is carried out audio voltage amplification and audio power and is amplified, and promotes earphone work.

Power circuit provides stabilized voltage power supply, and base bias is provided, and stablizes quiescent point.

Infrared receiving tube D of the present utility model receives infrared FM signal, delivers to band pass filter in the chip through capacitor C 6 from 16 pin of UE701, puts level then greatly in UE701.In put the level establish internal feedback circuitry, internal bias feeds back to input stage by output stage by the emitter follower level displacement circuit, is fed back to the direct current unity feedback, has the effect of stable operating point.Capacitor C 12 is connected to internal feedback circuitry, in order to the purification direct current, and in the peripheral circuit of amplifying stage, capacitor C 6, C7, C12 connect 16 pin of UE701 respectively, 15 pin, 1 pin influences the common scope of amplifier, resistance R 7, R1,6 pairs of input signals of capacitor C carry out bandpass filtering.R7 connects C6 and ground connection, and R1 connects 16 pin and 15 pin of UE701.The one-level level displacement circuit of putting level in the FM signal warp after the amplification is connected to 14 pin, and by resistance R 4, the R6 dividing potential drop is provided in providing by a grade level displacement circuit working point.Capacitor C 5 filtering noises, capacitor C 1,6,2,9 pin that C2, C14 meet UE701 respectively play the filter effect of making an uproar.

Put the phase-locked loop that grade level displacement circuit is delivered to UE701 in the frequency modulation amplifying signal warp, exchange frequency demodulated signal.Voltage controlled oscillator (VCO) is an integration--Schmidt's voltage controlled oscillator.R8 is used to regulate the frequency of oscillation of VCO, connects 11 pin of UE701.C11, C10 connect 13 pin respectively, and 12 pin play filtering noise.

Audio signal is delivered to the audio frequency power amplifier level of UE701 at last, promotes earphone S.S connects 3 pin and 7 pin.Peripheral cell R2, R3, C8, C9 constitutes feedback loop.R2, R3 connect 5 pin respectively, 6 pin.The effect of feedback loop is the DC level of regulating output automatically, make it be stabilized in the midpoint potential of power supply, and to the negative feedback of AC signal generation Voltage Series, improve the performance of entire circuit, C3 is connected to 7 pin, being equivalent to provides equivalent source at the signal negative half period to the OTL circuit of audio frequency power amplifier level, and makes the usefulness of audio signal coupling.

The peripheral cell C4 that links to each other with external power supply Vcc.R5 connects 3 pin, and 2 pin play filtering decoupling effect.

The utility model utilizes the advantage and the characteristics of integrated circuit as far as possible, makes earphone, and Monolithic Receivers is integrated.Increased the function of system, compared with the earphone that existing device is made, the utility model has increased inner source of stable pressure, and the chip voltage scope of application is wide, is 2.6-10V.A large amount of constant-current sources that use are made micropower circuit, and the chip quiescent current is 2.8-4mA.Increase squelch circuit, reduced noise, improved signal to noise ratio.The DC electronic attenuator is used in volume control, has eliminated potentiometer and has regulated the influence of contact noise to tonequality.In application-specific integrated circuit (ASIC), adopt phase-locked loop circuit demodulation FM signal, solved low carrier frequency, the FM signal demodulation problem of broadband modulation.Peripheral cell is few, and the reliability height is produced and adjusted and reduced conveniently, and is with low cost.

Fig. 1 is the internal frame diagram of the utility model UE701 application-specific integrated circuit (ASIC).

Fig. 2 is circuit theory diagrams of the present utility model.

Claims (2)

1, the monolithic Infrared wireless earphone, receive the infrared light FM signal of infrared audio signal transmitter emission by infrared receiving tube, and the infrared light FM signal is converted to the electric current that changes with infrared light intensity, issuable low-frequency voltage signal of filter elimination ordinary ray and noise, in carrying out, amplifier puts, in FM signal after putting after demodulation, enter volume control and power amplifier provides sound output to loud speaker, put level in it is characterized in that, phase-locked loop, audio frequency power amplifier level and power circuit are formed UE701 (ASIC), in put level by the logical filter of band filter, the intermediate level circuit that multistage constant-current source differential amplifier stage is formed constitutes with squelch circuit that the squelch switch signal is provided and peripheral cell thereof, in put level the FM signal filtering of input amplified, and the signal of generation control squelch switch

A FM signal of putting the level amplification in the warp is delivered to phase-locked link demodulation, phase-locked loop is by voltage controlled oscillator (VCO), two balance simulation multiplier, direct current amplifier and low pass filter are formed, multiplier is as phase discriminator, produce the phase error voltage signal, the voltage controlled oscillator output signal frequency is drawn close to frequency input signal, phase difference reduces between two signals, loop low pass filter is by linear resistance, the linear circuit that electric capacity constitutes, direct current amplifier can improve loop gain, makes that FM signal is relative with the phase error of VCO output signal to be reduced

Audio signal after the demodulation is delivered to deaccentuator, the signal of preemphasis reduction when making emission,

Noise when regulating volume in order to improve adopts two balance shunting gain control circuits as the electronic sound volume regulating circuit,

Audio signal is sent footpath audio frequency power amplifier level at last, carries out audio voltage amplification and audio power and amplifies, and promotes earphone,

Power circuit provides stabilized voltage power supply, and base bias is provided, and stablizes quiescent point.

2, monolithic Infrared wireless earphone according to claim 1 is characterized in that receiving infrared FM signal by infrared receiving tube D, delivers to band pass filter in the sheet through capacitor C 6 from 16 pin of UE701, in UE701, put level then and amplify, in put level and establish internal feedback circuitry, internal bias feeds back to input stage by output stage by the emitter follower level displacement circuit, be fed back to the direct current unity feedback, have the effect of stable operating point, capacitor C 12 is connected to internal feedback circuitry, in order to the purification direct current, in the peripheral circuit of amplifying stage, capacitor C 6, C7, C12 connect 16 pin of UE701,15 pin respectively, 1 pin, influence the free transmission range of amplifier, resistance R 7, C6, R1 carries out bandpass filtering to input signal, R7 is connected to C6 and ground connection, and R1 is connected to 16 pin and 15 pin of UE701, puts the one-level level displacement circuit of level in the FM signal warp after the amplification, be connected to 14 pin, by resistance R 4, the R6 dividing potential drop is provided in providing by a grade level displacement circuit working point, capacitor C 5 filtering noises, C1, C2, C14 connects 6,2,9 pin play the filter effect of making an uproar.

Put the phase-locked loop that grade level displacement circuit is delivered to UE701 in the frequency modulation amplifying signal warp, exchange frequency demodulated signal.Voltage controlled oscillator (VCO) is integration one Schmidt's voltage controlled oscillator, and R8 is used to regulate the frequency of oscillation of VCO, connects 11 pin of UE701, and C11, C10 connect 13 pin respectively, and 12 pin play filtering noise.

Audio signal after the demodulation is delivered to the electronic sound volume regulating circuit of UE701,

Potentiometer W connects 10 pin of UE701, regulates and listens to volume, and capacitor C 13 connects 9 pin and removes noise,

Audio signal is delivered to the audio frequency power amplifier level of UE701 at last, promotes earphone S, and S connects 3 pin and 7 pin, peripheral cell R2, R3, C8, C9 constitutes feedback loop, R2, R3 connect 5 pin respectively, 6 pin, the effect of feedback loop is the DC level of regulating output automatically, make its midpoint potential that is stabilized in power supply, and AC signal is produced the Voltage Series negative feedback, improve the performance of entire circuit.C3 is connected to 7 pin, and being equivalent to provides equivalent source at the signal negative half period to the DTL circuit of audio frequency power amplifier level, and makes the usefulness of audio signal coupling,

The peripheral cell C4 that links to each other with external power supply Vcc, R5 play filtering decoupling effect.