CN1061122A - Diode-triode mixture detector - Google Patents

Abstract

At the final stage radio frequency amplifier colelctor electrode that receives the amplitude modulation CF signal and connect two loops and output to power supply V+, loop is by silicon (or germanium) the diode D of NP connection ₁, be connected to radio frequency L ₁C ₂The inductance of the parallel resonance tank circuit, and pass through L ₁C ₂The parallel resonance tank circuit is communicated with V+, and another loop is by silicon (or germanium) triode Q ₂Emitter junction NP, connect R ₄C ₄Parallel circuit is connected V ₊, Q ₂The emitter junction detection is in lightly conducting state, Q ₂Emitter stage R ₄C ₄Output low frequency rectified signal in parallel, Q ₂Colelctor electrode R ₅C ₅Output direct-current control voltage in parallel, in same circuit, D ₁With Q ₂Be the pipe of same semiconductor material, be applicable to the detection control that change in signal strength is bigger.

Description

Diode-triode mixture detector

The present invention relates to adopt in the electricity semiconductor devices to the demodulation of amplitude-modulated oscillation.

In radio communication and instrument measurement, carry out the detection demodulation for the amplitude modulation CF signal, employing diode mode, often to add bias voltage and temperature-compensation circuit, its low frequency signal and DC level output are all lower; Employing triode mode, except temperature-compensation circuit, also to add dc amplification circuit, to finish the automatic control to the prime signal level.The disclosed saturated detector of Chinese patent CN86108783A, take the triode static curve little saturated section, quiescent current is selected to require relatively stricter, too highly will make the curve variation, cross the low CB section that easily enters curve, cause distorted signals, therefore, because components and parts error in value, discreteness and temperature drift will bring very big difficulty to producing in batches to adjust.In addition, saturated detector is owing to be operated in little saturation state, so its input impedance is also lower, requires the prime intermediate frequency amplifier that higher gain is arranged, even will increase amplifying circuit, causes circuit complexity, cost to increase.

Purpose of the present invention provides a kind of diode-triode mixture detector that adapts to batch process, high impedance input, possesses higher direct current amplification output.

Fig. 1 is circuit principle structure figure of the present invention.

Q ₁The final stage radio frequency amplifier of general receiving equipment, R ₁R ₂Q ₁Direct current biasing resistance, C ₁Q ₁The input coupling capacitance, R ₃C ₃Q ₁The self-supporting bias compensation circuit of emitter stage.The invention is characterized in: at final stage radio frequency amplifier NPN pipe Q ₁Colelctor electrode and connect two loops to power supply V ₊, silicon (or germanium) the semiconductor diode D of NP connection is passed through in a loop ₁, be connected to radio frequency L ₁C ₂The inductance of the parallel resonance tank circuit, and pass through L ₁C ₂The parallel resonance tank circuit is communicated with dc power anode V ₊; Another loop is by silicon (or germanium) PNP transistor Q ₂Emitter junction NP, connect R ₄C ₄Parallel circuit is connected dc power anode V ₊, in same circuit, D ₁With Q ₂Pipe for same semiconductor material.

Can see Q from Fig. 1 ₁The colelctor electrode DC current of the pipe diode D that flows through ₁The pressure drop that produces is just in time with Q ₂The pipe base stage is basic identical to the initial conducting voltage of emitter stage, makes Q ₂Be in the state of slight conducting, therefore, Q ₂Emitter junction have very strong detectability for CF signal.Again because Q ₂Be the lightly conducting state, its base stage input current is very little, so Q ₂Pipe has the high impedance input, promotes power thereby reduced desired carrier frequency, and makes Q ₂Emitter stage R ₄C ₄Obtain the low frequency rectified signal output of higher level, the detection sensitivity height.Again because D ₁And Q ₂Pipe adopts same semiconductor material, and their temperature drift is consistent, and Q ₂The emitter junction direct-current working volts take from D ₁The direct current pressure drop, have each other good temperature compensation function, therefore, do not need cumbersome adjustment just can work, for batch production provides easily condition, Q ₂Colelctor electrode R ₅C ₅Output has the function that DC voltage amplifies, and can reach decades of times with respect to base stage input voltage amplification quantity, and DC voltage passes through R ₅C ₅Output is in order to the gain of automatic control prime.Only control first high level discharge in the practicality, its dynamic range can reach more than the 80dB.

In the practicality, Q ₁Be NPN type silicone tube 9016, Q ₂Be positive-negative-positive silicone tube 733, D ₁Be silicon diode 1N4148.

Work as Q ₁Adopt the positive-negative-positive transistor period of the day from 11 p.m. to 1 a.m, Q ₂Then adopt NPN N-type semiconductor N material pipe, D ₁And Q ₁Need to adopt the pipe of same semiconductor material, Q at this moment ₁Collector electrode also connects two loops to power cathode V _-, the formation of its circuit as shown in Figure 2, Q ₁With Q ₂The transistor of always different conduction forms.

The present invention has that circuit is simple, working stability, input impedance height, direct voltage output are big, control range broad, the higher characteristics of detection sensitivity automatically, is applicable to the detection control that change in signal strength is bigger.

Fig. 3 is the circuit block diagram that the present invention uses in pocket intercom.

Fig. 4 is the electrical schematic diagram that the present invention uses in pocket intercom.

The radiofrequency signal that is received by antenna is through Q ₃Height is put, Q ₄Mixing, Q ₁In broadcast to Q ₂Detection is by Q ₂The low frequency signal that emitter is exported after the detection is delivered to Q ₆Low putting is by Q ₂The collector electrode output dc voltage through R ₁₄, C ₁₅, D ₂, R ₁₈, R ₁₁Deliver to Q ₃Base stage is in order to control Q ₃The bias voltage of base stage.Because of Q ₃Be the forward agc circuit, change Q ₃The bias current of base stage can change Q ₃Amplification quantity.When the radiofrequency signal that receives when antenna increases, Q ₂The DC level of collector electrode output also increases, and this will cause Q ₃The bias current of base stage increases, and impels Q ₃Amplification quantity reduce, be unlikely when making the large-signal input and block or amplitude limit, thereby reach the purpose of AGC control.

Claims (4)

1, a kind of diode-triode mixture detector is made up of diode, triode, the radio frequency resonant tank circuit, resistance capacitance, it is characterized in that: at final stage radio frequency amplifier NPN pipe Q ₁Colelctor electrode and connect two loops to power supply V ₊, silicon (or germanium) the semiconductor diode D of NP connection is passed through in a loop ₁, be connected to radio frequency L ₁C ₂The inductance of the parallel resonance tank circuit, and pass through L ₁C ₂The parallel resonance tank circuit is communicated with dc power anode V ₊Another loop is by silicon (or germanium) PNP transistor Q ₂Emitter junction NP, connect R ₄C ₄Parallel circuit is connected dc power anode V ₊In same circuit, D ₁With Q ₂Pipe for same semiconductor material.

2, diode-triode mixture detector according to claim 1 is characterized in that: Q ₂Emitter stage passes through R ₄C ₄Output low frequency rectified signal in parallel, Q ₂Colelctor electrode passes through R ₅C ₅Output direct-current control voltage in parallel.

3, diode-triode mixture detector according to claim 1 is characterized in that: work as Q ₁When adopting positive-negative-positive semi-conducting material pipe, Q ₂Then adopt NPN type semi-conducting material pipe, D ₁With Q ₂Be the pipe of same semiconductor material, Q at this moment ₁Colelctor electrode also connects two loops to power cathode V _-

4, diode-triode mixture detector according to claim 1 is characterized in that: Q ₂The transistor detection is to be in slight conducting state.

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