CN105067126A - Infrared focal plane analog front-end circuit - Google Patents

Abstract

The invention provides an infrared focal plane analog front-end circuit. The circuit includes a control module circuit. The control module circuit includes a current mirror and a bias unit. The bias unit is used for controlling the initial current of the infrared focal plane analog front-end circuit. The initial current of the infrared focal plane analog front-end circuit will no longer be decided by resistance influenced by ambient temperature, and installation of a semiconductor cooler is not necessary.

Description

Infrared focus plane analog front circuit

Technical field

The invention belongs to infrared detection technique field, particularly a kind of infrared focus plane analog front circuit

Background technology

Infrared focus plane is the infrared detection technique of current main-stream, specifically mainly can be divided into two types: refrigeration mode and non-refrigeration type.The former is based on photoelectric effect, and how many charge carriers excited by detecting electromagnetic radiation realizes temperature survey; Latter is certain the fundamental characteristics directly electromagnetic radiation of absorption being converted to material, as the change of resistance, can realize temperature survey by the change of measured resistance value.The latter mainly designs based on vanadium oxide bollard bolometer, directly the electromagnetic radiation of absorption is converted to certain fundamental characteristics of material, as the change of resistance, can realize temperature survey by the change of measured resistance value.The resistance of Vanadium Oxide Thin Film Resistance can vary with temperature and change, near a certain temperature, can be approximated to be linear relationship: R (T)=R ₀(T ₀) (1+TCR ' DT). wherein TCR (TemperatureCoefficientofResistance) refers to temperature-coefficient of electrical resistance, and for Vanadium Oxide Thin Film Resistance, at room temperature, the value of TCR is-2% ~-3%.Under normal circumstances, we use semiconductor cooler to provide a relatively constant environment temperature environment temperature, but the introducing of semiconductor cooler adds extra power consumption and cost.

Summary of the invention

The object of the invention is to overcome the deficiencies in the prior art, a kind of infrared focus plane analog front circuit is provided.

The invention provides a kind of infrared focus plane analog front circuit, comprise the Infrared Detection Array of electrical connection, benchmark pixel and integrator, wherein, described Infrared Detection Array comprises photosensitive pixel resistance, described benchmark pixel comprises blind pixel resistance, also comprise control module circuit, described control module circuit comprises current mirror and bias unit, and described bias unit is for controlling the initial current size of described infrared focus plane analog front circuit.

In a preferred embodiment of the present invention, described bias unit comprises bias unit resistance, and described bias unit resistance is identical with the resistance of described blind pixel resistance.

In a preferred embodiment of the present invention, described current mirror application produces the electric current identical with photosensitive pixel resistor current with flowing through blind pixel resistance.

In a preferred embodiment of the present invention, described current mirror comprises the first current mirroring circuit and the second current mirroring circuit, described first current mirroring circuit is for generation of the electric current identical with flowing through blind pixel resistance, and described second current mirroring circuit is for generation of the electric current identical with flowing through photosensitive pixel resistance.

In a preferred embodiment of the present invention, described integrator comprises the adjustable integrating capacitor of numeral, and described integrating capacitor is identical with the setting range ratio of initial current.

In a preferred embodiment of the present invention, described bias unit resistance is Vanadium Oxide Thin Film Resistance.

Compared to prior art, infrared focus plane analog front circuit provided by the invention has following beneficial effect:

One, initial current is no longer determined by resistance influenced by ambient temperature, eliminates installation semiconductor cooler.

Two, the resistance of blind pixel resistance and photosensitive pixel electrical resistance temperature variation can not be reacted in final quantized result, therefore, as long as initial current is constant, and just can the change of equal interval quantizing temperature.

Accompanying drawing explanation

In order to be illustrated more clearly in the technical scheme in the embodiment of the present invention, below the accompanying drawing used required in describing embodiment is briefly described, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings, wherein:

Fig. 1 is the structured flowchart of infrared focus plane analog front circuit of the present invention;

Fig. 2 is the circuit diagram of the analog front circuit of infrared focus plane shown in Fig. 1.

Embodiment

Be clearly and completely described to the technical scheme in the embodiment of the present invention below, obviously, described embodiment is only a part of embodiment of the present invention, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making other embodiments all obtained under creative work prerequisite, belong to the scope of protection of the invention.

The invention discloses a kind of infrared focus plane analog front circuit, please refer to Fig. 1 and Fig. 2, described infrared focus plane analog front circuit 1 comprises the Infrared Detection Array 11 of electrical connection, benchmark pixel 12, integrator 13 and control module circuit 14, wherein, described Infrared Detection Array 11 comprises photosensitive pixel resistance 111, and described benchmark pixel 12 comprises blind pixel resistance 121.

Described control module circuit 14 comprises current mirror 141 and bias unit 142, and described bias unit 142 is for controlling the initial current I of described infrared focus plane analog front circuit 1 ₀size.

Described bias unit 142 comprises bias unit resistance 143, and described bias unit resistance 143 is identical with the resistance of described blind pixel resistance 121.

Described current mirror 141 is applied and is produced the electric current identical with photosensitive pixel resistance 111 electric current with flowing through blind pixel resistance 121.

Concrete, described current mirror 141 comprises the first current mirroring circuit 1411 and the second current mirroring circuit 1412, described first current mirroring circuit 1411 is for generation of the electric current identical with flowing through blind pixel resistance 121, and described second current mirroring circuit 1412 is for generation of the electric current identical with flowing through photosensitive pixel resistance 111.

In the present embodiment, described current mirror 141 copies to produce and identical flows through blind pixel resistance 121 (R _rEF) and photosensitive pixel resistance 111 (R _aCT) electric current, under the prerequisite of resistors match, the two has identical voltage drop, carries out the temperature sensing based on the detection of a target with this.

Further, setting initial current is I ₀, the resistance in described bias unit 142 is also vanadium oxide resistance, and all mates with blind pixel resistance 121, resistance is (R _rEF).Then in this case, integration current I _intexpression formula be:

$\begin{array}{c}{I}_{\mathrm{int}}=\frac{I_0\·R_{REF}}{R_{RCT}}-\frac{I_0\·R_{REF}}{R_{REF}}=I_0\·(\frac{R_{REF}}{R_{REF}\left(1+TCR\·\mathrm{\Δ}T\right)}-1)\\ \≈I_0\·\left(1-TCR\·\mathrm{\Δ}T-1\right)=I_0\left(-TCR\right)\·\mathrm{\Δ}T\end{array}$

By the available final voltage expression of described integrator 13 be:

$V_{out}=V_{cm}+T_{\mathrm{int}}\·\frac{I_0\·(-TCR)\·\mathrm{\Δ}T}{C_{\mathrm{int}}}$

When variation of ambient temperature is larger, basic resistance value R ₀(T ₀) may vary widely, this likely can make metal-oxide-semiconductor exit saturation region, cannot realize current replication.

Setting R ₀(T ₀) variation range be 1/5R ₀(T ₀) ~ 5R ₀(T ₀), therefore, by initial current I ₀be set as that numeral is adjustable: 5I ₀~ 1/5I ₀, guarantee that significant change can not occur in the voltage drop of blind pixel and photosensitive pixel, thus avoid some metal-oxide-semiconductor to enter the possibility of linear zone.

In order to ensure final integral result not by initial current I ₀the impact of change, described integrator 13 comprises the adjustable integrating capacitor 131 of numeral, that is, integrating capacitor 131 is set as that numeral is adjustable: 5Cint ~ 1/5Cint.

Described integrating capacitor 131 is identical, concrete with the setting range ratio of initial current, works as R ₀(T ₀) be changed to 1/5R ₀(T ₀) time, by initial current I ₀be set as 5I ₀, integrating capacitor 131 is set as 5Cint.

Work as R ₀(T ₀) be changed to 5R ₀(T ₀) time, by initial current I ₀be set as 1/5I ₀, integrating capacitor 131 is set as 1/5Cint.

Can be understood as, described initial current I ₀be not limited to above-mentioned setting value with the setting range of integrating capacitor 131, in the scope of setting, adjust described initial current I ₀with integrating capacitor 131 with the increase of identical multiple or be reduced to any numerical value, all in the scope that the present embodiment is claimed.

Compared to prior art, infrared focus plane analog front circuit provided by the invention has following beneficial effect:

One, initial current is no longer determined by resistance influenced by ambient temperature, eliminates installation semiconductor cooler.

Two, the resistance of blind pixel resistance and photosensitive pixel electrical resistance temperature variation can not be reacted in final quantized result, therefore, as long as initial current is constant, and just can the change of equal interval quantizing temperature.

The foregoing is only embodiments of the invention; not thereby the scope of the claims of the present invention is limited; every utilize description of the present invention to do equivalent structure or equivalent flow process conversion; or be directly or indirectly used in other relevant technical field, be all in like manner included in scope of patent protection of the present invention.

Claims (6)

1. an infrared focus plane analog front circuit, comprise the Infrared Detection Array of electrical connection, benchmark pixel and integrator, wherein, described Infrared Detection Array comprises photosensitive pixel resistance, described benchmark pixel comprises blind pixel resistance, it is characterized in that, also comprises control module circuit, described control module circuit comprises current mirror and bias unit, and described bias unit is for controlling the initial current size of described infrared focus plane analog front circuit.

2. infrared focus plane analog front circuit according to claim 1, is characterized in that, described bias unit comprises bias unit resistance, and described bias unit resistance is identical with the resistance of described blind pixel resistance.

3. infrared focus plane analog front circuit according to claim 1, is characterized in that, described current mirror application produces the electric current identical with photosensitive pixel resistor current with flowing through blind pixel resistance.

4. infrared focus plane analog front circuit according to claim 3, it is characterized in that, described current mirror comprises the first current mirroring circuit and the second current mirroring circuit, described first current mirroring circuit is for generation of the electric current identical with flowing through blind pixel resistance, and described second current mirroring circuit is for generation of the electric current identical with flowing through photosensitive pixel resistance.

5. infrared focus plane analog front circuit according to claim 1, is characterized in that, described integrator comprises the adjustable integrating capacitor of numeral, and described integrating capacitor is identical with the setting range ratio of initial current.

6. infrared focus plane analog front circuit according to claim 2, is characterized in that, described bias unit resistance is Vanadium Oxide Thin Film Resistance.